摘要
在详细讨论声发射法地应力测定的理论前提的基础上,对川东北地区上三叠统-侏罗系致密砂岩进行了地应力测定和模拟地层条件下岩石力学性质的测试,根据地层条件下岩石的泊松比计算了该区历史构造应力,并进行了构造裂缝发育性的探讨.测试及计算结果表明:最大构造应力方向为NE向,值变化在21.4～34.5 MPa之间;地层条件下,沙一段和须六段平行层理样品的平均抗压强度高达546.6 MPa和410.5 MPa.自晚三叠世以来,对川东北地区影响强烈的构造运动可能主要有两期,分别是沙溪庙组沉积前和沉积后.构造应力值与地层条件下岩石的抗压强度相比似乎显得太小,因此储层裂缝的发育程度总体上较低.
One of the typical properties of Upper Triassic and Jurassic reservoir rocks in the northeast of Sichuan is compactification. So, the development of fractures in rocks is of great importance. Based on the detailed discussions on the feasibility and theoretical and experimental preconditions of geostress measurement by acoustic emission （AE）, the geostress compenents in rock samples from cores and outcrops were measured using the Kaiser effect of AE. The maximum natural horizontal compressive principal geostress ranges from 33.1 MPa to 49.8 MPa, with a strike ranging from 24.1° to 69.5°and the minimum from 17.8 MPa to 21.2 MPa. Combined with the tested Poisson＇s ratios of the reservoir rocks under the formation conditions, the authors estimated the tectonic paleostress, that is, 34.5 MPa for the maximum horizontal compressive tectonic paleostress for the Upper Triassic Xujiahe Formation, and Middle Jurassic Qianfoyan Formation, with a strike of 69.5°; and 26.6 MPa for the Middle Jurassic Shaximiao Formation, with an average strike of 24. 5°. Compared with the compressive strength of the reservoir rock samples parallel to bedding plane under the formation conditions （the average compressive strength is 410.5 MPa for the Xujiahe Formation and 546.6 MPa for the Shaximiao Formation）, the estimated tectonic paleostresses are too low to be able to produce fractures on a large scale in the Upper Triassic and Jurassic reservoir rocks as a whole.
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2005年第6期614-620,共7页
Journal of Chengdu University of Technology: Science & Technology Edition
关键词
声发射
KAISER效应
地层条件
构造应力
储层裂缝
acoustic emission
Kaiser effect, formation condition
tectonic stress, reservoir fracture
