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1. Introduction to ASP flooding

2. Function of ASP Components

3. ASP Problems and Challenges

4. Typical Injection Scheme

5. How to Success

6. Design Parameters for ASP Process

7. Surfactant Adsorption

8. Development History Of ASP Flooding

9. ASP Performance from Tanner Field

10.ASP Projects in Different Fields

11.ASP Chemical Costs

Presentation Outline

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Introduction to ASP Flooding

Alkali-surfactant-polymer (ASP) is considered to be themost promising and cost-effective chemical method inrecent years.

The new technique of ASP flooding has been developed onthe basis of alkali, surfactant, and polymer floodingresearch in 1970s and 1980s.

ASP flooding uses the benefits of the three floodingmethods simultaneously, and oil recovery is greatlyenhanced by increasing the capillary number, decreasinginterfacial tension, enhancing microscopic displacingefficiency, and improving the mobility ratio

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Introduction to ASP Flooding

Mobility control is critical. According to Malcolm Pitts, 99%of floods will fail without mobility control.

Floods can start at any time in the life of the field.

Good engineering design is vital to success.

Laboratory tests must be done with crude and reservoir rockunder reservoir conditions and are essential for eachreservoir condition.

Oil companies are in the business of making money and arerisk adverse so....Process design must be robustProject life must be shortChemicals must not be too expensive

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High pH and/or ASP Flooding

Surfactant adsorption is reduced on both sandstones andcarbonates at high pH.

Alkali is inexpensive, so the potential for cost reduction islarge.

Carbonate formations are usually positively charged atneutral pH, which favors adsorption of anionic surfactants.However, when Na2CO3is present, carbonate surfaces(calcite, dolomite) become negatively charged andadsorption decreases several fold.

Alkali reacts with acid in oil to form soap, but not all crudeoils are reactive with alkaline chemicals.

High pH also improves microemulsion phase behavior.Open

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Introduction to ASP Flooding

In ASP flooding, Two Surfactants From Different Sources

Natural Soap (Naphthenic Acid + Alkali)A hydrophobic surfactantGenerated in situ

Synthetic surfactantA hydrophilic surfactantInjected as the surfactant slug

Two Surfactants

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Function of ASP Components

The function of the alkaline: To form in-situ surfactant. To reduce the interfacial tension between crude oil and the injection

solution. To reduce the amount of surfactant adsorption onto formation.

The function of the surfactant: To produce an ultra low interfacial tension between the

crude oil and the injection solution

The function of the polymer: To drive ASP slug. To increase the sweep efficiency.

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ASP Problems and Challenges

Challenges:1) Chemical cost and availability

2) Platform space limited

3) Alkali consumption by Ca and Mg either in the reservoir water

or in the injection water.

4) Plugging of injection wells

5) Corrosion and Scaling problems

Several variations ASP SAP PAS

Injected as premixed slugs or in sequence

Solutions may be mixed onshore and

shipped

Water drive

Alk

ali

Su

rfacta

nt

Polymer

Oil bank

SPE 127714 (2010), SPE 129256 (2010), IPTC 13397 (2009)

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Typical Injection Scheme

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How to Success

The success of this process depends on the identificationof the proper alkali, surfactant, and polymer and on theway they are combined to produce.

Compatible formulation that yields good crude oilemulsification.

Low chemical losses

Good mobility control

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Design Parameters for ASP Process

Fluid-Fluid Interaction

Interfacial Tension Mechanism

Phase behavior test

Fluid-Rock Interaction

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Fluid-Fluid Interaction

The compositions of the brine such as sodium salt, calcium, andMagnesium have a significant effect on the chemicals added.

When the chemicals (alkali, surfactant, polymer) added to the injectionwater, directly will be attacked by the divalent metal cations such as Caand Mg ions.

Therefore, it is impossible to maintain the preferred chemicalsconcentrations in the flooding water. Therefore, the chemical will not acteffectively to increase the capillary number.

In ASP flooding process, the complex interactionsbetween the various injected chemicals andreservoir fluids is classified as fluid/fluidinteraction or compatibility test.

