Research on numerical simulation method of salt dissolution and recrystallization of inter-salt shale oil reservoir

Abstract

The Qianjiang inter-salt shale oil reservoir has a high content of salt minerals such as glauberite and halite. Salt dissolution and recrystallization will occur during the water injection development process, which will lead to changes in the porosity and permeability of the reservoir. At present, there is a lack of models and numerical simulation methods to characterize this phenomenon. Using theoretical derivation combined with laboratory experiments, programming and numerical simulation, a characterization model and reservoir numerical simulation method that can describe changes in reservoir porosity and permeability caused by salt dissolution and recrystallization have been established. Studies have shown that salt dissolution will increase the porosity and permeability of the reservoir, and the magnitude of the change is proportional to the amount of water passing, which can improve the flow ability of shale oil. To the contrary, recrystallization will cause the porosity and permeability of the reservoir to decrease, and therefore in the development process, salt crystallization inhibitors should be added to the injected water to avoid salt crystallization blocking the reservoirs around the well and wellbore and causing production decline or even shut-in.