油田开发过程中断层纵向封闭性解析方法及应用

Fault vertical sealing analysis method and application in oilfield development process

通过大量野外断层观察分析,认为断层结构主要由断层面和断层岩2个部分组成。断层纵向封堵能力主要受断层面的应力稳定性、断层岩孔隙结构封堵能力及断层岩破裂性的影响。利用便于生产调控的压力参数表征各影响因素,断层重开启压力表征断层面的应力稳定性,断层岩封堵压力表征断层岩孔隙结构的封堵能力,断层岩破裂压力表征断层岩的破裂性。根据地质力学理论推导了三维地应力条件下断层面重开启压力的解析方法,建立了考虑断层岩厚度的断层岩封堵压力解析方法,依据断层与注入井的距离,结合渗流理论得出了注入井井底流压的安全界限。对高89地区CO2驱油及封存实验区的注入井进行了安全性评价。

Through a large number of fault observation and analysis in the field,it can be concluded that fault structure is mainly composed of two parts:fault plane and fault rock.The fault vertical sealing ability is mainly affected by the stress stability of fault plane,the pore sealing ability of the fault rock and the rupture property of the fault rock.The above influencing factors are characterized by pressure parameters that are convenient for production control.The stress stability of the fault plane is characterized by the pressure of reopening of the fault,the pore sealing ability of the fault rock is characterized by the sealing pressure of the fault rock,and the rupture property of the fault rock is characterized by the fracture pressure of the fault rock.According to the geological mechanics theory,the analytical method of fault plane reopening pressure can be deduced under threedimensional stress condition.The analytical method for the fault rock sealing pressure can be established by considering the thickness of the fault rock.Combined with the percolation theory,the safety limit of the bottom flowing pressure of the injection well is obtained,which is based on the distance between the fault and the injection well.Finally,using the above methods,the safety of the injection wells in the CO2 flooding and the sealed experimentation area of the Gao 89 Region is analyzed.