Injection of Low-Salinity Water as an Integral Part of Enhanced Oil Recovery Programmes for Carbonate Formations of the Central-Khoreiver Uplift Oilfields

The paper describes the process of evaluation of low salinity water composition to improve the development of hydrophobic carbonate formations of Central-Khoreiver Uplift (CKU) fields with relatively high oil viscosity (5-15 mPa·s) and average formation temperature 70°C. The sources of low salinity water were determined, prospective composition for water injection were analyzed. The efficiency of oil displacement by formation water and low salinity water are observed during the spontaneous imbibition experiments and coreflood tests to compare the efficiency of formation and low salinity water. The expected incremental displacement efficiency for the target carbonate formations can vary widely, from 1 to 10%. Linear models of the completed coreflood tests and a sector hydrodynamic model of the prospective trial injection are built, considering the basic chemical processes while mixing different types of water. We also review the prospects of joint application of low salinity water injection and chemical EOR methods.