Case Study in Middle East, Improve Heavy Oil Production and Recovery by Reservoir Modification as Alternative Technology to Steam and Miscible Gas Injection

Abstract

Abstract Increasing oil production and recovery for Heavy Oil can be achieved by reducing oil viscosity. With reference to Darcy law, reducing the oil viscosity results in an increase in oil productivity. The current technologies for reducing viscosity are Steam injection and Miscible Gas (hydrocarbon or carbon dioxide) injection. However both steam and miscible gas has technical and economic limitations, and an alternative technology is required to extend beyond the limitations in both steam and miscible gas injection. The technology described herein is based on reservoir fluid and rock modification by chemical technology approach. Reservoir modifications are made by ability to mix between oil and water, and the mixed viscosity is designed to be reduced to close to, but higher than, water viscosity. Because the viscosity is still higher than water viscosity, the fluid flow becomes slower and will have enough time to react with oil and divert to the oil bank. When the modified chemical is diverted to the oil bank, then wettability alteration acts to peel out oil from the rock surface and has ability to pass through pore throatand hence flow to producing oil well. The research programewasconducted by mimicking reservoir behaviorby implementing mixture viscosity sensitivity performance test, imbibition tube test and coreflood test. The tests are implemented usingactual reservoir oil, water and rock. The result of viscosity reduction is able to reduce oil viscosity from more than 376 cp at reservoir temperature to less than 10 cp mixture viscosity at temperature between 60 and 90° C. For comparison, steam injection is able to reduce viscosity of heavy oil to become less than 10 cp, but requires a temperature of 350° C instead of 60 to 90° C. The imbibition test has shown incremental oil recovery at 14.7 psi (atm pressure) of two times that of reservoir water only, while the laboratory result with coreflood shows additional recovery after chemical injection of 30% to 50% beyond primary and water injection stage. The implementation is technically simple and it is able to be conducted at relatively low cost. The result from implementation by well basis injection yielded a significant increase in oil production. By sharing this road map experience from laboratory result to field implementation of the new method of chemicalstimulation forheavyoil production, it provides an alternative to improve production and recovery of heavyoil, especially in the Middle East.