深层页岩气断层属性对压裂缝网的影响

Influence of Fault Attributes of Deep Shale Gas on Fracturing Fracture Network

深层页岩地层断层较为发育,附近地应力场呈现非均匀分布,水力压裂产生的裂缝可能出现非平面、非对称、非规则延伸行为,进而影响压裂缝网体积。针对该问题,以川南区块Y101井区实际断层为例,构建了深层页岩气复杂构造内断层附近非均匀应力场表征模型与压裂缝网扩展模型,分析了断层特征参数对地应力的影响,并定量研究了断层类型、断距、长度、高度、走向、倾角和距离对压裂缝网体积的影响。结果表明:断层的断距、长度和高度越大,地应力偏转角和地应力差越大,压裂缝网体积越小;断层的倾角和远离断层的距离越大,地应力偏转角和地应力差越小,压裂缝网体积越大;断层的走向越大,地应力偏转角越大,地应力差越小,压裂缝网体积越大。断层参数对缝网体积的影响程度由大到小依次为倾角、走向、断距、距离、高度、长度。该研究可为深层页岩复杂构造下的缝网压裂优化设计提供理论依据。

Deep shale formation faults are relatively developed,and the nearby geostress field presents non-uniform distribution.The fractures generated by hydraulic fracturing may propagate non-planarly,asymmetrically and irregularly,which further affects the volume of fracture network.To address this problem,taking the actual fault in Well Y101,South Sichuan Block as an example,a non-uniform stress field characterization model and a compression fracture network expansion model of the faults in the complex deep shale gas formation were established to analyze the influence of fault characteristic parameters on the ground stress,and to quantitatively study the influence of fault type,fault distance,length,height,strike,dip angle and distance on the fracture network volume.The results show that the larger the displacement,length and height of the fault,the greater the geostress deflection angle and geostress difference,and the smaller the volume of fracturing fracture network.The larger the dip angle of the fault and the distance away from the fault,the smaller the geostress deflection angle and geostress difference,and the bigger the volume of fracturing fracture network.The larger the strike of fault,the greater the geostress deflection angle,the smaller the geostress difference,and the bigger the volume of fracturing fracture network.The influence degree of the following fault parameters on the volume of fracture network is in descending order:dip angle,strike,fault displacement,distance,height and length.The study can provide a theoretical basis for the optimization design of fracturing fracture network under the complex structure of deep shale.