Action mechanisms of abnormal fluid pressure on physical properties of deep reservoirs: A case study on Jurassic Toutunhe Formation in the southern margin of Junggar Basin, NW China  

作　　者：GAO Zhiyong CUI Jinggang FAN Xiaorong FENG Jiarui SHI Yuxin LUO Zhong 

机构地区：[1]PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China [2]College of Geosciences,China University of Petroleum(Beijing),Beijing 104900,China

出　　处：《Petroleum Exploration and Development》2023年第6期1398-1410,共13页石油勘探与开发（英文版）

基　　金：Supported by PetroChina Science and Technology Project(2021DJ0202).

摘　　要：Considering the action mechanisms of overpressure on physical changes in skeleton particles of deep reservoir rocks and the differences in physical changes of skeleton particles under overpressure and hydrostatic pressure, the sandstone of the Jurassic Toutunhe Formation in the southern margin of Junggar Basin was taken as an example for physical modeling experiment to analyze the action mechanisms of overpressure on the physical properties of deep reservoirs. (1) In the simulated ultra-deep layer with a burial depth of 6000-8000 m, the mechanical compaction under overpressure reduces the remaining primary pores by about a half that under hydrostatic pressure. Overpressure can effectively suppress the mechanical compaction to allow the preservation of intergranular primary pores. (2) The linear contact length ratio under overpressure is always smaller than the linear contact length ratio under hydrostatic pressure at the same depth. In deep reservoirs, the difference between the mechanical compaction degree under overpressure and hydrostatic pressure shows a decreasing trend, the effect of abnormally high pressure to resist the increase of effective stress is weakened, and the degree of mechanical compaction is gradually close to that under hydrostatic pressure. (3) The microfractures in skeleton particles of deep reservoirs under overpressure are thin and long, while the microfractures in skeleton particles of deep reservoirs under hydrostatic pressure are short and wide. This difference is attributed to the probable presence of tension fractures in the rocks containing abnormally high pressure fluid. (4) The microfractures in skeleton particles under overpressure were mainly formed later than that under hydrostatic pressure, and the development degree and length of microfractures both extend deeper. (5) The development stages of microfractures under overpressure are mainly controlled by the development stages of abnormally high pressure and the magnitude of effective stress acting on the skeleton particles. Mor

关 键 词：abnormally high fluid pressure deep reservoir MICROFRACTURE physical simulation of diagenesis Jurassic Toutunhe Formation southern margin of Junggar Basin 

分 类 号：TE31[石油与天然气工程—油气田开发工程] P618.13[天文地球—矿床学]