Experimental study on water absorption characteristics of interbedded lithology in low permeability reservoir

In the development of low permeability reservoirs, long-term high pressure water injection leads to the formation of high conductivity water-injection induced fractures and the injection water into the non-reservoir lithologic section has also been found in the field inspection well sampling. However, the previous core evaluation is mainly based on reservoir lithology, and the water absorption characteristics of barrier and interlayer lithology and its influence on development effect were not clear. In view of the above problems, this paper takes Daqing Chaoyanggou oilfield as an example, studies the longitudinal lithologic distribution characteristics according to the field logging data and coring data, and statistics the main lithology in the non-reservoir lithologic section of Chaoyanggou oilfield. The water absorption characteristic experiment was carried out and the relevant reservoir parameters were clarified. Numerical simulation of reservoir considering interlayer water absorption is carried out by using Eclipse. The research results show that mudstone basically has no permeability, saturated water absorption coefficient increases with the increase of injection end pressure, and decreases with the increase of injection end to sample center distance. Silty mudstone has a certain permeability and water absorption characteristics between mudstone and argillaceous siltstone, and there is a phenomenon of fluid pressure transmission in the pores. The water absorption characteristic of argillaceous siltstone is consistent with the compression characteristics of fluid. The numerical simulation results of reservoirs with compartments are also more accurate, which explains the high injection-production ratio but low production in low permeability reservoirs. The results of this study have certain guiding significance for the efficient development of low permeability reservoirs.