川东北地区须家河组致密砂岩气藏异常高压成因  

Origins of Overpressure Tight Gas Reservoirs in the Xujiahe Formation,Northeastern Sichuan Basin

作　　者：李军[1] 邹华耀[1] 张国常[2] 李平平[1] 冯冲[1] 张彦振[1] 陈加松[1] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中国石油化工股份有限公司南方分公司勘探处,成都610041

出　　处：《吉林大学学报（地球科学版）》2012年第3期624-633,共10页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金重点项目(90914006)

摘　　要：对川东北地区各种超压潜在成因的系统分析结果表明,欠压实作用不是异常高压成因,现今异常高压主要由天然气的充注增压(充气作用)和中燕山—喜山期的强烈构造挤压形成。利用SRK实际气体状态方程对元坝、通南巴气田充气增压贡献进行了计算:元坝气田天然气的充注增压平均为25.21MPa,平均增压幅度60.86%;通南巴气田天然气的充注增压平均为45.81 MPa,平均增压幅度72.04%。其余主要为构造挤压增压,增压幅度在元坝、通南巴气田分别为39.14%和27.96%。中燕山—喜山期构造挤压活动强度的差异控制了应力释放区的分布和储层抬升降温降压的幅度,从而控制了现今压力场平面分布特征。通南巴地区由于晚期强烈的构造挤压活动,使其现今正处于应力充分释放的泄压区,充气增压、构造挤压之后降压过程的发生是其现今超压强度较低的主要原因。Systemic analysis on the potential causes of the overpressure in the northeastern Sichuan basin shows that the overpressures in tight gas reservoirs in Xujiahe Formation has been resulted mainly from the hydrocarbon accumulation and tectonic compression during the medium Yanshian to the Himalaya period, rather than compaction disequilibrium. By the SRK gas state equation, the pressure value of 25. 21 MPa is calculated in Yuanba gas reservoirs, which indicates that there is an average pressure amplitude of 60.86% and resulted from hydrocarbon accumulation. Meanwhile, the pressure value of 45.81 MPa is calculated in Tongnanba gas reservoirs, which has average pressure amplitude of 72.04%. The additional excess pressures have been generated mainly by tectonic compression, which account for 39.14% and 27.96%of the excess pressures in Yuanba gas reservoirs and Tongnanba gas reservoirs respectively. The difference of Yanshanian and Himalaya period controlled the tectonic compression intensity duri the distribution of present pressure, th ng the Medium e distribution of stress release area as well as the pressure- temperature reducing extent for tectonic uplift. TheTongnanba area is located in stress release area nowadays, and the pressure reducing process after hydrocarbon accumulation and tectonic compression is the major cause of the currently lower pressure than in the Yuanba area.

关 键 词：须家河组 欠压实作用 充气作用 构造挤压 致密砂岩 天然气 川东北 

分 类 号：P618.13[天文地球—矿床学]