巨厚砂砾岩储层X形水力裂缝的形成——以中国渤海湾盆地储层为例

Formation of X-shaped hydraulic fractures in deep thick glutenite reservoirs:A case study in Bohai Bay Basin,East China

中国渤海湾盆地致密砂砾岩储层广泛发育,它们通常为深埋巨厚储层,其有效开发需依赖水力压裂技术。为了研究砂砾岩储层水力裂缝的扩展特征,首先,探究了此地砂砾岩储层的地质条件,包括地层纵向分布规律和岩性特征;然后,通过地面微地震系统对该地区盐222区块几口井的压裂过程进行了监测。结果表明,目标井大多数地层压裂后均形成了X形水力裂缝。本文将储层形成X形水力裂缝的主要原因归于(1)储层非均质性和(2)两条近距离同向扩展的水力裂缝的应力阴影效应,并通过数值模拟等方法对其进行了详细分析和验证。本文的研究成果和结论可为巨厚砂砾岩储层水力裂缝扩展特征的深入研究提供参考依据。

Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs,the geological feature of reservoirs in Bohai Bay Basin is studied firstly,including the reservoir vertical distribution feature and the heterogeneous lithology.Then,hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system.Results show the hydraulic fractures generated in the reservoirs are mostly in X shape.The cause of X-shaped hydraulic fractures in this study is mainly ascribed to(I)the reservoir heterogeneity and(II)the stress shadow effect of two close hydraulic fractures propagating in the same orientation,which is confirmed by the following numerical simulation and related research in detail.This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs.