东濮凹陷三叠系砂岩油藏裂缝特征及主控因素

Fracture Characteristics and Main Control Factors of Triassic Sand Reservoir in Dongpu Sag

为探讨东濮凹陷三叠系砂岩油藏储层裂缝发育特征、裂缝成因机制及控制因素,采用野外露头剖面观测、岩心观察、样品分析测试、常规测井、成像测井、核磁测井、岩石力学实验等技术方法对文明寨地区三叠系砂岩储层裂缝进行了研究。结果表明:东濮凹陷三叠系砂岩储层主要发育NNE向、NE向和近EW向3组构造裂缝,裂缝走向近于平行或垂直主断层方向,裂缝沿构造高部位呈带状分布。裂缝以高角度-近直立(60°～90°)缝为主,低角度(30°～50°)缝次之,高、低角度裂缝相互交错构成裂缝网络系统。岩心分析及孔隙度测井计算结果表明,裂缝孔隙度为2.60%～3.20%。构造应力场是控制砂岩储层裂缝发育的外部因素;储层岩性、砂岩厚度、岩石力学性质等是控制砂岩储层裂缝发育的内在因素。

In order to analyze the fracture characteristics, the origin mechanism and the controlling factors of Triassic sand reservoir in Dongpu sag, the techniques of field outcrop section observation, core overview, sample analysis, conventional logging, imaging logging, NMR logging, and rock mechanics experiment, and so on, were applied to study the fractures of Triassic sand reservoir in Wenmingzhai area. The research showed that there were three kinds of structure fractures as NNE, NE and nearly EW. The fracture trend was nearly parallel or perpendicular to the main faults. Fractures following tectonic highs appeared like belt. There were mainly high angle fractures （60°- 90°）, then low angle ones （30°- 50°）. They were mutually interlaced and formed the fracture network systems. Core analysis and porosity logging showed that the fracture porosity was 2.60 %- 3.20%, and the tectonic stress field was the external factor which controlled fracture growth in reservoir, while the reservoir lithology, the sand reservoir thickness, the rock mechanics nature were the internal ones.