考虑地应力影响的裂缝型致密砂岩储层有效性测井评价方法

Logging evaluation method for effectiveness of fractured tight sandstone reservoirs considering influence of in⁃situ stress

塔里木盆地库车坳陷迪北气藏侏罗系致密砂岩储层埋藏深度大,裂缝普遍发育,在常规岩石物理参数相似的情况下单井产能差异大,储层有效性传统评价方法适用性差。为了提高勘探开发效率,从地应力角度出发,分析地应力对储层的控制作用,研究其与储层有效性的对应关系,利用测井曲线构建最小水平主应力相对值、应力集中系数、裂缝活动性参数和裂缝有效应力4个参数,建立储层有效性评价标准。将该方法用于单井储层有效性评价中,效果良好。结果表明:地应力和岩石的应力集中控制着基质储层的有效性,裂缝的力学特性控制了裂缝的有效性,同时也是气井产能的主控因素,泥岩裂缝能否贯穿泥岩沟通上下砂体是单井高产的关键。研究成果对类似储层有效性评价具有一定的指导意义。

Dibei Jurassic tight sandstone gas reservoirs in Kuqa Depression in Tarim Basin are deeply buried,with fractures widely developed.Single-well productivity varies much in condition of similar conventional petrophysical parameters,and traditional methods for reservoir effectiveness evaluation has poor applicability.In order to improve exploration and development efficiency,control effect of in-situ stress on reservoir is analyzed,and its correspond-ing relationship with reservoir effectiveness is studied.4 parameters including relative value of minimum horizontal principal stress,stress concentration coefficient,fracture activity parameter and fracture effective stress are con-structed using logging curves to establish reservoir effectiveness evaluation criteria.The method is applied in single-well reservoir effectiveness evaluation,achieving good results.The results show that in-situ stress magnitude of and rock stress concentration control matrix reservoir effectiveness,and fractures mechanical property controls fractures effectiveness,which is also the main controlling factor for gas well productivity.Whether mudstone fractures can penetrate mudstone and connect upper and lower sand bodies is the key to high single-well productivity.The re-search has guiding significance for effectiveness evaluation of similar reservoirs.