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Description Of The Problem

Divalent metal cations (Ca and Mg)

precipitation

Surfactant adsorption Well pores blocking

Reaction between the fluids and rock

surface

Reservoir

fluids

sand

ASP

Crude oilASP

Production

well

Injection

well

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Fluid-Fluid Interaction

Several methods have been made to remove the Ca and Mg ions fromthe injection brine or/and reservoir brine.

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Surfactant Adsorption

The most important cause of ionic surfactants adsorbing onto a solid isoften the electrical interaction between the charged solid surface andsurfactant ions.

The forces of adsorption due to electrostatic attraction or repulsionbetween a charged solid surface and the charged surfactant can play agoverning role in the system with oppositely charged solid andsurfactant.

The amount of adsorbed surfactant depends on:

Surfactant character Rock properties pH Salinity

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Surfactant Adsorption

The salinity may change the electrical potential of surfacesites for the adsorption.

The change in the pH of the aqueous phase usuallyindicates changes in the adsorption of ionic surfactants oncharged solid surfaces. The sand surface will be positivelycharged under a low pH conditions and negatively chargedunder high pH conditions.

Adsorption of anionic surfactant on sandstone woulddecrease with an increase of pH because the increasing OH-makes the sand surface more negative and electrostaticrepulsive force will drive more anionic surfactants tosolution.

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Surfactant Adsorption Isotherm

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Alkaline Surfactant Polymer Field

Projects Since 1980

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Development History Of ASP Flooding

Daqing Oil Field. Po pilot (China) (SPE 35383)

Pilot Injection scheme: 3 slugs (1994 1996)

1. ASP slug: 32.7% PV (1.25%; alkali, 0.3%; Surf, 1200 ppm polymer)

2. Polymer slug: 27.3% PV 800 ppm

3. Fresh water (water cut 98%)

ASP recovery: 20% OOIP

Fresh water was used to prepare the ASP slug

Viraj oil field (India) (SPE 88455)

Pilot Injection scheme: 4 slugs (2002 - 2004)

1. Preflush: 20% PV fresh water

2. ASP slug: 20% PV (1.5%; alkali, 0.2%; Surf, 800 ppm polymer).

3. Mobility buffer: 30% PV (10% PV with 600 ppm, 10% PV with 400 ppm, and 10% PV with 200 ppm.

4. Chase water: 60% PV formation water.

ASP recovery: 18% 24% OOIPOpen

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ASP Performance from Tanner Field

ASP Flood -40% Oil Cut of Waterflood

Formation MinnelusaBDepth 8,750 ftTemperature 175 FPore Volume 2,528 MbblThickness 25 ftAverage Porosity 20%Average Permeability 200 mdOil API Gravity 21Oil Viscosity 11 cpWater Viscosity 0.45 cpMobility Ratio 3.2

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ASP Performance from Tanner Field

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ASP Performance from Tanner Field

Recovery Summary through July 2005

Ultimate Oil Recovery 65.0 %OOIP

Primary and Waterflood to 3% Oil Cut 48.0 %OOIP

ASP Increment Recovery 17.0 %OOIP

Primary and Waterflood to 7/2003 -26% Oil Cut 36.5 %OOIP

Cost per Incremental Barrel

(Includes Chemical and Facilities) $4.49 (estimated)

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ASP Projects in Different Fields

White Castle, Q sand

West Kiehl, MinnelusaLower Bsand

Cambridge Minnelusa

Gudong

Daqing, West Central Saertu

Daqing, XF

Karamay

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ASP Projects in Different Fields

Alkali and Surfactant Concentrations

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ASP Projects in Different Fields

Alkali-Surfactant Slug Size

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ASP Projects in Different Fields

Incremental Oil Recovery

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ASP Chemical Costs

1.5% Na2CO30.2% sulfonate1000 ppm polymer0.3 PV slug0.2 PV drive 0.5 bbl inc. oil/bbl slug

Na2CO3: @ $0.0425/lb = $0.45/bbl oilSulfonate: @ $0.68/lb = $0.95/bbl oilPolymer: @ $1.50/lb = $1.75/bbl oil

Total chemicals: = $3.15/bbl oil

ASP slug specifications

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