engineering field manual

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DRI LL IN G FLUIDS

TEST

PROCEDURES


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TABLE OF CONTENTS

1. WATERBASED FLUIDS1.1 ALKALINITY..................................................................................................6

1.2 AMMONIUM SULFATE ..............................................................................11

1.3 M.B.T. ................................................................................................................12

1.4 CHLORIDES ....................................................................................................14

1.5 LIQUID AND SOLIDS CONTENT (RETORT).......................................15

1.6 FILTRATION TESTS.....................................................................................18

1.7 FUNNEL VISCOSITY...................................................................................22

1.8 HYDROGEN ION DETERMINATION (pH)............................................23

1.9 HYDROGEN SULFIDE CONCENTRATION..........................................24

1.10 H2SCAVENGING ABILITY AND ZINC CARBONATE....................27

1.11 MUD DENSITY............................................................................................31

1.12 NITRATE ION CONCENTRATION ........................................................32

1.13 POLYACRYLAMIDE CONCENTRATION...........................................33

1 14 POTASSIUM ION ANALYSIS 34


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3. COMPLETION FLUIDS3.1 DENSITY..........................................................................................................66

3.2 TURBIDITY.....................................................................................................67

3.3 CRYSTALLIZATION TEMPERATURE...................................................68

3.4 CHEMICAL ANALYSIS...............................................................................69

4. DETERMINATION OF AVA PRODUCTS4.1 AVAGLYCO, AVAGLYCO MP .................................................................73

4.2 AVAPOLYSIL, AVASILIX, AVASHALESTOP/ACT,

AVAEASYDRILL .........................................................................................75

4.3 AVACLAYBLOCK, AVAFASTDRILL, AVASHALESTOP,

AVAPOLYMER 5050...................................................................................76

4.4 AVADES 100 ...................................................................................................77

4.5 AVAPOLYOIL (DEEPDRILL)................................................................79

4.6 AVABIOLUBE................................................................................................80

4.7 DEOXY DEHA ................................................................................................81


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Issue 1: May 2004 WBM AnalysisRev. 0 Page 5

-1-

WATER BASED FLUIDS


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1.1 ALKALINITY

Acidity is one measure of alkalinity that is indicated by pH. However, the nature and amount of

other ions such as carbonate or bicarbonate can also affect mud filtrates alkalinity. For fresh watermud systems these ions can be indicative of the rheological stability of such mud systems.Concentrations of either ion can result in high, low shear rate viscosity (yield point) and high,

progressive gel strengths. Three methods can be employed for the determination of carbonate andbicarbonate concentration. The very common Pf/Mf method is restricted to mud systems having a

low organic content whereas the P1/P2 method or the Garrett Gas Train may be used for better, morequantitative analysis, especially in the systems with high organic content.

A. Pf/MfMethod:

Equipment:1. Phenolphthalein indicator2. Bromocresol green indicator

(or methyl orange or methyl red indicators)3. Distilled water4. Sulfuric acid N/50 (0.02N)5. Beaker, 100 ml6. Stirrer + Stirring rod

7. Graduated pipette (1 ml)


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2Pf > Mf 0 1200(Mf Pf) 340(2Pf Mf)

2Pf < Mf 1220(Mf 2Pf) 1200Pf 0

B. P1/P2 Method:

Inorganic ions such as borate, silicate, sulfide, and phosphate ions can have a real effect on drillingmud alkalinity. Additionally, organic compounds (e.g., anionic organic thinners, fluid loss additives,or other polymers) and their degradation by-products may also affect the determination of the

relative amounts of carbonate, bicarbonate, or hydroxyl ions in solution. The P1/P2 methodeliminates these effects.

Equipment:1. Sodium hydroxide 0.2N2. Barium chloride 10%3. Phenolphthalein indicator4. Sulfuric acid N/50 (0.02N)

5. Beaker, 100 ml6. Stirrer + Stirring rod7. Distilled water

8. Graduated pipette (1 ml)

Test Procedure:

1 D t i th P f d i t tli d i t 1 3 f th P f/Mf th d If th P f 0 0 th


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WARNING: The reagents may be hazardous to the health and safety of the user i f

inappropria tely handled.


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C. Garrett Gas Train Method:

Either of the methods above is still subject to some error and certain situations may require yetanother method. The Garrett Gas Train separates gas from liquid, thereby preventing contaminationof the CO2 detecting Drger tube by the liquid phase. The CO2 Drger tube responds to the CO2

passing through it by progressively staining (purple) along its length as the hydrazine chemical and

the CO2 react causing a methyl violet indicator to turn purple. The stain length is dependent on theamount of CO2 present and the total gas volume that passed through the tube. Consequently, for

accurate results, the gas exiting the train must first be captured in a one litre gas bag to allow the CO2to mix uniformly with the carrier gas. Then the contents of the bag are drawn through the tube using10 strokes of the Drger hand pump. This will draw exactly 1 litre of gas through the tube.

Test Procedures:

1. Be sure the gas train is clean, dry and on a level surface.

2. With the regulator T-handle backed off, install and puncture a N2O gas cartridge.3. Add 20 ml distilled water to chamber No. 1. (The chambers are numbered beginning at the

regulator).4. Add 5 drops of octanol defoamer to chamber No. 1.5. Install the top on the gas train and evenly hand-tighten to seal all O-rings.6. Attach the flexible tubing from the regulator onto the dispersion tube of chamber No. 1.

7. Inject with syringe, an accurately measured sample of filtrate into chamber No. 1. See tablebelow.


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Calculations:

Carbonates (mg/L CO3-2) =

SV

LF

Carbonates (mg/L) L = tube stain length VS = ml of sampleF = tube factor

Care and Cleaning:

To clean the gas train, remove the flexible tubing and gas train top. Wash out the chambers using a

brush with warm water and mild detergent. Use a pipe cleaner to clean the passages between thechambers. Wash, rinse and then blow out the dispersion tube with air or nitrogen gas. Rinse the unitwith distilled water and allow draining dry.


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1.2 AMMONIUM SULFATE

Test is base on a colorimetric reaction.

Equipment:1. HACH AMMONIA NITROGEN TEST KIT (No. 1 8)2. Graduated cylinder, 100 ml3. Graduated pipette (1 ml)4. Graduated cylinder (10 ml)

Sample Preparation:

Add 0.25 ml filtrate to the 100 ml graduated cylinder. Dilute with distilled water to the 100 ml mark.

Cover with palm of hand and invert cylinder several times. From this 100 ml solution, pipet 1.0 mlto the 10 ml graduated cylinder. Dilute to the 10 ml mark with distilled water. Invert the cylinder

several times.

Fill one tube to white line with this solution. Fill other tube to white line with distilled water.

1. Add 3 drops of Nessler solution to each tube. Stir. Allow 10 minutes for colour development.

2. Insert the filtrate containing tube in the right opening in the top of the colour comparator.3. Insert the distilled water sample in the left opening in the top of the colour comparator.4. Hold the colour comparator up to a light such as the sky (preferable), a window or lamp and

i h h h i i h f h l di il l h i


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1.3 M.B.T. TEST

The methylene blue dye test, MBT, is used to determine the cation exchange capacity of the solids

present in a drilling mud. Only the reactive portions of the clays present are involved in the test andmaterials such as barite, carbonates and evaporites do not affect the results of the test since thesematerials do not adsorb methylene blue. The cation exchange capacity of some typical clay is:

Clay CEC (meq/100g)

Wyoming Bentonite 75Soft Shale 45

Kaolinite 10

Drilled Cuttings 8 12

For bentonite based mud systems the MBT provides an indication of the amount of reactive clays

which are present in the drilling mud solids and for bentonite free, water based mud systems theMBT reflects the reactivity of the drilled solids. The test cannot distinguish between the type of

clays but, if a reactivity for the drilled solids is known or assumed it can be used to determine theamount of bentonite present in bentonite based systems.

Equipment:1. Erlenmeyer flask

2. Hot plate3. Stirrer + Stirring rod

d id


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Calculations:

Methylene blue capacity (meq/100g) =M

T

W

V

Bentonite equivalent (ppb) =M

T

V

V5 Bentonite equivalent (kg/m3) =

M

T

V

V25.14

VT = ml of methylene blue solution

VM = ml of mud sample volume WM = weight of mud sample (g)

Care of reagents:

The methylene blue dye and hydrogen peroxide should be stored in a cool, dark place to extend theirlife. These solutions should be replaced every four months.

Figure 1: MBT test after several methylene blue additions.

A: 2 cm3

B: 4 cm3

C: 6 cm3

D: 7 cm3

3CD


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1.4 CHLORIDES

Chloride ions exist in a mud system as salts of sodium, magnesium, calcium or potassium. The

determination of the chloride ion present in the mud filtrate may give an indication of salt waterflows or the presence of a salt formation or stringer. In mud systems to which salt has been added,chloride ion measurements show the amount of salinity present in the mud.

Equipment:1. Silver nitrate solution:

- 0.1N (or 0.0282N) for low chloride concentrations

- 1N (or 0.282N) for high chloride concentrations2. Potassium chromate indicator (5% solution)3. Sulfuric acid (N/50)4. Phenolphthalein indicator

5. Graduated pipettes (1 ml)6. Titration beaker (100 ml)

7. Stirrer + Stirring rod

Test Procedure:

1. Measure 1.0 ml of filtrate into a white titration beaker and dilute to convenient volume with

distilled water.2. Add a few drops of phenolphthalein. If a pink colour develops add N/50 sulfuric acid until the

pink colour completely disappears (it is not necessary to record the volume of N/50 sulfuric


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1.5LIQUID AND SOLIDS CONTENT (RETORT)

The retort apparatus is used to determine the amount and type of solids and liquids present in a

drilling mud sample. Mud is placed in the steel container and then heated until the liquid portion isvaporized. The vapour is passed through a condenser in which it is cooled and then collected in agraduated cylinder. The volume of the water and oil is measured as a fraction of the total mud

volume. For accurate results a true mud density should be used for calculations, an accurate air freesample must be used and a volume correction factor should be determined for oil content if it is

present in the mud.

The correction factor, Fo, can be determined from running the retort in the manner described belowand determining the oil correction factor as the fraction of oil recovered by running the oil blank.(For some crude oils Fo may be as low as 0.6, i.e. only 6 ml of an accurately measured 10 ml samplewere recovered).

Equipment:

1. Retort kit or Ministill (20 or 50 ml capacity)2. Graduated cylinder, % or 20 ml or 50 ml

3. Anti seize grease4. Spatula5. Steel wool

Test Procedure:


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To calculate suspended solids, the following formula can be used:

VSS = %S %W Cl

Cl

21.11680000

VSS = Volume percent of suspended solids Cl = chlorides (mg/L)

B. Average density, HGS and LGS

Calculations:

Average density of solids is calculated:

dA =

S

OWMW

%

)%(%100 +

dA = average solids density (g/cm3) MW = mud weight (g/cm

3)

%O = Volume % oil %W = Volume % water%S = Volume % retort solids

Percentage of HGS and LGS can be calculated as follows:


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Volume Fraction Salt (as NaCl) in the Water PhaseChlor ide Content (mg/L) Volume Fraction (Salt) SG5000 0.003 1.004

10000 0.006 1.010

20000 0.012 1.021

30000 0.018 1.032

40000 0.023 1.043

60000 0.034 1.065

80000 0.045 1.082100000 0.057 1.098

120000 0.070 1.129

140000 0.082 1.149

160000 0.095 1.170

180000 0.108 1.194

Handling and Instrument Care:

1. Use the spatula to scrape the dried mud from the mud chamber and lid to assure correctvolume.

2. Use the high temperature lubricant on the threads of the mud chamber and lid to makedismantling easier.

3. Remove and replace any mud caked steel wool.


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1.6 FILTRATION TESTS

The filtration and wall building characteristics of a drilling mud are important for providing a

relative measure of the amount of mud filtrate invasion into a porous and permeable formation andthe amount of filter cake that will be deposited on the wall of the well bore wherever filtrationoccurs. From a drilling view point these properties give an indication of the amount of water (or oil)

wetting that can take place in filtrate sensitive formations and the potential for tight hole ordifferential sticking problems. For productive, hydrocarbon bearing formations these properties givean indication of the amount of filtrate invasion and permeability damage that can be expected.

Filtration tests are conducted under two different conditions.

1. The standard API filtration test is conducted at surface (or room) temperature and 700 kPa (100psi) pressure for thirty minutes. For this test the fluid loss is the volume (ml) of filtrate

collected in this time period and the filt er cake thickness (mm or 1/32 inch) is the thickness ofthe cake that is deposited on the filter paper in this time period.

2. The API high temperature, high pressure test (HTHP test) is conducted for thirty minutes of

filtration at a temperature of 149C (300 F) and a differential of 3450 kPa (500 psi). For this

test the filtrate must be collected under a back pressure of 700 kPa (100 psi) in order to preventvaporization of the filtrate.

For all filtration tests the filter paper characteristics are Whatmann 50 or equivalent and the filtrationarea is 4560 mm

2.


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B. Half Area Filter Press

This type of instrument is typical of a "half area" cell for which the filtrate volume must be doubledwhen the fluid loss is reported. The instrument is self contained with a CO2 cartridge in a cylinderfor its pressure source that is adjusted using the T-handle of the built-in regulator at the top of theinstrument. The mud cell is a rubber boot that is placed inside a holding cup to separate the mud

from the pressure source. The lip of the boot serves as the sealing surface onto which the half areafilter paper is placed prior to securing the lid into place. The lid, in the form of a screw cap or other

locking device, is either knurled on the inside to simulate a screen or it may contain an actual, fixedscreen. The relief valve (sliding bar) on the side of the cell must be open to apply pressure to the

outside of the boot and closed when the filtration test is complete in order to permit pressure to berelieved.

C. Model MB Filter Press

This instrument consists of a mud cell assembly, pressure regulator and gauge mounted on the top of

the carrying case. The cell is attached to the regulator by means of a coupling adapter by simplyinserting the male cell coupling into the female filter press coupling and turning clockwise turn.The cell is closed at the bottom by a lid fitted with a screen, by placing the lid firmly against thefilter paper and turning to the right until hand tight. This forces the filter paper against the O-ringfitted in the O-ring groove at the base of the cell. Pressure is supplied by a CO2 cartridge and may be

released by a bleed-off valve prior to uncoupling the cell. (The bleed-off valve is closed when thevalve is screwed in).


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B. High Temperature, High Pressure Filtration Test Instruments

A. Baroid, OFI Instruments

These instruments are O-ringed valve stems that act as valves which are closed when the stem istightened into the mud cell and opened by unscrewing the valve stem approximately one-half turn.

The pressure regulator and back pressure cylinder is attached to the valve stems with locking pins.The cell of this type of instrument is loaded by unscrewing the set screws in the cell body until the

cap can be removed. With the valve stem in the body and closed (tightened) mud is added to the cellto within 10 15 mm from the top. Filter paper is placed on top of the O-ring, which has its owngroove in the cell body. The cap is placed in the cell making sure that the set screw seats in the capmatch the screws in the cell. The pressure source is a CO2 cartridge located in the barrel of theregulator assembly. The back pressure attachment is required only for tests conducted at

temperatures above 95 C. The mud cell is placed into the heating well and seated on the alignmentpin located in the well. The filtrate volume obtained from this instrument must be doubled in order tocorrect the volume to the full sized paper.

B. FANN, OFI Instruments

These instruments use threaded valve stems with valves to which the pressure regulator assemblyand back pressure assembly are secured using a lock ring and slip coupling assembly. The cell is

filled by closing the valve on the cell, inverting it and then adding the drilling mud to within 10 15mm from the top. Filter paper is placed on the O-ring in its groove. The cap of the cell is secured


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temperature 2 C. If desired record surge volume after 2 seconds. If back pressure risesabove 100 psi during the test, cautiously bleed off pressure by collecting portion of the filtrate.Record the total volume.

7. The filtrate volume should be corrected to a filter area of 4581 mm2. (If the filter area is 2258

mm2, double filtrate volume and report.)

8. At the end of test, close both valves. Back T-handle screw off the regulator and bleed offpressure from both regulators.

9. CAUTION: Filtration cell will still contain about 500 psi. Maintain cell in upright position andcool to room temperature. (After the cell is cool, continue to hold cell upright (cap down) and

loosen the top valve to bleed off pressure slowly).10. After the cell has cooled and the pressure has been bled off, the cell may be inverted to loosen

the cap screws with an Allen wrench, remove the cap with a gentle rocking motion, carefullyretain the filter cake for analysis and thoroughly clean and dry all components.

11. Do not use filtrate for chemical analysis.12. If filter cake compressibility is desired the test can be repeated using 200 psi on the top-

pressure and 100 psi for bottom pressure.13. Record both temperature and pressure with the results of the filtration test at all times. The

temperature of 149 C was selected so as to be within the range where high temperature mudtreating procedures and chemicals are required.

Calculation:

HPHT filtrate (ml) = 2VF


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1.7 FUNNEL VISCOSITY

Funnel viscosity is an indication of the overall viscosity of a drilling mud. It is affected by the

concentrat ion, type, size and size distribution of the solids present and the electrochemical nature ofthe drilling mud's solid and liquid phase. Consequently funnel viscosity should only be used to

provide an indication of change or consistency of viscosity from t ime to time. Since gel strength can

have a great effect on the magnitude of the funnel viscosity, the measurement should be taken asquickly as possibly.

Funnel Calibration:

With the funnel in an upright position, fill it with freshwater (at 20 C) to the level of the screen witha finger placed over the orifice. With the aid of the measuring cup (viscosity cup) the time taken forone quart of water to pass through the funnel orifice tube should be 26 seconds.

