川西DY构造须家河组致密砂岩储层裂缝分布控制因素

Controlling factors of fracture distribution in tight sandstone reservoir of Xujiahe Formation in DY structure, western Sichuan

王志萍 秦启荣 王保全 柳智利

西南石油大学资源与环境学院;中海石油(中国)有限公司天津分公司渤海油田勘探开发研究院;

1.School of Resource&Environment Science, Southwest PetroleumUniversity, Chengdu 610500, China; 2.Research Institute of Bohai PetroleumExploration and Development, Tianjin Company, CNOOC, Tianjin 300452, China

川西DY构造须家河组致密砂岩储层发育4种类型裂缝:构造缝、成岩缝、异常高压缝以及诱导层理缝,其中以高角度的平面"X"剪切缝为主。该区裂缝的发育分布受构造应力、构造部位、岩性、岩层厚度以及流体压力等因素的控制。构造应力的方向和强度控制了全区裂缝的类型和裂缝产状,在北西向(NW)挤压应力的作用下形成了高角度的南北向(NS)和近东西向平面"X"剪切缝以及北东向低角度的剖面"X"型剪切缝。构造主曲率大的地方和靠近断层的地方裂缝发育;储集层岩石中刚性成分体积分数高的层段裂缝比塑性成分高的层段发育;高流体压力影响早期裂缝的形成。DY构造中断层是控制裂缝发育分布的主要因素。

There are tectonic fractures, diagenetic fractures, fractures related to overpressures and induced fractures in the tight sandstone reservoir of Xujiahe Formation in DY structure, western Sichuan. Among them, the high angle tectonic fractures are dominant. The development degree of these fractures is controlled by tectonic stresses, structural locations, lithology, rock layer thickness and fluid pressure. The direction and intensity of tectonic stress control the type and occurrence of fractures in the whole region. Under the condition of northwest compressive tectonic stress, the north-south and east-west high-angle plane "X" shear fractures and the north-east low-angle cross-section "X" shear fractures form. Fractures develop at the locations that the main curvature is big and is near faults. Fractures developed are much more in the rock layers with high stiffness components than that of with high plastic components. High fluid pressure affects the early formation of fractures. Faults are the main factors controlling<BR>fracture development and distribution in DY structure.