致密砂岩与页岩压裂缝网形成能力对比评价

压裂裂缝网络形成的程度,是能否实现致密油藏经济有效的开采的首要因素。针对长庆油田长7致密砂岩油藏储层,采用了页岩用的裂缝网络形成的评价方法,结合声发射仪器,对比了长7致密砂岩与页岩2种岩心压裂后形成缝网的能力。通过实验可以看出,致密砂岩压后呈现为简单的平面主裂缝特征,而页岩均呈现无主裂缝的无规则散布特征;岩石脆性并不是影响致密砂岩形成缝网的主要因素;在无水平地应力差或水平地应力差较小的情况下,长7致密砂岩油藏储层能够形成一定程度的复杂裂缝;天然裂缝系统的发育程度也是长7致密砂岩油藏体积压裂形成缝网的关键因素。

Comparing evaluation of the ability of forming fracture network in tight sand reservoir and shale reservoir

The major factor that influences economical and effective exploitation of tight sand reservoir is the degree of generating fracture network. Aiming at the tight sand reservoir of Changqing oilfield, an evaluation method of ability of forming fracture network in shale reservoir has been used. Combined with acoustic emission instrument, the ability of generating fracture network in tight sand and shale has been compared. According to the result of evaluation experiments, the tight sand appears a feature which is simple planar major fracture. The shale appears a feature which is random distribution without major fracture. Rock brittleness is not the primary factor which influences fracture network for tight sand reservoir. In the condition of non- horizontal stress contrast or low- horizontal stress contrast, the tight sand reservoir could form sort of complex fractures. Development degree of natural fracture system is also a major factor which could influence formation of fracture network.