NOTE: The marsh funnel or if ice is a tube, 50.8 mm in length and 4.76 mm in in ternal

diameter. The orif ice may be cleaned by passing a 4.76 mm (3/l6 inch) dr il l through i tby hand.

Test Procedure:

1. With the funnel in an upright position, cover the orifice with a finger and rapidly pour a freshlycollected mud sample through the screen and into the funnel until the mud just touches the baseof the screen, (1500 ml). See note below.


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1.8 HYDROGEN ION DETERMINATION (pH)

The acidity or alkalinity of a drilling mud is indicated by the hydrogen ion concentration, which is

commonly expressed in terms of pH. A perfectly neutral solution has a pH of 7.0 whereas alkaline(basic) solutions have a pH range between 7.0-14.0 and acidic solutions have a pH less than 7.0.

The pH measurement is used as well to indicate the presence of contaminants such as cement oranhydrite.

The two most common field methods for determining pH are described below:

A. Method 1: pH-paper:

1. This method may be used on the mud filtrate or the mud directly.

2. Place a 25 mm strip of indicator paper on the surface of the mud to be tested and allow it toremain until the liquid has wet the surface and the colour has stabilized, (approximately one

minute).3. Compare the colour standards provided with the test paper (which was not in contact with the

mud solids) to the colour standards provided with the test paper and estimate the pH of the mudaccordingly.

B. Method 2: colour pH strip:


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1.9 HYDROGEN SULFIDE CONCENTRATION

In many areas hydrogen sulfide (H2S) is found by itself or in association with hydrocarbons,

especially gas. Hydrogen sulfide gas is not only very lethal but also extremely corrosive. Therefore,when H2S is encountered in the mud it must be reduced t o acceptable levels so that it does not pose ahealth hazard or create drill string failure.

The concentration of hydrogen sulfide present may be determined using the Hach Model HS-7Hydrogen sulfide kit or more quantitatively using the Garrett Gas Train.

A. Method 1: Hach Kit

Equipment:1. Hach Model HS-7 Hydrogen sulfide kit2. Graduated flask 25 ml

3. Graduated pipette 5 ml or 10 ml

Test Procedure:

1. Fill the sample vial to the 25 ml mark with recently filter pressed filtrate from the mud to be

tested. (If 25 ml are not available use a known amount of filtrate and dilute to 25 ml usingdistilled water; 5 or more ml of filtrate are recommended).


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B. Method 2: Garrett Gas TrainEquipment:1. Garrett Gas with H2S Drger tubes & floating ball flow meter2. Hydrogen sulfide (Hach), paper disks as alternative to Drger tubes

(for more qualitative test)

3. Sulfuric acid (5N)4. Dropper bottle with octanol defoamer or equivalent

5. Hypodermic syringe (10 ml with 21 gauge needle)6. CO2 cartridges

Test Procedure:

1. Be sure the gas train is clean, dry and on a level surface.

NOTE: Moisture in the flow metre can cause the ball to fl oat err aticall y.

2. With the regulator T- handle backed off, install and puncture a CO2 gas cartridge.3. Add 20 ml distilled water to chamber No. 1. (The chambers are numbered beginning at the

regulator).4. Add 5 drops of octanol defoamer to chamber No. 1.

5. Measure the sample into chamber No. 1. according to the following table:


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14. Observe a colour change on the Drger tube if H2S is present. In the units marked on the tube,

note and record the maximum darkened length before the front starts to smear. Continue flowfor 15 minutes although the front may attain a diffuse, feathery colouration. On the high rangetube an orange colour may appear ahead of the black front if sulfites are present. The orangeregion should be ignored when recording the darkened length.

Calculations:

VLFS =2

S-2

= mg/L sulfides F = tube factorL = tube stain length V = ml of sample volume

Care and Cleaning:

To clean the gas train, remove the flexible tubing and gas train top. Take the Drger tube and flowmetre out of the receptacles and plug the holes with stoppers to keep them dry. Wash out the

chambers using a brush with warm water and mild detergent. Use a pipe cleaner to clean thepassages between the chambers. Wash, rinse and then blow out the dispersion tube with air or CO2gas. Rinse the unit with distilled water and allow draining dry.

NOTE A lead acetate paper disc (Hach) fitted below the O-r ing of chamber No. 3can be substitu ted for the Drger tube in the gas train. The lead acetate


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1.10 HYDROGEN SULFIDE SCAVENGING ABILITY AND

ZINC CARBONATEWhen zinc carbonate is used as a drilling mud additive to scavenge hydrogen sulfide, H2S, in a sourgas well it is possible to obtain an estimate of the scavenging ability of the drilling mud as well asthe amount of zinc carbonate present. Quantitatively, the scavenging ability of the mud and therefore

the amount of zinc carbonate present can be determined using the Garrett Gas Train. A morequalitative method to determine the amount of zinc carbonate present employs the Hach Hydrogen

Sulfide test kit.

A. Estimation of Zinc Carbonate Concentration (Qualitative):

Equipment & Reagents:1. Hach Model HS-Y Hydrogen sulfide kit2. Filter press3. Hamilton Beach mixer or equivalent4. Hypodermic syringe, 5 ml

5. Fresh sodium sulfide, (Na2S), stock solution 100 g/L Na2S6. 5N Sulfuric acid7. Distilled water8. Defoamer, octanol or equivalent

Test Procedure:


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B. H2S Scavenging Ability and Zinc Carbonate Concentration:

Equipment & Reagents:1. Garret Gas Train with H2S Drger tubes & floating ball flow metre & CO2 gas

cartridges2. Sulfuric acid (5N)

3. Dropper bottle with octanol defoamer or equivalent4. Hypodermic syringe with 21 gauge needle (10ml)

5. Two, minimum 400 ml jars with lids6. Osterizer blender, blade type, 10 speed7. Filter press8. Fresh sodium sulfide (Na2S) stock solution (100 g/l)

Test Procedure:

1. Label two jars. "A" and "B".2. Measure 350 ml of drilling mud into jar "A".

3. Measure 350 ml of distilled water into jar "B".4. Measure 20 ml of stock sodium sulfide (Na2S) solution into each jar, close both jars and shake

vigorously by hand for thirty seconds. Transfer the contents of jar A to the Osterizer mixingjar, replace the lid, and stir at the slowest speed for 15 minutes. Transfer the drilling mud - H2S

system back to jar A.


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i. Adjust the dispersion tube of chamber No.1 to within 5 mm from the bottom.

j. Flow CO2 gas gently through train for 10 seconds to purge system of air. Stop gasflow.

7. Proceed to the Garrett Gas Train operating procedure outlined below:a. Using the hypodermic syringe, inject 4.0 ml of filtrate ("B") into chamber No.1.

b. Slowly inject 10 ml 5N sulfuric acid solution into chamber No. l through the septumusing the syringe and needle.

c. Immediately restart CO2 flow. Using the regulator, adjust the flow so that the ballremains between the two lines on the flow metre tube.

NOTE: One CO2cartr idge should provide 15-20 minutes of flow at this rate.

d. Observe a colour change on the Drger tube. In the units marked on the tube, noteand record the maximum darkened length before the front starts to smear. Continueflow for 15 minutes although the front may attain a diffuse, feathery colouration.

On the high range tube an orange colour may appear ahead of the black front ifsulfites are present. The orange region should be ignored when recording thedarkened length.

8. Label the darkened, stained length as "B".

9. Filter the mud (A) to obtain at least 4 ml of filtrate, label filtrate A.10. Clean the gas train as outlined below:


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WARNING: The reagents in the ki t may be hazardous to the health and safety of the user if

inappropriately handled. Please read all warnings before performing the test anduse appropriate safety equipment.

NOTE: The 100 g/L Na2S solution can deteriorate with time. I f the 4.0 cm3of fi ltrate B

resul ts in Drger tube dark lengths, which are too short, the fil trate volumes canbe increased. I f filtrate sample volume is indeed increased the equation used tocalculate H2S scavenging abili ty is changed from:

H2S scavenging abili ty (mg/L) = 375(B A)

to:

mg/L H2S scavenging abil i ty =V

AB )(1500

V = new volume (ml)


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1.11 MUD DENSITY

Drilling mud density is required to calculate the hydrostatic pressure that is being exerted by a

column of drilling mud at any given depth. Density is also used to provide an indication of the solidscontent of a drilling mud.

When the test is performed using a standard mud balance, care must be taken to ensure that the cupis full and free of entrapped air.

Mud Balance Calibration:

1. Remove the lid and completely fill the cup with distilled water at room temperature.2. Replace the lid carefully and wipe the entire balance dry.3. Place the balance arm on the base with the knife edge resting on the fulcrum.

4. With the rider placed at 1000 kg/m3

(s.g. = 1.0 or 8.33 lb/gal), the bubble of the level vialshould oscillate the same distance to the left and right of the centering mark above the vial. If

not, the calibration screw at the end of the balance should be adjusted until the oscillations areequal. (Some balances do not have an adjustment screw and require lead shot to be removed or

added through a calibration cap.)

