摘要:天然裂缝发育特征及有效性是制约致密砂岩气藏有效勘探开发的瓶颈。以四川盆地元坝地区须家河组为例，运用野外露头、岩心、薄片、成像测井、实验分析以及生产动态等资料，对须家河组天然裂缝发育特征及有效性开展综合研究。结果表明：元坝地区须家河组天然裂缝比较发育，以构造剪切缝为主，裂缝有效性较好。按倾角划分，裂缝以高角度缝为主，多与岩层面垂直，主要走向为：NW-SE向、近E-W向、近S-N向以及NE-SW向；天然裂缝可划分为4期：Ⅰ成岩期；Ⅱ燕山构造运动中-晚期；Ⅲ喜马拉雅构造运动早-中期；Ⅳ喜马拉雅构造运动晚期；裂缝的有效性受控于裂缝的充填程度和开度、裂缝形成时期以及现今最大主应力等。结论认为，不同类型、不同产状裂缝有效性差异性明显，其中高角度缝、直立缝以及NW-SE向、近E-W向裂缝有效性最好，对致密砂岩气藏的开发具有重大意义。
关键词: 天然裂缝/
有效性/
裂缝发育特征/
致密砂岩/
须家河组/
元坝地区
Abstract:Natural fractures development characteristics and effectiveness restrict petroleum exploration and development of tight sandstone gas reservoirs. Taking Xujiahe Formation in Yuanba area of Sichuan Basin as an example, based on the field outcrop, core, thin slice, imaging logging, experimental analysis and production dynamics data, the characteristics and effectiveness of natural fractures are studied. Natural fractures of Xujiahe Formation are relatively well developed in Yuanba area, and structural shear fractures are the most developed ones, the fracture effectiveness is better. According to the dip angle, the fractures are mainly composed of high angle fractures that almost vertical to the strata, the main strike of the fractures is NW-SE, nearly E-W, nearly S-N and NE-SW. The formation period of natural fractures can be divided into four stages：Diagenetic period; the middle-late Yanshan tectonic movement; the early-middle Himalaya tectonic movement; the late Himalaya tectonic movement. The control factors of the fracture effectiveness are the filling and opening degree, fracture formation period and the maximum horizontal principal stress. There are obvious differences in the effectiveness of different types and different strike of the fractures, the effectiveness of high angle fractures, vertical fractures and NW-SE, nearly E-W fractures is the best, which is of great significance for the development of tight sandstone gas reservoirs.
Key words:Natural fractures/
Effectiveness/
Fracture development characteristics/
Tight sandstone/
Xujiahe Formation/
Yuanba area
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