Formula system of reduce pressure and increase injection working fluid in Tamtsag oilfield

Enhanced Oil Recovery Laboratory, Geological Research Institute, No.6 Oil Production Plant, Daqing Oilfield, China

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Abstract

Tamtsag Oilfield is a low-permeability oilfield. In the actual production process, there will be “high water injection pressure and high injection difficulty”. In order to improve the waterflood development effect of low permeability reservoir, the selection of working fluid plays a key role. By measuring the interfacial tension between the working fluid and crude oil, combined with the depressurization and injection performance evaluation test, the anion-non-ionic surfactant working fluid system suitable for the characteristics of the Tamtsag reservoir was prepared. Under the condition that the formation water pH of oil formation in the Block 21 of Tamtsag oilfield is 7.5 and the salinity is 3000 mg/L, the injection increasing formula selected in this paper is: 0.9 % coconut oil diethanolamide+0.7 % sodium dodecylbenzene sulfonate+0.5 % anhydrous ethanol+3 % clay stabilizer. For cores with permeability lower than 80 mD, the depressurization rate can reach more than 25 %; For cores with permeability less than 15.9 mD, the depressurization rate can reach more than 30 %. The working fluid system can effectively improve the effect of increasing injection in Tamtsag Oilfield.