Microscopic occurrence and distribution of oil and water in situ shale:Evidence from nuclear magnetic resonance  

作　　者：Peng-Fei Zhang Shuang-Fang Lu Jun-Jie Wang Wen-Biao Li Ya-Jie Yin Guo-Hui Chen Neng-Wu Zhou Han Wu 

机构地区：[1]College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,266590,Shandong,China [2]Sanya Offshore Oil&Gas Research Institute,Northeast Petroleum University,Sanya,572025,Hainan,China

出　　处：《Petroleum Science》2024年第6期3675-3691,共17页石油科学(英文版)

基　　金：financially supported by the National Natural Science Foundation of China(42302160,42302170,42302183,and 42072174);the Sanya City Science and Technology Innovation Project(2022KJCX51);the Support Plan for Outstanding Youth Innovation Team in Shandong Higher Education Institutions(2022KJ060)。

摘　　要：Characterizing the microscopic occurrence and distribution of in-situ pore water and oil is crucial for resource estimation and development method selection of shale oil.In this paper,a series of nuclear magnetic resonance(NMR)experiments were conducted on shales from the Gulong Sag,Songliao Basin,China,at AR,WR-AR,WOR-AR,Dry,SO,and WR states.In-situ pore water and oil were reconstructed after WOR-AR.An improved T1-T2pattern for shale oil reservoirs comprising water and oil was proposed to classify and quantitatively detect pore fluids at different occurrence states.The total and free oil contents derived from NMR T1-T2spectra at AR states were found to correlate well with those from multistage Rock-Eval.Moreover,the NMR-calculated total and free oil are generally larger than those measured from multistage Rock-Eval,whereas adsorbed oil is the opposite,which implies that adsorbed,bound,and movable oils in shale pores can be accurately and quantitatively detected via NMR,without absorbed hydrocarbons in kerogen.As per the NMR T2and T1-T2spectra at WOR-AR state,the micro-distributions of in-situ pore water and oil were clearly demonstrated.Adsorbed,bound,and movable oils primarily occur in the micropores(<100 nm),mesopores(100-1000 nm),and macropores(>1000 nm),respectively,whereas capillary-bound water is primarily correlated with micropores.Thus,the microscopic occurrence and distribution of adsorbed oil are remarkably affected by pore water,followed by bound oil,and movable oil is hardly affected.This study would be helpful in further understanding the microscopic occurrence characteristics of pore fluids in-situ shale oil reservoirs.

关 键 词：POREWATER Pore oil Microscopic occurrence Shaleoil reservoir Nuclear magnetic resonance Gulong Sag 

分 类 号：TE34[石油与天然气工程—油气田开发工程]