通南巴构造石炭系分布预测

PREDICATION OF THE CARBONIFEROUS DISTRIBUTION IN TONGNANBA STRUCTURE

石炭系 (仅存黄龙组 )是川东、川东北乃至鄂西地区碳酸盐岩地层中最重要的一套储集层 ,但分布并不稳定 ,有些地区呈零星状分布甚至完全缺失。通南巴构造周边露头区二叠系直接与志留系不整合接触 ,未发现石炭系。但在地震剖面上 ,Tp1(二叠系底界 )反射之下、志留系弱反射之上有呈断续状分布的反射 ,并与零星分布的波阻抗大于 2 30× 10 5kg/m2 ·s高阻抗区域相对应。这些特征说明通南巴构造腹部存在石炭系。

The Carboniferous(only exists in Huanglong Formation)is the most important set of resevoir among carbonate rock strata in eastern and northeastern Sichuan and western Hubei.It is discovered that the distribution of the Carboniferous in unstable and present in some areas in scattered pattern or even completely absent.The Permian in surrounding outcrop areas of Tongnanba structure is in diredct unconformity contact with the Silurian where the Carboniferous can not be found.However,reflection distribution in the seismic cross section,below reflection of TP 1(bottom of the Permian )and above weaker reflection of the Silurian,appears to be in uncontinuously pattern and corresponds to higher impedance area of odd distribution of wave impedance>230×15(kg/m2·s,these features indicate that the Carboniferous exists in the center of Tongnanba structure.