构造挤压在川东北地区飞仙关组异常高压中的作用

EFFECT OF TECTONIC COMPRESSION ON THE ABNORMAL PRESSURE OF THE FEIXIANGUAN FORMATION IN THE NORTHEAST SICHUAN

根据川东北飞仙关组地层压力分布与气藏的特征关系,研究飞仙关组异常高压形成的地质基础及构造挤压在异常高压中的作用。川东北飞仙关组鲕滩气藏原始地层压力在平面上分布极不均匀,高异常压力区呈局部块状分布。异常高压气藏多处于海槽区和台内致密灰岩分布区,储层以裂缝型为主,甲烷含量高、储层不含或者含极少量的沥青、硫化氢含量小、储层岩性以灰岩为主,储层连通范围小等特征。中三叠统雷口坡组及下三叠统嘉陵江组膏盐岩发育和封闭是高异常压力形成的地质基础,燕山晚期和喜山期的构造挤压则是飞仙关组异常高压形成的主要原因。

The effect of geological basis and structural compression on the abnormal pressure in the Feixianguan Formation is studied on the basis of relationship between the stratum pressure and the character of gas reservoir.The plan distribution of stratum pressure in the oolitic beach reservoirs in the northeast Sichuan is extremely uneven,characterized by partial distribution of abnormal high pressure.Abnormal high pressure gas reservoirs usually occur in the areas of sea trough or massive limestone.Gas reservoirs are composed mainly of fissure type with a poor connection scale,and have a dominant lithology of limestone.It is considered that the development and closure of gypsum layers in the Leikoupo Formation of Mid Triassic and the Jialinjiang Formation of Upper Triassic are the geological basis for the formation of high abnormal pressure,and the structural compression during the Late Yanshan Movement and Himalayan Movement is the major reason for the formation of abnormal high pressure.