窄河道致密砂岩气藏的断层有效性评价——以中江气田沙溪庙组为例

Evaluate the Effectiveness of Faults in Tight-narrow River Sandstone Gas Reservoir-taking Shaximiao Formation in Zhongjiang Gas Field as an Example

中江气田中上侏罗统沙溪庙组是致密砂岩气藏,评价其断层有效性对认识气藏内“断-砂”配置关系、油气充注度意义重大。通过三维地震构造解释方法获得断层的基本性质、断层内部结构、断面形态等,结合断裂构造演化评价断层的有效性。通过分析“断-砂-源”匹配样式及控气作用,研究断层与砂体的配置关系对气藏成藏的富集作用。研究表明,中江气田储层类型为低孔低渗的孔隙型,气藏为“深源浅聚、断砂输导”的“窄”河道致密砂岩次生气藏。通过分析现今“断-砂”配置关系,确定研究区内三类“断-砂”配置模式,并建立相应目标层级的评价标准。研究结果可以为中江气田沙溪庙组等此类窄河道致密砂岩气藏的断层有效性评价提供借鉴。

The dense sandstone gas reservoirs in the narrow channel of the Zhongjiang gas field are the sub-agrays of the“deep source shallow gathering”with faults as the migration channels.The effectiveness of the fault,that is,the“break-sand”configuration relationship directly affects the gas-filling degree of the gas reservoir.The three-dimensional seismic interpretation method of“well-seismic combination”was used to describe the basic characteristics of the fault,the internal structure of the fault,the shape of the section,etc.,which was combined with the results of the evolution of the fault structure to evaluate the effectiveness of the fault.By analyzing the“break-sand-source”matching pattern,the influence of the tectonic evolution of the fault and the configuration relationship with the sand body on the accumulation of gas reservoirs were studied.The result show that the Shaximiao Formation of the Jurassic in the Zhongjiang gas field is a“narrow”channel tight sandstone gas reservoir with deep-source shallow-collected and broken sand-conducting,and the gas reservoir is a low-porosity and low-permeability pore-type reservoir.By analyzing the configuration relationship between the accumulation period and the current“break-sand”,it is determined that the“break-sand”configuration mode is divided into three categories,and the corresponding target level evaluation criteria are established.The results provide an idea for the evaluation of the fault validity of the tight sandstone gas reservoirs of the narrow channel of the Shaximiao Formation gas reservoir in the Zhongjiang gas field.