复杂断块油藏建库圈闭密封性综合评价技术

Comprehensive evaluation technology of trap sealing performance in complex fault block reservoir construction

以M储气库为例,通过室内实验与理论分析,从盖层和断层综合评价圈闭密封性。从宏观、微观和力学评价盖层密封强度,从侧向、垂向和动态评价断层密封能力,落实圈闭密封极限压力。研究结果表明:盖层岩性以泥岩为主,厚度大,岩石致密、孔喉细小、排替压力大,岩石力学性质优良。主控断层两盘砂泥对接为主,断层泥岩比率(SGR)均较高,断层开启系数低,断层断面正压力大于7.5 MPa,断层岩排替压力大于储层岩排替压力,示踪剂等动态资料证实断层两侧不连通。综合评价M储气库圈闭密封性良好。由圈闭气体散逸、盖层毛细管密封失效、拉张和剪切破坏及断层剪切滑移失稳条件下盖层和断层的承压极限,综合确定圈闭密封上限压力为44.6 MPa。形成的复杂断块油藏圈闭密封性综合评价技术对同类油藏的密封性评价具有一定推广意义。

Taking M Gas storage as an example,indoor tests and theoretical analysis are used to thoroughly assess the trap sealing performance from caprocks and faults.The fault sealing capacity is evaluated from the lateral,vertical,and dynamic views,the sealing strength of the caprock is evaluated from the macroscopic,microscopic,and mechanical perspectives,and the ultimate pressure of the trap seal is calculated.The results show that mudstone comprises the majority of the caprock's lithology and that it possesses excellent mechanical capabilities as well as a large thickness,compact physical characteristics,narrow pore throat,and high displacement pressure.Sand and mud are primarily used to connect the two sides of the primary control fault,which also has a greater SGR and a lower opening coefficient.The two sides of the fault are not connected because the positive pressure of the fault section is larger than 7.5 MPa,the displacement pressure of the fault rock is greater than that of the reservoir rock,and this is proved by dynamic data such as tracers,etc.A comprehensive analysis indicates that M Gas storage has effective trap sealing.The upper limit pressure of the trap seal is determined to be 44.6 MPa based on the pressure limit of the caprock and fault under the conditions of trap gas escape,capillary seal failure,tensile and shear failure,and fault shear slip instability.A certain promotion relevance exists for the comprehensive sealing assessment technology of complex fault-block reservoirs formed in the sealing evaluation of related oil reservoirs.