NOTE: A more accurate reading is obtained if the mud balance is permitted tooscil late on its knif e edge rather than al lowing it to come to rest with thebubble centered over the centering mark.


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1.12 NITRATE ION CONCENTRATION

In some instances, after a potential producing horizon is drilled, it is desirable to know how much

drilling mud filtrate has permeated the zone. In order to differentiate drilling mud filtrate fromformation water a "tracer" is often introduced into the drilling mud. The nitrate ion is often used assuch a tracer.

Equipment:1. Hach Model NI-11 nitrate test kit, 0 50 mg/l

2. Distilled water

Test Procedure:

To obtain accurate test results please read carefully before proceeding:

Samples containing above 50 mg/L nitrate nitrogen can be tested by diluting the sample before

runnin g the test. For example, a one to five dilution can be made by using 1.0 ml of the water to betested and 4.0 ml of demineralised water. Use the calibrated dropper provided in this kit for the

dilution. Demineralised water is not included in this kit. The results of a one to five dilution aremultiplied by five to obtain the correct mg/L nitrate nitrogen. The results of other dilutions willfollow the same procedure as above; for example, the results of a one to three dilution would be

multiplied by three.

A small portion of the Nitraver nitrate reagent will remain un -dissolved and fall to the bottom of the


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1.13 POLYACRYLAMIDE CONCENTRATION

Very often, mud systems may utilize a partially hydrolyzed polyacrylamide, PHPA, to provide or

enhance inhibition by encapsulation of the polymer around the hydratable clays that are encounteredwhile drilling. In order for this method of inhibition to be effective, a residual PHPA concentrationmust be present in the drilling mud filtrate.

Equipment:1. Hand cranking centrifuge

2. 2 Graduated centrifuge tubes3. Floc developer solution4. Cresol red indicator5. Hydrochloric acid (0.2N)6. Sodium hydroxide (0.2N)

Test Procedure:

1. Measure 12 ml fresh water into a test tube and place in centrifuge tube for balance.

2. Measure 10.0 ml filtrate in the graduated centrifuge tube.3. Add 6 drops of cresol red indicator and with the tube covered invert gently. A reddish purple

colour will develop to indicate a pH greater than 7.0.

4. Add 0.2N hydrochloric acid, drop by drop, inverting gently each time until the solution justturns an orange-yellow.

5. Add 2ml floc developer solution.

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1.14 POTASSIUM ION ANALYSIS

When a drilling mud containing potassium ions (KCl or K2CO3) is used, the primary purpose is to

prevent, or at least minimize hydration of water sensitive formations. Inhibition of hydration isprovided by the potassium ion K

+, which is attracted to negative charges appearing through the flat

surface. Therefore, it is extremely important to know the potassium ion concentration at all times in

these mud systems. In KCl mud, by monitoring the potassium to chloride ion ratio (K+/Cl

-) while

drilling the more hydratable formations should coincide with points having a low ratio.

A. Method One:

Equipment:1. Hand cranking centrifuge2. 2 Graduated, 15 ml centrifuge tubes

3. 750 g/L sodium perchlorate precipitating solution

Test Procedure:

1. In order to balance the centrifuge, measure 14 ml of fresh water in the other centrifuge tubeand place it into the centrifuge.

2. Add 4.0 ml sodium perchlorate to 10.0 ml of filtrate to be tested in the centrifuge tube. A white

precipitate, which forms immediately, indicates the presence of potassium.3. Invert slowly for one minute and place in the centrifuge.4. Centrifuge for one minute at a cranking speed of 120 rpm (10 revolutions every 5 seconds).

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Potassium Ion ConcentrationFloc Volume (ml) Potassium I on Concentration (mg/L)

0.00 0

0.25 5000

0.50 7500

0.80 10000

1.10 15000

1.30 19000

1.50 245001.70 31000

1.90 38000

2.10 45000

2.30 53000

2.50 59000

2.70 65000

2.90 700003.10 75500

3.30 81000

NOTE: 5250 mg/L K+is approximately 10 kg/m3KCl (K+/KCl = 39/74.50.5)

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Calculations:

K+

(mg/L) =F

T

V

V )0.25(1000

VT = ml of QAS usedVF = ml of API filtrate used (see table)

Approx. K+ in mud (mg/L) VF to use (ml)250 2000 10.0

2000 4000 5.0

4000 10000 2.0

10000 20000 1.0

> 20000 0.5

NOTE: Potassium buffer solution (NaOH) is corrosive and causes severe burns. Avoid contactwith eyes and skin. Store in a plastic bottle.



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1.15 RHEOLOGICAL MEASUREMENTS

In the field, the rheological characteristics of a drilling mud are determined with a concentric

rotational viscometer having an industry standardized bob and sleeve. Shear stress, viscosity or gelstrength is determined from the degree of rotation of the bob under the influence of the shear ratecreated in the mud by the action of the outer, rotating sleeve. Because most drilling muds are non-

Newtonian in behaviour, (pseudo-plastic and thixotropic), stress, viscosity and gel strengthmeasurements must be performed at prescribed shear rates (rotational speeds). The industry standardrotational speeds are 600 and 300 rpm for any steady state rheological parameter and 3 rpm for gel

strength (an indication of thixotropy) measurements.

The most common field viscometers are:

A. OFI Rheometer Model 800:

This is an 8-speed viscometer capable also of stirring mud.The stirring speed is obtained by moving the shift lever counter clockwise as far as possible, the 600rpm speed is obtained by moving the shift lever counter clockwise from the stirring speed to the first

detent position. Is possible to make rheology measurements at 600, 300, 200, 100, 60, 30, 6 and 3rpm. Connect the instrument to the power supply and switch on the button at the back of theviscometer body.

B. FANN Model 35SA:



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A. PROCEDURE FOR RHEOLOGICAL MEASUREMENTS:

In conventional field practices the steady state rheological description of a drilling mud is given interms of the parameters, which describe the fluid as an ideal Bingham Plastic. These parameters arethe plastic viscosity and yield point (or yield stress). The time dependent nature of the drilling mud(thixotropy) is measured in terms of gel strength.

The temperature at which rheological measurements are taken should be const ant and always berecorded.

I. PLASTIC VISCOSITY AND YIELD POINT

Place a recently agitated sample in a suitable container and lower the instrument head until thesleeve is immersed in the drilling mud sample exactly at the scribed line of the sleeve. With the

instrument set at 600 rpm rotate the sleeve until a steady dial reading is obtained, (for highlythixotropic muds this may take some time). Consistency of results can be achieved if the 600 rpmdial reading is taken at the point for which the change in dial reading is less than one degree (one

dial division over a stirring time of one minute).

When the dial reading has reached this steady value, record this as the 600 rpm dial reading, 600.

Lower the speed to 300 rpm and stir the sample at this speed until a steady reading is obtained using

the same criterion for the steady state point. Record this value as the 300 rpm dial reading, 300.



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5. Repeat steps (l)-(2) and in step (3) allow a rest time of 10 minutes.6. Record the maximum dial deflection as the 10 minute gel strength dial reading.

Calculations:

Gel strength (lb/100ft2) = 3 for 0, 10 or 10

Gel strength (g/100cm2) =

2

3for 0, 10 or 10

3 = 3 rpm reading

NOTE: I f the in it ial and l0 minute gel strengths are equal, the mud has no thixotropy, i.e., themud has no abil ity to build structure whi le it is at rest. This type of mud does not haveany real gel strength or increased suspending power whi le it is at rest. For thi s type ofmud the gel break is not very evident, rather i t will be a gradual increase to a steady

value. Thi s is indicated by lower ten minute gel strength in comparison to higher ini tialgel strength.

III. INSTRUMENT CARE:

After every usage the instrument should be thoroughly cleaned.

1 Run the rotor immersed in water (or solvent for oil based muds) at high speed for a short



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1.16 SAND CONTENT

The API sand content is defined to be that portion of the drilling mud solids whose size is greater

than 74 microns (m). The test can be used to give a qualitative, relative indication of the solidsremoval equipment effectiveness, the relative amount of coarse barite present and the abrasivenessof the mud.

Equipment:1. Screen sand content

2. Funnel sand content3. Tube sand content

Test Procedure:

1. Fill the glass measuring tube to the indicated mark with mud to be tested. Add water to the nextmark. Close the mouth of the tube and shake vigorously.

2. Pour the mixture onto the screen tapping it lightly to aid passing of the diluted mud through thescreen. Add more clean water and repeat this wet screening procedure until the wash water in

the tube is clear. Wash the sand retained on the screen to free it of any remaining mud.3. With the sieve in an upright position, fit the funnel over the sieve, invert slowly and fit the

funnel tip into the mouth of the cleaned measuring tube. Back wash the sand from the sieve

using a fine spray of clean water with the measuring tube positioned vertically upright, allowthe sand to settle in the tube for a few minutes. Report the sand content as the volume fractionof sand, (the volume percent divided by 100). For example if the sand content is read as 0.4%



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1.17 SULFATE ION CONCENTRATION

Sulfate ions are present in many natural, ground and surface waters. In bentonite based mud systems

flocculation and resultant high viscosity can result from sulfate ion concentrations approaching orexceeding 2000 mg/l. A qualitative or more quantitative test can be performed to establish the sulfateconcentration.

