川西地区深层雷口坡组微生物岩及其储层形成机理研究

The Leikoupo Formation microbialites and microbial carbonate reservoirs have been focused on in this research by the methodology of microbial sedimentology, reservoir geology and geochemistry. On microbial sedimentology, the microbial fabrics, microfacies, vertical development of the microbial carbonates and microbial constructions should be clarified. And then, the palaeocean, palaeoclimate and depositonal environments as well as the distribution of the microbial carbonates have to be in focus before the indication to the Anisian palaeogeography, palaeotectonic settings and collsion process of North China Plate with South China Plate being discussed. The mutual response among ‘microbialite’, palaeo-environmens and palaeotectonic settings would be considered. