地面微地震监测技术在南川页岩气田储层改造中的应用

Application of surface microseismic monitoring technology in reservoir reconstruction of Nanchuan shale gas field

南川页岩气田已进入全面开发阶段,通过微地震监测准确描述页岩气水平井水力压裂裂缝的展布规律、储层改造体积、裂缝复杂性等为后续压裂施工优化和加密井部署提供依据。鉴于南川区块采用地面布设检波器排列对A平台两口水平井66段压裂段进行地面微地震监测。根据监测结果描述每段压裂施工的裂缝发育过程,分析66段压裂后裂缝的分布特征:主要以人工裂缝为主,平均缝长290m、宽59m、高57m,井筒两翼改造范围近似对称,缝高以向上改造为主;储层改造总体积1.127×10^(8)m^(3),其中有效裂缝体积(DFN_SRV)4.82×10^(7)m^(3),占比近1/2;主裂缝方向为90°,与平台最大主应力方向基本一致;建立单段缝网复杂度评价模板,整体主缝形态突出,次生缝发育明显,缝网较为复杂。综合研究认为,A平台压裂后储层改造效果好,地面微地震监测技术对南川页岩气井压裂评估适用性高。

Nanchuan shale gas field has entered the stage of comprehensive development.Microseismic monitoring can accurately describe the distribution law,reservoir volume and fracture complexity of hydraulic fracturing in horizontal shale gas Wells,providing a basis for subsequent fracturing operation optimization and infill well deployment.In view of the fact that the nanchuan block adopts geophone array to monitor the surface microseismic of 66 fracturing stages of two horizontal Wells on platform A.According to the monitoring results,the fracture development process of each fracturing operation was described,and the distribution characteristics of fractures after fracturing in section 66 were analyzed:artificial fractures were the main ones,with an average fracture length of 290m,width of 59m and height of 57m.The transformation range of two shafts was approximately symmetrical,and the fracture height was mainly upward.The total volume of reservoir reconstruction is 1.127×10^(8)m^(3),of which the effective fracture volume(DFN_SRV)is 4.82×10^(7)m^(3),accounting for nearly half.The main fracture direction is 90°,which is basically consistent with the maximum principal stress direction of the platform.The single segment fracture network complexity evaluation template was established.The overall main fracture morphology was prominent,the secondary fracture development was obvious,and the fracture network was relatively complex.Comprehensive research shows that the reservoir reconstruction effect after fracturing of platform A is good,and the surface microseismic monitoring technology has high applicability to fracturing evaluation of Nanchuan shale gas well.