Missouri Energy Summit 2009 Preformed Particle Gel PPG

Missouri Energy Summit 2009 Preformed Particle Gel (PPG) for Conformance Control Baojun Bai, Yongfu Wu Petroleum Engineering Missouri University of Science and Technology March 23, 2009

Outline n n n Oil Production Mechanisms Enhanced Oil Recovery (EOR) Targets Preformed Particle Gel (PPG) for Conformance Control n n n Gel Treatments Advantage of PPG Treatments Enhanced Oil Recovery Mechanisms Applications Future Research Summary

Oil Production Processes

Oil Recovery Mechanisms

EOR Targets EOR Potential in the U. S. A Original Oil in Place in USA: 649 Billion Barrels

EOR Potential in the World

The Four Key Issues to be Resolved to Maximize Oil Recovery

Preformed Particle Gel (PPG) for Conformance Control

What is Preformed Particle Gel (PPG) (a) Before swelling (b) After swelling Cross-linked polyacrylamide powder SUPER ABSORBENT POLYMER

Why Gel Treatment n Excess water production is the most serious problem to reduce oil production as oilfields are maturing. n Improved sweep efficiency has become the most important target to improve oil recovery. n Gel Treatments are often the best choice to mitigate channeling through fractures and super-K streaks

What is Gel? Gelant (polymer/monomer+crosslinker +additives) Gel

Gel Treatment to Block/Reduce Water Flow through High Permeability Zone/Streak Near Wellbore Treatment (no crossflow) In-depth Gel Treatment (thick heterogenous layer with crossflow) KL Gel Kh KL KL Gel K h

Gels Used for Conformance Control n In-situ gel systems: Gelant is injected into formation and gel is formed under reservoir conditions after placement. Gelation occurs in the reservoir. n Preformed gel systems: gel is formed in surface facilities before injection, then gel is injected into reservoirs. No gelation occurs in reservoir.

A Newer Trend in Gel Treatment is Using Preformed Gels n Inherent disadvantages of In-Situ Gel § Crosslinking reactions are strongly affected by n n Shear by pump, wellbore and porous media Adsorption and chromatography of chemical compositions Dilution of formation water Possible damage on unswept low permeability oil zone of in-situ gel

Current Preformed Gel Systems n Preformed Bulk Gel: Dr. Seright/NMT, Robert Sydansk n Micro Particle Gel: µm-sized particle by Zaitoun et al/IFP. One application in a gas storage well n Bright Water®: Nano particle by Chevron, BP and Nalco Ten plus well pilot tests. n Preformed Particle Gel: mm-sized Grained particle, Bai et al, bout 2, 000 treatments

PPG Products n Size Adjustable: um-mm n Swelling Ratio: 30 200 times original n Salt Resistance: All salt types and concentrations are acceptable n Temperature Resistance: High, to 110 ºC n Long-term Stability: more than 1 year below 110 ºC.

EOR Mechanisms of PPG Treatment Oil Recovery ER=ED×EA×EV n ER=Recovery Efficiency n EV=Vertical Sweep Efficiency n EA=Areal Sweep Efficiency n ED=Displacement Efficiency Biggest Impact – Selective Plugging Some Effect

Experimental Results of Parallel Core Flooding (Vertical Heterogeneity Model) No. Permeability S 1 Split of Flow (percent) Oil Recovery ( 98% water cut) (Darcy) Before (%) after (%) before (%) after (%)） 8. 23 91 20 70 75 0. 54 9 80 22 54 KL=0. 54 D Kh=8. 23 D Total Oil Recovery Before (%) After (%) 46. 8 64. 9

Areal Sweep Efficiency Improvement MICROMODEL DEMONSTRATION water glass PPG oil drop 3 cm a. Remaining oil distribution in main stream Before PPG Inj. More water diverted to corner after PPG injection After PPG Inj. b. Oil distribution at corner – Now lower

Experimental Results from Single Sandpack Demonstrates Improved Displacement Efficiency Core No. K (D) PPG Size (mesh) Swi (%) Oil Recovery 1 (%) Oil Recovery 2 (%) Increased Oil Recovery (%) No 1 22. 5 250 22. 4 62 73 11 No 2 20. 6 160 23. 2 64 74 10 “ 1” refers to oil recovery from water flood before PPG injection “ 2” refers to total oil recovery from both water flood and PPG treatments

Field Applications n n n About 2000 treatments so far Reservoirs: n Naturally fractured reservoirs n Reservoirs without initial or hydraulic fractures. n Temperature: 30~110 ºC n Salinity: 2, 900 ~ 300, 000 mg/L PPG amount: 1, 000 ~120, 000 lbs/well, commonly 15, 000 -40, 000 lbs/well.

First pilot in Zhongyuan, SINOPEC Treatment Results Increased Oil 29, 151 bbl Oil incr. per PPG 0. 3 bbl of oil per lbs of PPG The performance of center producer connected with W 51 -75 and P-72

Future Research n Swollen particle transport mechanisms through high permeability zones and fractures. n Development of nano- or micro-sized swelling rate controllable particle gel. n Combination of PPG treatment and other EOR methods to enhance overall oil recovery.

Summary n Up to 65% reserve is remained after waterflood. n EOR should be considered, and can extract up to additional 25% OOIP. n PPG treatment overcome the distinct disadvantage of traditional in-situ gel treatments. n PPG treatment is a cost-effective method to improve oil recovery and reduce water production

Acknowledge n Financial Support from Research Partnership to Secure Energy for America (RPSEA) under DOE contract n Missouri University of Science and Technology