A. Qualitative Test:

Equipment:1. Dropper bottle of barium chloride (10% solution)2. Dropper bottle of strong nitric acid3. Test tube

Test Procedure:

1. Place 2-4 ml of filtrate in a test tube and add a few drops of barium chloride.2. Shake the tube gently and observe the presence of a milky, white precipitate. This indicates thepresence of carbonates and/or sulfates.

3. Add a few drops of nitric acid and shake again. If the precipitate dissolves and disappearscompletely, only carbonates were present. If the precipitate remains, its intensity can be used

for a qualitative estimate of the sulfate concentration.

Results:



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B. Quantitative Test:

One method of quantitatively determining the sulfate ion concentration is with the use of the HachModel SF-1 Sulfate Kit.

Equipment:1. Hach Model SF-1 Sulfate Kit

Test Procedure:

1. Fill the calibration tube to the top with filtrate to be tested.2. Pour this sample into the mixing tube.3. Add the contents of one SulfaVer IV powder pillow. Swirl to mix. A white, turbid precipitate

will appear if sulfate is present.

4. Allow to stand for 5 minutes.5. Hold the calibrated tube in such a manner so that it can be viewed through the top. Slowly pour

the prepared sample into the tube. Contin ue pouring until the image of the black cross on the

bottom of the tube just disappears from view. At this point the tube will appear as a uniformfield of view.

6. Read mg/L sulfate (SO4-2) from the scale on the side of the calibrated tube.

NOTE: The dif ference between mg/L and ppm is not signi f icant unti l sul fateconcentrations exceed 7000 mg/L .



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1.18 SULFITE ION CONCENTRATION

In many mud systems, especially those, which contain high levels of salt, it is necessary to use an

oxygen scavenger to reduce the dissolved oxygen content in the drilling mud in order to reduce drillstring corrosion to acceptable levels. One method of reducing oxygen corrosion is with the use ofany oxygen seeking ion like the sulfite (SO 3

-2) ion, which will react with the dissolved oxygen

present in the drilling mud. In order to minimize oxygen corrosion it is necessary to maintain aresidual sulfite concentration in the drilling mud at all times. Usually, residual concentrations in theorder of 300 mg/L or greater are required to reduce corrosion to acceptable levels. Corrosion results

should always be verified with the use of corrosion rings.

One method of determining the residual sulfite concentration is with the use of the HACH ModelSU-5 Sulfite Kit. The sulfite concentration may be determined using mud or mud filtrate.

Equipment:1. Hach Model SU-5 Sulfite Kit

Test Procedure:

1. Measure a sample by filling the sample bottle to the indicated mark, 10 ml.2. Add the contents of one Sulfite 1 reagent powder pillow. Swirl to mix.

3. Add the contents of one sulfamic acid powder pillow. Swirl to mix.4. Titrate with sulfite 3 reagent using the eye dropper, (low and high range Sulfite 3 reagent is

available). Add the reagent drop wise with continual swirling of the sample until a permanent

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1.19 TOTAL & CALCIUM HARDNESS

Water containing large amounts of calcium or magnesium salts is commonly referred to as "hard

water". Make-up waters that are hard make it difficult to obtain the maximum yield from bentoniteso it becomes necessary to treat our excess calcium, (for this purpose the total hardness as calciumshould be brought to less than 40 mg/l). The presence of calcium in the mud filtrate may also

indicate the presence of contaminants such as anhydrite or cement.

Equipment :

1. Titraver 400 or EDTA (ethylene diammino tetracetic acid) 0.01M2. Ammonia buffer (hardness buffer)3. Eriochrome black T (total hardness indicator)4. Graduated pipettes (1 ml)5. Distilled water

6. Stirrer + Stirring rod7. Calver II indicator or murexide (to distinguish calcium from magnesium)8. Sodium hydroxide (0.1N) solution (to distinguish calcium from magnesium)

9. Methyl red or Potassium chromate 5% indicator (facultative)

A. Total Hardness (as calcium):

Test Procedure:

1. Using a pipette, measure 1.0 ml of filtrate into a white titration dish and dilute to a convenient

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B. Calcium hardness:

Test Procedure:

1. Using a pipette, measure 1.0 ml filtrate into a white titration dish and dilute with a smallamount of distilled water.

2. Add 2 drops of 0.1N NaOH (sodium hydroxide). Solution pH must be approx. 12 13.3. Add several grains of calver II (or murexide) and swirl or stir to mix.

4. Using a pipette, titrate with titraver (or EDTA) to a colour change from red to blue.

Calculation:

Calcium hardness (Ca+2

, mg/L) = 400V

V = ml of Titraver 400 (or EDTA 0.01M) added

NOTE: To better appreciate color change at end poin t, add 2 drops of methyl red (or potassiumchromate) indicator unti l soluti on becomes orange (red + yell ow): af ter titration colorwil l change to green (blue + yell ow).

C. Magnesium hardness:

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1.20 LIME CONTENT

Lime content in a drilling fluid can be determined with P f/Mfalkalinity method.

Test Procedure:

1. Determine P fand M fas described.2. Determine the % volume of water from retort analysis (%W)3. Calculate the lime content.

Calculations:

Lime content (ppb) = 0.26 (Pm FP f)

Lime content (kg/m3) = 0.742(Pm FP f)

F = %W/100

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1.21 TRU WATE MUD BALANCE

When a drilling mud contains entrapped air or it is experiencing a foaming problem the mud density

may be accurately determined with a pressurized mud balance.

Test Procedure:

1. Fill the sample cup with drilling mud to a level, which is approximately 10 mm below theupper edge of the cup.

2. Place the lid on the cup with the attached check valve in the down (open) position. Push the liddownward into the mouth of the cup until surface contact is made between the outer skirt of thelid and the upper edge of the cup allowing any excess mud to be expelled through the opencheck valve.

3. Pull the check valve up into the closed position, rinse off the cup and threads, and then, screw

the threaded cap onto the cup.4. With the plunger in hand, push its handle in to place the inner piston to its lower most position.

Fill the plunger by immersing its nose in the mud to be tested and pulling out the handle until

the inner piston is in its upper most position. (The plunger's operation is similar to a syringe orbicycle pump).

5. Place the nose of the plunger onto the mating O-ring surface of the valve on the cap. Thesample cup is pressurized by maintaining a downward force on the cylinder in order to hold the

check valve down (open) and at the same time forcing the piston inward. Approximately 220Newton of force are required on the plunger handle in order to pressurize the sample cup.

6. The check valve in the lid is pressure actuated and will close (move up) under the influence of

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OIL BASED FLUIDS

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2.1 WHOLE MUD ALKALINITY

Equipment:1. n-propoxypropanol solvent

(or isopropyl alcohol / hexyl alcohol = 50/50)2. Phenolphthalein indicator

3. 250 ml Erlenmeyer flask4. Magnetic stirrer5. Sulfuric acid N/10 (0.1N)

6. Graduated Pipettes (1 ml)7. Glass syringe (5 ml)

Procedure:

1. To 50 ml of n- propoxypropanol, add 1.0 ml of oil mud, and stir well on magnetic stirrer.2. Add 100 ml of distilled water and 5 drops of phenolphthalein indicator.3. While rapidly stirring, slowly titrate entire mixture with N/10 (0.1N) H2SO4 until the pink color

disappears.4. Wait for 5 minutes without stirring: if no pink colors appears, then record the ml of N/10

Sulfuric acid required as VSA.5. If solution turns pink, then titrate until the pink color disappears*.

6. Record total ml of N/10 Sulfuric acid required as VSA

NOTE: Adequate venti lation should be main tained using thi s procedure to avoid



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g

2.2 WHOLE MUD CALCIUM

Equipment:1. n- propoxypropanol solvent

(or isopropyl alcohol / hexyl alcohol = 50/50)2. Titraver 4000 (or EDTA 0.1M)

3. Calcium buffer (1N NaOH solution)4. Graduated pipette (1 ml)5. Calver II indicator or murexide

6. Magnetic stirrer + stirring rod7. Glass syringe (5 ml)8. 250 ml Erlenmeyer flask

Procedure:

1. To 50 ml of n- proproxypropanol, add 1.0 ml of oil mud. Mix well on magnetic stirrer for 2minutes to break the emulsion.

2. While stirring, add 100 ml of distilled water, 2 ml of calcium buffer and 0.1-0.2 grams ofCalver II indicator powder.

3. Slowly stir only to agitate the aqueous (lower) phase.4. Titrate very slowly until the color changes from a light purple to a deep blue.

