四川盆地长兴期生物礁及礁型气藏

THE REERS OF CHANGXING PERIOD AND THE REEF GAS ACCUMULATION IN SICHUAN BASIN

长兴期是地质历史上四川盆地一次重要的成礁期，礁体星罗棋布，大小悬殊，形式多样。按礁上长的环境，长兴组生物礁可以分为三类：台缘礁、点礁和塔礁，分别形成于开阔海台地边缘、浅水台坪和较深水台洼区，发育期分别为长兴早期、中期和晚期。礁相以海绵为主要这架生物、以蓝绿藻和管壳藻等为粘结生物，附礁生物以苔藓、林皮和有孔虫为主。礁体在分布上多受断裂控制。由于成岩早期溶性和混合水白云岩化，孔隙度大为改善，具备独立形成储集体和成型气藏的成不条件，钻探成功率高，是目前四川盆地东部主要勘探目标之一。

Changxing Period was an impotant reef-forming one in the geological time in the Sichuan basin. The reefs were widespread in the Eastern Sichuan basin, with various scale, and forms. Based on the environments where they lived, the reefs can be divided into three types:shelf margin buildup, Patch buildup and pinacle, which were formed in the open sea platform margin, shallow water area and deep water depression on the Platform respectively. The sponge were the dominant reef building organism, which were cemented by cyanogpyton and aiphonate;twozoan, Echinoderm and Foraminiferan were subordinate orgnnnisms in reef facies. The distribution of the reefs was mostly controlled by the old fractures. As the karstification and minglewater dolomization in the earlier diagenetic, the porosity has been greatly improved. The reef body, with the possibility of forming independent reservoir and reef gas accumulation and high drilling succeeding(for gas) coefficient, is one important area of prospecting in the Eastern.Sichuan Basin recently.