柴达木盆地西部南翼山裂缝油气藏形成机制及分布规律

FORMATION MECHANISM AND DISTRIBUTION RULE OF NANYISHAN FRACTURED RESERVOIRS

通过对柴达木盆地西部南翼山裂缝油气藏的研究,并结合该区基本油气地质特征,认为该区裂缝类型主要为构造裂缝、成岩裂缝和孔隙流体异常压力裂缝;裂缝成因机制有所不同,各机制对本区裂缝的形成和发育程度影响也不同。构造作用是本区裂缝形成的主要动力,成岩作用对裂缝的生成及发育程度有一定的影响。孔隙流体异常压力仅对深部储层中裂缝的形成起到了促进作用;裂缝油气藏成藏组合均为自生自储,断裂带及其背斜轴部裂缝带控制了裂缝油气藏的总体分布。由于岩性及其组合对裂缝形成有一定的控制作用,导致纵向上裂缝性储层及油藏主要分布在碳酸盐岩较发育的层段和碳酸盐岩向膏岩过渡的层段。

Based on the analysis Of fractured reservoirs and petroleum geologic characteristics in Nanyishan Oilfield of Qaidam Basin, the paper concludes that the types of fractures can be identified as tectonic fracture, diagenetic fracture and abnormal pore fluid pressure fracture. Because the formation mechanisms of fractures are different, the developmental degrees of the controlled fractures are different, too. Tectonic action is the main force causing fractures in the area; diagenesis influences, in a way, the generation and developmental degrees of fractures. Abnormal pore fluid pressure only accelerates the formation of fractures in deep reservoirs. The hydrocarbon accumulating combination belongs to the self-generation and self-store mode. Fracture belts and anticlinal axis fracture belts control the distribution of fractured reservoirs. The fractured reservoirs distribute mostly in the effectively developed beds of dolostones and the transitional beds from dolostones to evaporates.