NOTE: Adequate venti lation should be main tained using thi s procedure to avoidinhalation of the organic solvents.



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g

2.3 WHOLE MUD CHLORIDES

Equipment:1. Potassium chromate indicator (5% aqueous solution)2. Silver nitrate solution:

- 0.0282N (or 0.1N) for low chloride concentrations

- 0.282N (or 1.0) for high chloride concentrations3. Graduated pipettes (1 ml )4. Magnetic stirrer + stirring rod

Procedure:

This titration is performed after determining the P OM alkalinity on the titrated sample.1. Make sure that solution is acidic (add 5 10 drops of N/10 sulfuric acid).

2. Add 10 15 drops of Potassium Chromate indicator.3. While rapidly stirring, slowly titrate the mixture with Silver nitrate until the first permanent

red/orange color appears.

NOTE: Adequate venti lation should be maintained using this procedure to avoid inhalationof the organic solvents.

Calculations:

(a) ClOM = VT10000 (b) ClOM = VT1000



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2.4 DENSITY

Equipment:1. Mud balance

Procedure:

1. The method for obtaining the density of an invert mud is identical to that used for a water-based fluid. Insure that the invert mud's temperature is approximately room temperature (i.e.

20-25C) before weighing.

Conversion factors:

kg/m3

= Specific Gravity1000kg/m

3= pounds/gal (ppg) 119.826

kg/m3

= pounds/ft3

(pcf)16.051

SG (g/cm3) =345.843.62

ppgpcf =

Alternate Density measurements with Tru-Wate balance:

The density of mud containing entrained air or gas can be determined more accurately by using thepressurized fluid density balance (Tru-wate). The pressurized fluid density balance is similar in



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6. The pressurized slurry sample is now ready for weighing. Rinse the exterior of the cup and

wipe dry. Place instrument on the knife edge as illustrated. Move the sliding weight right orleft until the beam is balanced. The beam is balanced when the attached bubble is centered

between the two black marks. Read the density from one of the four calibrated scales on thearrow side of the sliding weight. The density can be read in units of lb/gal, specific gravity,

psi/1000ft, and lb/ft3.

7. To release the pressure inside the cup reconnect the empty plunger assembly and pushdownward on the cylinder housing.

8. Clean the cup and rinse thoroughly with base oil.



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2.5 EMULSION STABILITY

This is another indication of the emulsions integrity in an Invert emulsion. This test is run afterdetermining the rheology. The sample remains in the thermo-cup at 50C and the electrical stability

probe is inserted. The voltage required to break the emulsion is taken while making sure the probedoes not touch any part of the thermo-cup. This test should be taken 3 times with the results

averaged.

Equipment:

1. OFI model 131-50 orFANN model 23D

Test Procedure:

1. Place the fluid in a non-conductive container and heat to 49C (120F). (Same temperatureused in Rheology).

2. Insert probe into fluid ensuring that end is totally immersed.

3. Hand-stir the sample with the probe for 10 sec.4. Depress button on meter until steady reading is observed.5. Take three readings and average the results. Readings should be recorded in Volts.6. Clean probe immediately after use.

Discussion of results:



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2.6 HT/HP FILTRATION

All invert systems should be tested in the following manner for filtration loss since API 30 minute(100 psi) does not give accurate fluid loss values for invert drilling fluids at anticipated wellboretemperatures and pressures.

The HTHP fluid loss is normally operated at bottom hole temperatures with a 3500 kPa (500 psi)differential pressure. The fluid is collected over 30 minutes and multiplied by 2 before beingreported (half area filter paper is used).

At elevated temperatures (> 100C) it will be necessary to have a regulator on the bottom to provideback pressure. The bottom would have 700 kPa (100 psi) and the top would have 4200 kPa (600 psi)in order to maintain a 500 psi differential.

The absence of water in the filtrate collected indicates that the emulsion is tight.

Equipment:1. OFI Instruments HTHP Fluid loss apparatus2. HPHT filter paper3. Graduated cylinder (5 or 10 ml)

Test Procedure:

1. Connect the heating jacket to power supply (be sure that voltage is adequate) before test is to



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NOTE: Applied minimum back pressure depends on test temperature:

Test temperature Minimum back pressureF C psi kPa

212 100 100 690

250 121 100 690

300 149 100 690

350 177 160 1104

400 204 275 1898450 232 450 3105

WARNING: Do not use ni trous oxide cartr idges: under HPHT conditions it can detonate in thepresence of oil and grease.



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2.7RETORT ANALYSIS (O/W ratio)

In order to prevent retort error, it is important to use a variable temperature retort when testing an oilmud. Heat sample to the temperature required to distil water by raising the temperature to 160C(325F). After allowing the water sufficient time to distil over, then the temperature can be raised toensure all the oil is distilled. Again, gradually raise the temperature and hold where oil is distilling,

as there will be retort error due to flashing-off of oil at extreme temperatures.

It is important to realize that drilled solids can contain water within their mineral matrix. If a system

has sufficient drilled solids, water can be distilled at extreme temperatures, again, giving retort error.This could be a problem in a pure oil system because the results would indicate free water.

Equipment:1. 20 / 50 ml variable retort

2. Retort cylinder (% graduation)3. Steel wool, anti-seize grease

Procedure:

1. Fill the chamber with a freshly obtained mud sample, avoiding air bubbles entrapment intosample.

2. Place the lid on the chamber allowing any excess mud to escape.3. Remove the lid from the chamber being careful not to remove any fluid adhering to the lid.4. Add 5-6 drops of liquid steel wool or pack steel wool around the upper portion of the

i i h h lid l l ill i b il/ i



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Calculations: CORRECTED RETORT VALUES

Corrected retort values for solids and brine are calculated by using the volume increase factor:

F =)01.01( S

d

B

W

F = volume increase factor dW = water density (assume 1.000 sg)

B = brine density (from salt tables, sg) S = %w salt in brine (from salt tables, sg)

Then,

%SC =F

S%%BC = %W + (%S %SC)

%SC = corrected solids % %S = percent retort solids%BC = corrected brine % %W = percent water in liquid phase

Oil/brine ratio (O/B) is then calculated as follows:

O =O% 100



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2.8 LIME AND SALINITY

A. Excess Lime

It is also called whole mud Lime content.

Calculation:

LimeOM (ppb) = 1.295VSA LimeOM (kg/m 3) = 3.69VSA (a)

LimeOM = Ca(OH)2

VSA = ml of 0.1N sulfuric acid

B. Calcium Chloride and Sodium Chloride

It is the salt content in the whole mud. Oil based mud may contain both CaCl2 and NaCl.

Calculations:

CaCl2OM (mg/L) = 2.774CaOM (b)

CaCl2 (kg/m3) = 0.002774CaOM CaCl2 (ppb) = 0.000971CaOM



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C. Aqueous phase salt content

To determine salt content in the aqueous phase only (not in the whole mud).

Calculations:

WCaCl2 =

WNaClCaCl

CaCl

OMOM

OM

%2

2100

++

(f)

WCaCl2 = %w of CaCl2 in brine %W = % volume of water (from retort)

WNaCl =WNaClCaCl

NaCl

OMOM

OM

%2

100

++

(g)

WNaCl = %w of NaCl in brine %W = % volume of water (from retort)

The CaCl2 and NaCl concentration in the aqueous phase are therefore:

CCaCl2 (ppm) = 10000WCaCl2 CCaCl2 (mg/L) = 10000 WCaCl2 B (h)



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2.9 OIL/WATER RATIO AND SOLIDS

A. Corrected solids

It takes into account volume occupied by solids both in oil and in brine.

Calculation:

Volume percent of brine is calculated as follows:

%B =)(10 0[

%100

2CaClNa ClB WW

W

+

(a)

%B = %v of brine %W = %v of water (from retort)

The volume percent of corrected solids is therefore:

VCS = 100 (%O + %B)

VCS = %v of corrected solids %O = %v of oil (from retort)

B Oil/Water ratio (O/W)



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C. Average density of suspended solids

Drill solids consists both in low-gravity solids (LGS) and high -gravity solids (HGS).Average density of solids contained in OBM is calculated as follows:

Calculation:

S (ppg) =CS

BBO

V

VOd

345.8

345.8%100 (d)

O = oil base density (ppg) S = average density of solids (g/cm3)d = mud density (ppg) VCS = volume % of corrected solids

VB = %v brine B = brine density (ppg)

D. LGS and HGS

The %v of HGS and LGS is:

Calculation:



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2.10 RHEOLOGY

When measuring the rheology of oil based drilling fluid, generally near bottom hole temperatures areused. A thermo-cup is used in order to heat the drilling fluid. A temperature of 49C or 120F isnormally used.

Equipment (Method 1):1. Marsh Funnel

The procedure for obtaining viscosity of oil- and water-based fluid are identical.

