塔里木盆地克深2气田储层构造裂缝成因与演化

Genesis and evolution of reservoir structural fracture in Keshen-2 gas field, Tarim Basin

在储层构造裂缝力学成因分类的基础上,对克深2气田的构造裂缝进行成因分析,然后结合构造演化史和构造应力场演化史,研究克深2气田储层构造裂缝的演化特征,并分析构造裂缝形成期次与油气成藏的匹配关系。研究结果表明:克深2气田发育近EW走向、近NS走向和NW—SE走向的3组构造裂缝,其中近EW走向的构造裂缝主要受控于早期区域伸展作用、后期背斜弯曲拱张作用、异常流体高压作用、构造反转期应力转换作用以及逆冲断层伴生等因素,近NS走向的构造裂缝主要受控于近南北向的构造挤压作用,NW—SE走向的构造裂缝则主要形成于NNW—SSE或近南北方向的水平最大挤压应力;克深2气田发育白垩纪和古近纪末期、中新世末期、上新世末期3期构造裂缝,其中第2期和第3期构造裂缝是最重要的两期构造裂缝,与第2期和第3期成藏期具有较好的匹配关系,促进克深2工业规模气田的最终形成。

Based on the mechanical classification of reservoir structural fracture, the genesis of structural fracture in Keshen-2 gas field was analyzed, and the evolution characteristics of reservoir structural fracture were researched combined with tectonic evolution and tectonic stress field evolution. At last, the matching relationship between structural fracture forming periods and petroleum accumulation was analyzed. The research results show that Keshen-2 gas field develops 3 groups of struetural fracture, including approximately EW strike, approximately NS strike and NW-- SE strike The structural fractures of approximately EW strike are mainly controlled by early regional extension, late bending effect of anticline, abnormal high fluid pressure, stress converting effect in tectonic switching periods and associating effect of thrust fault, etc. The structural fractures of approximately NS strike are mainly controlled by tectonic compressive effect of approximately NS direction. And the structural fractures of NW--SE strike mainly generate from horizontal maximum compressive stress of NNW--SSE direction or approximately NS direction. Structural fractures in Keshen-2 gas field are mainly tbrmed in 3 periods： Cretaceous and Late Paleogene, Late Miocene, and Late Pliocene. The structural fractures tbrmed in 2＇la and 3rd periods are the most important to Keshen-2 gas field. These fractures in the two periods have a superior matching relationship with petroleum accumulation, which promotes the ultimate formation of industrial scale gas field in Keshen-2 area.