Spontaneous imbibition characteristics of shale oil reservoir under the influence of osmosis

Abstract The spontaneous imbibition (SI) process in shale oil reservoirs is not only influenced by capillary force, but also the osmotic pressure between fracturing fluid and formation water nanopores media. In this study, experimental methods are used to investigate mechanisms of osmosis SI, taking into account presence initial reservoirs. To effect osmosis, SI experiments were performed on fine-grained felsic Qikou sag Dagang oilfield. Low-field NMR testers high-precision electronic balances utilized for measuring oil–water migration. results show that, when S w ≠ 0, high-salinity can be divided four stages: stage, drainage secondary stage stationary stage; = there no SI; 0 or low-salinity called “osmosis-enhanced SI”; we have found that “newly formed pores microfractures” as well reducing salinity promote SI. This article presents a systematic study under influence which provide useful information reservoir numerical simulation development program design.