3. data source.pdf

7/27/2019 3. DATA SOURCE.pdf

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Data source

Section 3


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Outline

1. Pressure data source

2. Fluid gradient

3. Vertical stress/overburden stress4. Minimum horizontal stress (fracture pressure)


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Data source Hierarchy

Repeat formation tester (RFT, FMT, MDT)

Formation interval test (FIT)

Drill stem test (DST)Well or pressure kick

Connection gas

Measurement whilst drilling (MWD/LWD)

Mudweight

Drilling exponent

Swarbrick, 1999


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MDT tool


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RFT/MDT


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RFT data chart


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Analog recording

Pressure build-up: formation permeability/mobility


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Accuracy of MDT/RFT

Quartz gauge:

error about 15 psi (Ireland et al., 1992)

New generation of quartz gauge

(combinable quartz gauge/CQG)

error about 2.5 psi


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Remarks on pressure data

TVDSS

(ft)TOOL GAUGE

FP

(psi)

EMW

(gr/cm3)

MOB

(mD/cp)FA

FLUID

LOGMARKER REMARK DATE

7449.37 RFT QG 3292 1.01 HC G 1a-a GOOD 6/2/1991

7449.37 RFT QG 3293 1.01 61 N/A G 1a-a GOOD 6/2/1991

8003.04 RFT QG 3610 1.04 14 N/A G 1d GOOD 6/2/1991

8608.20 RFT QG 3906 1.04 4.3 N/A G 1g GOOD 6/2/19918646.74 RFT QG 3854 1.02 876 N/A G 1h GOOD 6/2/1991

8670.52 RFT QG 3853 1.02 273 N/A G 1h GOOD 6/2/1991

8682.00 RFT QG 3854 1.02 974 N/A G 1h GOOD 6/2/1991

8695.12 RFT QG 3855 1.02 938 N/A G 1h GOOD 6/2/1991

8708.24 RFT QG 3856 1.02 45 N/A G 1h GOOD 6/2/1991

9898.81 RFT QG 4430 1.03 N/A G 2g N.S 6/2/199110907.74 RFT QG 5291 1.12 N/A G 4a S.C 6/2/1991

10950.05 RFT QG 5384 1.13 1.4 N/A G 4b GOOD 6/2/1991


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Remarks

Good: reliable pressure data

NS: not stabilised (not enough time to

directly determine pressure value)

SC: supercharged unreliable pressure

data due to mud invasion

Tight: unreliable pressure data due to tightreservoir


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3000 4000 5000 6000 7000

7000

8000

9000

10000

11000

12000

13000

Pressure (psi)

Depth(ft)

Supercharged


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2. Fluid gradients

g

dz

dPw


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Specific

gravity

API gravity Normal

hydrostatic

grad. (psi/ft)

Total

Dissolved

solids (ppm)

1.14 (brines) -7.50 0.494 210,000

1.12 -5.20 0.485 175,800

1.10 -2.70 0.476 143,500

1.05 30 0.455 69,500

1.00

(fresh water)

100 0.433 zero

0.95 170 0.411

0.9 250 0.390

0.85 (light oil) 350 0.3680.8 450 0.346

0.7 600 0.303

0.4 (gas) 0.130

Simplified from Dahlberg, 1982


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Water grad. : salinity measurement

HC grad. : API measurement

Water & HC: could be inferred from

pressure

depth plot, if the pressuremeasurement close enough

Fluid gradients


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0 2000 4000 6000 8000 10000

0

2000

4000

6000

8000

10000

12000

14000

Example: Kutai BasinPressure (psi)

Depth

(ft)

0.433 psi/ft


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Some examples of hydrostatic gradient

Region Hydrostatic gradient

(psi/ft)Anadarko 0.433

California 0.439

Gulf of Mexico 0.465

Mackenzie Delta 0.442

Malaysia 0.422

North Sea 0.452

Rocky Mountains 0.436

Santa Barbara Channel 0.452

West Africa 0.442

West Texas 0.433

Kutai Basin 0.433


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HC gradientPressure (psi)

Depth(ft)

Water: 0.433 psi/ft

HC: 0.1 psi/ft

HC RFT point

Water RFT point


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HC gradientPressure (psi)

Depth(ft)

HC RFT point

Water RFT point

Variable HC-water contact?


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Indication of hydrodynamic trap:

will be discussed later


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3. Vertical stress/overburden stress


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Fluid

Overburden

()

Rock matrix

=p

(pore pressure)

+ (effective stress)

b

gzb g

dz

db


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Average density down to 3 4 km:

2.3 g/cm3

g

dz

db

pa/m23000smkg23000102300 22

dz

d

psi/ft1KPa/m23 dz

d


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1 psi/ft

Vertical stress/overburden stress


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Example: Shelf, Kutai Basin

1 psi/ft only at depth

Ramdhan & Goulty, 2010


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Example:

Baram Delta

Variation of

vertical stress

due to uplift and

undercompaction

Tingay et al., 2003

W ld id l


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World wide example

Mouchet and Mitchel l , 1989


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Vertical stress from wireline logs

The most reliable: density log

Sonic, resistivity, etc.

Density (g/cm3)


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Example of reasonably

good density log

- Oil-based mud

- Measurement every 0.5 ft- No density data in the

shallow section

Density (g/cm3)

Depth(ft)

Trend 1

Trend 2

Caving?

D it ( / 3) D th (ft)


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1.50

1.87

2.02

2.13

2.22

2.29

2.35

2.40

2.44

2.49

2.52

2.56

2.60

2.62

Density (g/cm3) Depth (ft)

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000

0

n

ib

zg1

Exercise


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1.50

1.87

2.02


1000

2000

3000

0 1

2

3

@2000@3000

@1000 = 1

@2000 = 1 + 2

@3000 = 1 + 2 + 3


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1.50

1.87

2.02


1000

2000

3000

0

Depth (ft) n = bgz (Pa) n (Pa) n (psi)

1000 1500 x 9.8 x 1000 x 0.3048

= 44805604480560

650

2000 1870 x 9.8 x 1000 x 0.3048= 5376672

9857232

1429

3000 2020 x 9.8 x 1000 x 0.3048

= 603382115891053

2304


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0 2000 4000 6000 8000 10000 12000 14000

0

2000

4000

6000

8000

10000

12000

14000

Pressure (psi)

Depth

(ft)

1 psi /ft

The realoverburden gradient

1 psi/ft is only

at depth


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0 2000 4000 6000 8000 10000 12000 14000

0

2000

4000

6000

8000

10000

12000

14000

Pressure (psi)

Depth(ft)

1 psi /ft

Shelf overburden

Deep water overburden

Mud line

Deep water overburden profile


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4. Minimum horizontal stress (fracture pressure)


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Leak-off test

White et al., 2002

E l K t i B i


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Example: Kutai Basin


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Example: world-wide

Breckels and Eekelen, 1982

Power law: bH

az


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Some notes on minimum horizontal stress

(fracture pressure)

The deeper, the greater the gradient

following power law

Couple pore pressure fracture pressure

Overpressure-induced

increase fracture pressure Production-induced

reduce fracture pressure


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Review


Direct: RFT/MDT, FIT, DST

Indirect: drilling parameters

2. Hydrostatic fluid and hydrocarbon

gradients

Fluid density Pressure data


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Review

Vertical stress gradient: density

Minimum horizontal stress/fracturegradient: LOT


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Question?

3. data source.pdf

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