牙形石色变在碳酸盐岩油气田勘探中的应用

The application of conodont CAI in carbonate oilgas fields exploration.

以四川盆地上二叠统为例，论述牙形石色变指标ＣＡＩ在碳酸盐岩油气田勘探中的应用。由２０余条实测剖面，获取了相应的ＣＡＩ值，据此划分了盆地上二叠统有机质热变质的成熟期，认为广元、北川、安县一带处于成熟期；川中、川南和川东等地区处于高成熟期；成都、南充、绵阳等地区处于过成熟期。根据ＣＡＩ值推算了盆地各地区的古地温，认为高值（１７０～４００℃）区在绵阳、成都、南充、达县及旺苍等地区；低值（５０～１００℃）区在广元至江油以北地区；川东、川南广大地区为１３０～２００℃。根据ＣＡＩ值及古地温，推算出上二叠统顶面埋藏深度，编制了埋深等值线图，与实测结果基本吻合。综合以上推算结果，预测四川盆地上二叠统的原油、凝析油主要分布在龙门山前缘带，其余地区主要产天然气。图３表５参６（梁大新摘）

At present, based on the organic particles and microfossils, such as sporepollen, vitrinite, kerogen, organic metamorphism in strata can be identified, and this method is effective to mudstone, clastic rocks, but not to carbonate rocks, conodont fossils are very common in the marine carbonate strata from Cambrian to Triassic. It means the organic metamorphism in marine carbonate rocks can be identified by using conodont color alteration. This method is effective, cheap and easily. Research results of years of the s are presented in the paper. It indicates that few common methods are useful for drawing CAI value contour maps which are significant to the carbonate oilgas fields exploration, for example, the conodont color alternation in carbonate strata for Upper Permian in Sichuan basin.