达县-宣汉地区长兴组-飞仙关组礁滩相特征及其对储层的制约

通过对普光2井、普光6井和毛坝3井等钻井资料以及地震剖面的详细研究,可知长兴组—飞仙关组生物礁相在地震剖面上,形态为透镜状,具有透镜体、中强变振幅、杂乱影像特征。岩性为灰色障积海绵礁灰岩、灰色障积海绵礁白云岩、灰色骨架海绵礁灰岩、灰色骨架海绵礁白云岩等组成。滩相在地震剖面上表现为透镜体、中强变振幅、不连续影像特征,其岩性主要为浅灰色厚块状亮晶鲕粒白云岩、亮晶含砾鲕粒白云岩、亮晶含豆粒鲕粒白云岩、亮晶生屑白云岩及亮晶砂屑白云岩等。两者在空间上相伴生,沿着台地边缘分布,形成台地边缘礁滩相带,该相带控制了达县—宣汉地区储层的岩性、储集性及其空间分布。

Reef-bank features of Permian Changxing Formation and Triassic Feixianguan Formation in the Daxian-Xuanhan Area, Sichuan Province, South China and constraint for the reservoirs of natural gas

Detailed studies of the seismic section and some wells such as the Pnguang 2, the Puguang 6 and the Maoba 3, demonstrate that the reef facies of the Permian Changxing Formation and the Triassic Feixianguan Formation shows a lens pattern with medium-strong varied amplitudes and chaotic images in the seismic section. The reef facies consists of gray limestones and dolomites of both sponge reef and frame sponge reef. The bank facies of the Permian Changxing Formation and the Triassic Feixianguan Formation exhibits a lens pattern with medium-strong varied amplitudes and discontinuous images in the seismic section. The bank facies consists of several rocks types, i.e. light gray thick-bedded to massive sparry oolitic dolomite, the sparry graveloolitic dolomite, sparry pisolitic-colitic dolomite, sparry bioclastic dolomite and sparry dolarenite. Both the reef facies and the bank facies are developed together and are distributed along the platform margin, where a special reef-bank facies zone was formed. This facies zone controls the petrological features, the reservoir qualities and the spatial distribution of the reservoirs of natural gas in the Daxian-Xuanhan Area.