Pore and fracture characteristics of Cretaceous tight reservoir and its control effect on hydrocarbon accumulation in the Liuhe Basin  

作　　者：Wen-Hao Li Er-Qiang Yang Min Wang Yan-Ran Huang 

机构地区：[1]Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao,Shandong,266580,China [2]School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong,266580,China [3]Hunan Provincial Key Laboratory of Shale Gas Resource Utilization,Hunan University of Science and Technology,Xiangtan,Hunan,411201,China

出　　处：《Petroleum Science》2022年第5期1939-1949,共11页石油科学（英文版）

基　　金：founded by the National Natural Science Foundation of China(41922015)。

摘　　要：Tight oil and gas in the Cretaceous has been found in the Liuhe Basin,but the rules of tight reservoir and oil and gas accumulation are not clear.This paper discusses the developmental characteristics and evolution law of pores and fractures in the Cretaceous tight reservoir in the Liuhe Basin,and reveals its controlling effect on tight oil and gas accumulation.The results show that intercrystalline pores,intergranular pores and dissolution pores are scattered and only developed in shallow tight reservoirs,while microfractures are developed in both shallow and deep layers,which are the main type of reservoir space in the study area.The results of mercury intrusion porosimetry and nitrogen gas adsorption show that with the increase of depth,the proportion of macropores(microcracks)increases,while the proportion of micropores decreases.There are two stages of microfractures developed in the study area,corresponding to the initial fault depression stage from late Jurassic to early late Cretaceous and compressional uplift at the end of late Cretaceous.According to the principle of“inversion and back-stripping method”,combined with the data of optical microscopy and inclusions,the time of each key diagenesis and its contribution to porosity are revealed,and the porosity evolution history of reservoirs in different diagenetic stages is quantitatively restored.The porosity reduction rate of compaction can reach more than 80%,which is the main reason for reservoir densification.The relationship between pore evolution history and oil and gas accumulation history reveals that during the oil and gas filling period of the Xiahuapidianzi Formation(90-85 Ma),the reservoir porosity is only 1.15%,but the development of microfractures in the first stage of the reservoir is conducive to oil and gas accumulation.

关 键 词：Tight reservoir Microscopic pore structure MICROFRACTURE Porosity evolution Hydrocarbon accumulation the liuhe Basin 

分 类 号：TE311[石油与天然气工程—油气田开发工程]