Overpressure and gas charging in tight sandstone:Xujiahe Formation,northeastern Sichuan Basin  

作　　者：Jing-Dong Liu Cun-Jian Zhang You-Lu Jiang Guo-Shuai Bai 

机构地区：[1]Shandong Provincial Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao,Shandong,266580,China [2]Shandong Provincial Key Laboratory of Reservoir Geology,China University of Petroleum(East China),Qingdao,Shandong,266580,China [3]School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong,266580,China

出　　处：《Petroleum Science》2022年第6期2583-2600,共18页石油科学（英文版）

基　　金：financially supported by the Development Fund of Shandong Provincial Key Laboratory of Deep Oil and Gas,the Fundamental Research Funds for the Central Universities(20CX02110A);the National Natural Science Foundation of China(41702142)

摘　　要：Overpressure is a key factor for oil and gas charging in tight reservoirs,but it is still a challenge to evaluate the overpressure evolution and its control on oil and gas charging.Taking Xujiahe Formation in the northeastern Sichuan Basin as an example,this paper presented a method for evaluating overpressure and its effect on natural gas charging in tight sandstone in compressional basin.The abnormally high pressure and its causes were analyzed by measured data and logging evaluation.Theoretical calculation and PVT simulation were used to investigate the amounts of overpressure resulted from hydrocarbon generation and tecto nic compression,respectively.Then the source rock-reservoir pressu re differences were calculated and the characteristics of natural gas charging during the natural gas charging periods were analyzed.It was revealed that hydrocarbon generation and tectonic compression were the main causes of the overpressure.The overpressure of both source rocks and reservoir exhibited a gradually increasing trend from Middle Jurassic to Early Cretaceous(J2-K1),then decreased since Later Cretaceous(K2),and some of that preserved to now.The contributions of the hydrocarbon generation and tectonic compression to overpressure were different in different periods.The residual pressure difference between the source rocks and the reservoir is the major driving force for tight sandstone gas charging.The main hydrocarbon generating area of the source rocks and the area of high driving force were major natural gas enrichment areas,and the driving force determined the natural gas charging space in the pore throat system of the reservoir.This research helps evaluate the overpressure and pressure difference between source rocks and reservoir in compressed basin,as well as investigate the effective pore throat space of tight gas charging by the driver of overpressure.

关 键 词：Tight sandstone gas OVERPRESSURE Hydrocarbon generation Tectonic compression Driving force for tight gas charging Sichuan Basin 

分 类 号：TE37[石油与天然气工程—油气田开发工程]