Rock-water interaction during the exploitation of oil pools in subsalt and intersalt rocks: The pripyat depression as an example

Subsalt and intersalt oil pools, which are exploited with the application of water injection technique, are characterized by the dissolution of catagenetic halite and sulfates in pores, cracks, and caverns inside productive rocks, the precipitation of neogenic minerals, and the decomposition of dolomites. These processes lead to a substantial change in the initial filtration and reservoir properties of the rocks. Methods, algorithms, and computer program, which are proposed to estimate scales of the lithohydrogeochemical processes, make it possible to control changes in productive rocks, along with their filtration and reservoir properties, during the flow of waters from the injection zone to the drainage zone. It has been demonstrated that the dissolution of halite fillings is the most essential process leading to a significant increase in the filtration and reservoir properties of rocks during the exploitation of flooded oil pools. Thus, during the whole period of exploitation of some pools in Belarussian oil fields, up to 1.2 million m³ of sodium chloride, which was previously present as halite cement, were extracted together with the associated water. It is concluded that the currently popular lithohydrogeochemical approach to the study of processes in water-saturated rocks systems can be successfully used for solving many problems related to not only natural geological processes but comparable (in scale) technogenic processes induced by water-rock interactions during the exploitation of oil pools.