川中地区须家河组岩性气藏特征与含气有利区预测——以安岳—磨溪地区须家河组二段为例

Lithologic gas reservoir characteristics and prediction of gas-bearing favorable zone of the Xujiahe Formation in central Sichuan Basin:Case study of the 2^(nd) member of Xujiahe Formation in Anyue-Moxi areas

为明确川中地区须家河组的气藏特征和富集主控因素,并有效地指导含气有利区预测,以安岳—磨溪地区须家河组二段为例,开展气藏特征和富集主控因素综合分析,针对性地采用一种有效的地球物理方法检测气层,进行含气有利区预测。研究认为:(1)安岳—磨溪地区须家河组二段主要为裂缝发育型岩性气藏,较发育低孔低渗的孔隙型或裂缝—孔隙型储层,具备有利的生储盖组合条件,平面上呈大面积、整体含气的分布特征;(2)气藏的富集高产主要受烃源岩条件、优质储层、局部构造和中、小断裂分布的影响,含气有利区受优质储层和中、小断裂分布的集中控制;(3)采用近道、远道反射特征对比与AVO主振幅主频率技术相结合的方法能有效地预测含气有利区分布,此方法可以在该类气藏的有利目标勘探中发挥显著作用。

To clarify the characteristics and main controlling factors of Xujiahe Formation gas reservoir in central Sichuan Basin,and to guide the prediction of favorable gas bearing areas effectively,this paper takes the 2^(nd) member of Xujiahe Formation in Anyue-Moxi areas as an example.Comprehensive analysis of the gas reservoir characteristics and main controlling factors of the Xujiahe Formation reservoirs have been carried out.An effective geophysical method is used to detect the gas reservoir and predict the gas-bearing favorable zone.The results show that:(1)The 2^(nd) member of Xujiahe Formation in Anyue-Moxi is mainly fracture developed lithologic gas reservoir,with relatively developed low porosity and low permeability pore type or fracture-pore type reservoir.It has favorable source-reservoir-cap combination conditions,and presents the distribution characteristics of large area and overall gas bearing on the plane.(2)The enrichment and high yield of gas reservoirs are mainly affected by source conditions,high-quality reservoirs,local structures and the fault distribution.Gas-bearing favorable areas are centrally controlled by the distribution of high-quality reservoirs and small and medium-sized faults.(3)The distribution of gas-bearing favorable zone can be effectively predicted by the combination of reflection characteristics comparison of near-far traces and dominant amplitude and dominant frequency technology.This method can play a great role for the favorable target exploration of this kind of gas reservoir.