Equipment (Method 2):1. FANN 6-Speed Viscometer Model 35 or equivalent (OFI model 800)

Procedure:

1. Place a sample of drilling fluid in a heat cup. Leave enough empty volume in the cup for the

displacement of the viscometer bob and sleeve.2. Heat the sample to the selected temperat ure. Intermittent or constant shear at the 600 rpm

speed should be used to stir the sample while heating to obtain a uniform sample temperature.After the cup temperature has reached selected temperature, immerse the thermometer into the

sample and continue stirring until the sample reaches the selected temperature.3. With the sleeve rotating at 600 rpm, wait for dial reading to reach a steady value (the time

required is dependent on the mud characteristics). Record the dial reading for 600 rpm.hif d i f di l di h d l d h di l di



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2.11 ACTIVITY MEASUREMENTS

An important aspect of the brine phase is referred to as "activ ity". The term activity, in a drillingsense, describes the tendency for the movement of water vapor from an area of low saltconcentration to an area of high salinity. The water activity (A w) is measured as a fraction of thevapor pressure of water or relative humidity.

In an invert emulsion drilling fluid the brine phase is not isolated from the formation by the oilphase. Water vapor may pass from the brine droplet into the formation or vice-versa depending uponthe osmotic pressure differential between the brine phase and the formation. The osmotic pressure of

the formation or brine phase is a measure of the activity and salinity of the formation and brine. Theconcentration of salt in the brine phase will largely determine whether water will flow from the brineto the formation, from the formation into the brine phase or whether there will be no net movementof water in either direction.

Equipment:1. A2101 AwQuick bench meter / HygroPalm Aw 1 hand held meter

Procedure:

1. Place sample in cup (clear plastic 5ml dish) provided up to the fill line.

2. Close cup with cover and place sample in the same general area as the probe to equalize thetemperature to ambient.

3. When sample is ready, remove cover from the sample cup and place the cup inside the holder.h b f h l h ld k h h b l h

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COMPLETION FLUIDS(CLEAR BRINES)



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3.1 DENSITY

Equipment (Method 1):1. Mud balance

The procedure is the same as for WBM and OBM.

Equipment (Method 2):1. Hydrometers set (ranging from 0.8 to 2.4 sg)

2. 500 ml glass cylinder3. Glass thermometer (0 100 C)

Hydrometers are more accurate than mud balance (accuracy: 0.002 g/cm3). Density measurementis greatly affected by temperature.

Procedure:

1. Pour a sufficient brine volume into a 500 ml glass cylin der.2. Record sample temperature.3. Place the adequate hydrometer into the cylinder: it must float freely away from the walls of

cylinder.

4. If hydrometer touches the bottom of cylinder, choose another one.5. Read the density value at the point at which brine surface cuts hydrometer stem scale.



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3.2 TURBIDITY

Brine turbidity is due to suspended solids, insoluble in water. Quantity, type and particle sizedistribution of solids affect brine quality.Turbidity is expressed as Nephelometric Turbidity Units (NTU): low NTU values indicate that brineis clear (low solids content).

Equipment:1. Turbidity meter (HANNA, mod. HI 93703) or equivalent.

Turbidity range: Low-range: 0 50 NTU

High-range: 50 1000 NTU

Turbidity is not a measure of concentration of suspended solids, but a measure of their particle sizedistribution (PSD), shape, refractive index. Estimation of solids concentration by turbidity

measurement can be done only if a calibration curve is generated.Coarse solids (greater than 200 mesh, 75 m) are not determined with this method.

Procedure:

1. Collect a 100-ml sample of brine and pour it into a 200 mesh (75 m) screen. Recover thesieved brine.

2. Turn on the instrument and fill a clean cuvet with the filtered sample up to inch (0.5 cm)from its rim.

3. Tighten the cap and wipe the cuvet with a clean paper. Do not touch the cuvet with fingers!l h i h ll d h k h h h i i i d l i h



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3.3 CRYSTALLIZATION TEMPERATURE

The actual crystallization temperature (TC) of brine is the temperature at which a solid (salt or ice)will begin to form out of solution if given sufficient time and proper nucleating agents.TC is the temperature at which the brine is saturated with one or more salts that it contains. At thistemperature, the least soluble salts solubility is exceeded and crystallizes. Cooling brine below TC

results in additional formation of salt crystals.Salt precipitation due to temperatures lower than T C can lead to several problems (settling, plugging) and brine viscosity rises. During crystallization, brine volume doesnt expand (water expandswhen becomes ice).

TC depends on brine density: TC decreases until salt saturation is reached; when salt concentration isgreater than saturation, then TC increases with salt concentration.Several TC can be determined for brines:

FCTA (First Crystal To Appear): it is the temperature at which visible crystals start toform;

TCT (True Crystallization Temperature): it is the maximum temperature reachedfollowing the super-cooling minimum. If no super-cooling occurs, TCT = FCTA; it is the

best measure of TC for a brine; LCTD ( Last Crystal To Dissolve): it is the temperature at which, during heating, crystals

disappear.

Super-cooling effect appears when brines are cooled below T C and no crystals form due to lack ofnucleating agents (BaO, Ba(OH)2, CaCO3, bentonite).When crystals begin to form at FCTA, the heat released by the crystallization process increases brine



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3.4 CHEMICAL ANALYSIS

Chemical analysis can be done directly on a measured volume of brine sample.

A. Calcium

The procedure is the same described for Calcium hardness in WBM.

Equipment :

1. Titraver 4000 or EDTA 0.1M2. Calver II indicator or murexide (to distinguish calcium from magnesium)3. Sodium hydroxide (0.1N) solution (to distinguish calcium from magnesium)4. Graduated pipettes (1 ml)5. Distilled water


Procedure:

1. Using a pipette, measure 1.0 ml of brine into a white titration dish and dilute with a smallamount of distilled water.

2. Add 2 drops of 0.1N NaOH (sodium hydroxide). Solution pH must be approx. 12 13.

3. Add several grains of calver II (or murexide) and swirl or stir to mix.4. Using a pipette, titrate with titraver (or EDTA) to a colour change from red to blue.



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B. Chlorides and Bromides

The procedure is the same described for chlorides in WBM.

Equipment:1. Silver nitrate solution:

- 0.1N (or 0.0282N) for low chloride concentrations- 1N (or 0.282N) for high chloride concentrations

2. Potassium chromate indicator (5% solution)

3. Sulfuric acid (N/50)4. Phenolphthalein indicator5. Graduated pipettes (1 ml)6. Titration beaker (100 ml)


Test Procedure:

1. Measure 1.0 ml of brine sample into a white titration beaker and dilute to convenient volumewith distilled water.

2. Add a few drops of phenolphthalein. If a pink colour develops add N/50 sulfuric acid until thepink colour completely disappears (it is not necessary to record the volume of N/50 sulfuric

acid added)3. Add 4 drops of potassium chromate to obtain a yellow colour.4 Add silver nitrate while stirring until the colour changes from yellow to orange red (brick red)



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2. For CaCl2, CaBr2, ZnBr2 brines:

kg/m3

= VTF

VT = ml of Silver Nitrate F = correction factor

Silver Ni trate0.1N 1.0N 0.0282N 0.282N

Cl-= 7.09 Cl

-= 70.9 Cl

-= 1.99 Cl

-= 19.9

Br-= 15.98 Br-= 159.8 Br-= 4.50 Br-= 45.0

CaCl2 = 11.10 CaCl2 = 111.0 CaCl2 = 3.13 CaCl2 = 31.3

CaBr2 = 19.99 CaBr2 = 199.9 CaBr2 = 5.64 CaBr2 = 56.4

Correction factors.

Issue 1: May 2004 AVA Products AnalysisRev. 0 Page 72


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-4-

DETERMINATION OFAVA PRODUCTS



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4.1 AVAGLYCO, AVAGLYCO MP

The most suitable methods for rig site glycol analysis are refractometric analysis and cloud pointdetermination.

The value of refractive index is affected by many factors, such as solids, organic polymers (PAC,CMC ) and inorganic salts.In a mud system, glycol concentration is determined measuring the refractive index of filtrate with arefractometer; it is converted to glycol concentration through a calibration graph.

The use of a commercial refractometer with 0 32 (or 0 18) Brix scale reading is very useful(Brix degrees can be simply converted in refractive index).

The cloud point temperature depends both on glycol and salt concentration (KCl, NaCl, ).

Determination of cloud point in mud system can be quite difficult especially if there are suspendedsolids.Tables can help in evaluating cloud point of mud system, as function of glycol and salt

concentrations.

A. Refractive index method

Equipment:1. Portable Refractometer2. Plastic Pasteur



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NOTE: I f refractometer used displays refr active index instead of Brix degrees, then thefollowing corr elati on cart can be used.

