川西深层致密碎屑岩气藏储层预测方法

Prediction of gas reservoir in deeply buried tight clastic rock in west Sichuan.

川西深层须家河组致密碎屑岩气藏属近源气藏,具有超深、超压、超致密、低孔隙度、低渗透率和强非均质性的特点,其有利储层分布、储层裂缝发育带预测和含气性识别是制约气藏勘探开发的难点。为此,针对须家河组气藏的特点,基于储层特征分析及储层分类,建立了波阻抗反演与拟声波测井约束波阻抗反演、地震相划分、地震属性分析、地震分频预测等多技术相结合的有利储层横向展布预测方法;采用地质、地震、测井等多学科联合研究的方法,系统地建立了多尺度裂缝发育带预测和裂缝综合评价技术系列;以叠前反演和叠前地震属性提取方法为主,建立了AVO岩石物性参数反演、AVD叠前反演油气预测、Proni吸收滤波、吸收梯度预测、双相介质理论含气性识别、多尺度频率和吸收分析等含气性预测和识别的技术系列。综合利用上述方法,对须家河组致密非均质裂缝性储层进行了有利储层识别、裂缝检测和含气性预测,取得了较好的效果,预测结果与钻井结果吻合。

The tight clastic rock gas reservoir in deeply buried Xujiahe formation in west Sichuan is a near-source gas reservoir and charac- terized by super deep,over-pressured,excessively tight,low porosi- ty,low permeability,and high heterogeneity.The key problems for the exploration and development of such gas reservoirs are the pre- diction of potential reservoir distribution,fracture development belt,and recognition of gas-bearing area.Aiming at the characteris- tics of gas reservoir of Xujiahe formation,based on the reservoir characteristics analysis and classification,combining wave imped- ance inversion and pseudo acoustic logging impedance inversion with seismic facies classification,seismic attributes analysis,seismic frequency division prediction technology,the favorite prediction method for reservoir horizontal distribution was established.Multi- discipline study (geology,seismic,and logging) was adopted to es- tablish prediction technology for multi-scale fracture development belt and synthetic evaluation technology for fractures.The pre- stack inversion and pre-stack seismic attribute extraction method were applied to develop a series of technologies for gas-bearing pre- diction and recognition,including AVO petro-physical parameters inversion,AVD pre-stack inversion,Proni absorption filtering,ab- sorption gradient prediction,two-phase medium theory analysis, multi-scale frequency and absorption analysis,etc.By synthetically using the above methods,potential reservoir identification,fracture detection,and gas-bearing prediction were carried out on the tight heterogeneity fractured reservoir of Xujiahe formation.Good results have been achieved,which coincides with the drilling results.