四川盆地西部坳陷须家河组储层裂缝特征及分布评价

四川盆地西部坳陷须家河组砂岩储层是川西地区主要产气层段,该储层孔隙度、渗透率极低,裂缝是储层的主要渗滤通道,裂缝对储层含气性起重要作用,裂缝特征识别及分布在储层评价中较关键.通过岩心观察、测井资料分析,总结出该储层的裂缝主要为斜交裂缝,缝宽主要集中在0.5~2.0 mm,缝长主要集中在5~50 cm.研究认为该区主要有构造成因裂缝和区域性裂缝,并以丰谷构造为例,用变形应力场模拟法、构造主曲率法和构造滤波法评价了该区构造裂缝的分布,同时用厚度法和地质构造特征评价了区域裂缝的分布特征.

THE CHARACTERISTICS AND EVALUATION OF FRACTURES DISTRIBUTION IN XUJIAHE FORMATION IN THE WESTERN DEPRESSION OF THE SICHUAN BASIN

The sandstone reservoir of Xujiahe Formation in the Western Depression of the Sichuan Basin,is the main gas producing zone of the West Sichuan district.The porosities and permeability of the reservoirs are very poor.The fractures are the major filtration passages in the reservoirs and play an important role in gas containing capability of reservoir.So the feature recognition and distribution of fractures is critical to evaluation of re-servoirs.The author sums up the features of fractures through the analysis of rock core and well log information,and concludes that fractures in the reservoirs are mainly diagonal fractures.The width of fractures mainly is from 0.5 to 2.0 mm and the length of fractures mainly is from 5 to 50 cm.There are two main kinds of fractures in this areas: tectoclase and regional fractures.Taking Fenggu Structure as an example,the author makes the distribution evaluation of tectoclase by the means of distortional stress simulation,structure curvature and structure filtration and distribution evaluation of regional fractures,which has some guide contribution on exploration and exploitation in the areas.