Brix n20

Brix n20

Brix n20

Brix n20

0 1.33299 26 1.37406 52 1.42433 78 1.485521 1.33442 27 1.37582 53 1.42647 79 1.488102 1.33586 28 1.37758 54 1.42862 80 1.490713 1.33732 29 1.37936 55 1.43080 81 1.493334 1.33879 30 1.38115 56 1.43299 82 1.49597

5 1.34026 31 1.38296 57 1.43520 83 1.498626 1.34175 32 1.38478 58 1.43743 84 1.501297 1.34325 33 1.38661 59 1.43967 85 1.503988 1.34476 34 1.38846 60 1.44193 86 1.506719 1.34629 35 1.39032 61 1.44420 87 1.50944

10 1.34782 36 1.39220 62 1.44650 88 1.5121911 1.34937 37 1.39409 63 1.44881 89 1.51496

12 1.35093 38 1.39600 64 1.45113 90 1.5177513 1.35250 39 1.39792 65 1.45348 91 1.5205614 1.35408 40 1.39986 66 1.45584 92 1.5233815 1.35568 41 1.40181 67 1.45822 93 1.5262216 1.35729 42 1.40378 68 1.46061 94 1.5290917 1.35891 43 1.40576 69 1.46203 95 1.5319618 1 36054 44 1 40776 70 1 46546



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4.2 AVAPOLYSIL, AVASILIX, AVASHALESTOP/ACT,AVAEASYDRILL

To determine AVAPOLYSIL, AVASILIX 39 or AVASILIX 22, AVSHALESTOP/ACT andAVAEASYDRILL concentration in WBM, a colorimetric method for silica is used.

At pH 1 2 soluble silicates react with ammonium molibdate to form silico-molibdic acid; this acidis reduced by methol (n-p-methylaminophenol sulphate) in a silico-molibdic blue complex.

Chemical reaction that takes place is the following one:

H4SiO4 + 12 H2MoO4 H4Si(Mo3O10)4 + 12 H2O Met ho l Blue complex

Equipment:1. Silica kit (Carlo Erba Idrimeter or equivalent)

2. Bi-distilled water3. Graduated Pipette (5 ml)

Procedure:

1. Pour 2 portions of 5.0 ml filtrate into the 2 vials (left side: blank right side: sample)2. Into the right vial add 4 drops of Reagent A. Shake the sample and wait for 10 min.3 Add i t th i ht i l 4 d f R t B d 4 d f R t C



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4.3 AVACLAYBLOCK, AVAFASTDRILL,AVASHALESTOP, AVAPOLYMER 5050

Determination of AVACLAYBLOCK is based upon a colorimetric method and is therefore a semi-quantitative analysis.

Equipment:1. Boric acid 4%

2. Iodine/Iodide (I2/I-

) solution (indicator)3. Graduated pipette (5 ml)4. Beaker (100 ml)5. Distilled water

Procedure:

1. Prepare at least 3 standard solutions with concentration ranging from 10.0 to 40.0 kg/m3.

Standard solutions must be as close as possible to filtrate composition.2. Add to these solutions few drops of indicator.3. To 5.0 ml of filtrate, add 1.5 ml of boric acid solution and few drops of indicator.4. Wait for 15 minutes.

5. Compare color with the one obtained with standard solutions.



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4.4 AVADES 100

AVADES 100 is based on triazine derivatives; it reacts rapidly and irreversibly with H2S.Test is therefore used to determine Avades 100 excess in WBM. This quantity can be estimated bydetection of total formaldehyde in filtrate. Quantity of formaldehyde is directly related to presence of

free (non-reacted) triazine.This is a colorimetric test, based on the following chemical reactions:

CH2O + Na2SO3 CH2O4SNa2CH2O4SNa2 + 2HCl 2NaCl + SO2 + H2O + CH2O

Although test is semi-quantitative, results can be interpreted as follows:

Positive test (presence of formaldehyde): Avades 100 is still present in mud (no H2S ispresent)

Negative test (absence or little presence of formaldehyde): Avades 100 has been consumedtotally by H2S. It is necessary add it again to the mud in order to scavenge remaining quantity

of H2S.

Equipment 1:1. Formaldehyde kit (Hanna mod. HI 3838 or similar)

Equipment 2:1. Reagent 1: Alizarin Yellow solution (indicator)



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Calculations:

If High range (0 10 %) method is used:

AVADES 100 (kg/m3) = VT460

If Low range (0 1 %) method is used:

AVADES 100 (kg/m3) = VT46

VT = ml of Reagent 3 used

NOTE: Factors used in formulas are indicatives.

INTERFERENCES: A. Sodium Sulfi te (DEOXY SS):

DEOXY SS can react with formaldehyde coming f rom Avades 100: thisreaction i s infl uenced by pH. Under alkali ne or neutral conditions (as indri ll ing fluids), formaldehyde is released from Avades 100 slowly andtherefore formaldehyde concentration is low.DEOXY SS is therefore available for scavenging oxygen.

B. Fil trate alkalini ty:



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4.5 AVAPOLYOIL (DEEPDRILL)

AVAPOLYOIL (DEEPDRILL) is a blend of polyhydroxyl alcohols; its determination in drillingfluids is based upon a refractometric method.


Procedure:

Analysis of filtrate chlorides must be performed prior to begin testing.1. Prepare at least 3 standard solutions with concentration ranging from 80.0 to 150.0 kg/m

3.

Standard solutions must be as close as possible to filtrate composition.2. Put a drop of distilled water on refractometer: it must indicate 0 Brix. If not so, adjust

calibration screw until 0 Brix are displayed.

3. Put a drop of standard solutions at different concentrations and read.4. Draw a calibration curve using the standard solutions.5. Put a drop of filtrate and compare with calibration curve.

Calculation:

A l il (% ))000138.0()58.2( ClR



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4.6 AVABIOLUBE

AVABIOLUBE is polysorbitol-based compound; its determination in drilling fluids is based upon arefractometric method.


Procedure:

1. Prepare at least 3 standard solutions with concentration ranging from 20.0 to 600.0 kg/m3.

Standard solutions must be as close as possible to filtrate composition.

2. Put a drop of distilled water on refractometer: it must indicate 0 Brix. If not so, adjustcalibration screw until 0 Brix are displayed.

3. Put a drop of standard solutions at different concentrations and read.

4. Draw a calibration curve using the standard solutions.5. Put a drop of filtrate and compare with calibration curve.

NOTE: Clean refractometer display with adsorbent paper after eachmeasurement.



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4.7 DEOXY DEHA

DEOXY DEHA is oxygen scavenger product based on amine compounds. Excess of product indrilling fluids must be guaranteed and therefore its determination is important.Test is based on a colorimetric reaction and is performed according ASTM D-5543/94 procedure.

Equipment:1. Dissolved oxygen kit (Chemetrics code K-7501

or similar): 0 1 ppm O2

Procedure:

1. Insert the glass ampoule into the mud sample with the pointed end down.

2. Allow the sample to flow in at least 5 min.3. Gently press the ampoule toward the wall of sampling tube to snap the tip and remove the

ampoule, keeping the tip down, immediately after filling is complete.

4. Place a finger over the broken tip (CAUTION: glass may be sharp). Invert the ampouleseveral times to allow mixing of content.5. Compare color developed (pink) in the ampoule by placing it in the center of the comparator,

with the flat end downward.

6. Rotate wheel until the color in the ampoule matches the one of the comparator.


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CONVERSIONS, CALCULATIONS& PROPERTIES

SECTION II

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Issue 1: May 2004 Index

Rev. 0 Page i

T A B L E O F C O N T E N T S


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Page number

CONVERSION FACTORS.....................................................................................................................1

GENERAL FORMULAS .........................................................................................................................4PILOT TESTING GUIDELINES...........................................................................................................7

DENSITY ADJUSTMENTS....................................................................................................................9Density adjustment with barite...................................................................................................................9Density adjustment with calcium carbonate...............................................................................................10Mud volume to prepare 1 m3 of mud weighted with barite.........................................................................11Density reduction with water......................................................................................................................12Density reduction with Diesel oil ...............................................................................................................13Density reduction with LT oil .....................................................................................................................14

COMPLETION FLUIDS .........................................................................................................................15

Brine dilution ..............................................................................................................................................15Weighting brines .........................................................................................................................................16

Brine density table ......................................................................................................................................20Brine calculations .......................................................................................................................................22Temperature correction factors..................................................................................................................28Volume expansion correction .....................................................................................................................31

Properties of sodium chloride solutions .....................................................................................................32Properties of potassium chloride solutions ................................................................................................33Properties of potassium bromide solutions ................................................................................................34Properties of potassium carbonate solutions .............................................................................................35Properties of sodium bromide solutions .....................................................................................................36

Properties of potassium sulfate solutions ...................................................................................................38Properties of calcium chloride solutions ....................................................................................................39Properties of calcium bromide solutions ....................................................................................................42

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Issue 1: May 2004 Index

Rev. 0 Page ii

Properties of sodium/calcium chloride blends ...........................................................................................44Properties of calcium chloride/bromide blends .........................................................................................45Properties of zinc/calcium bromide blends ................................................................................................46Properties of zinc/calcium bromide/calcium chloride blends.................................................................... 47


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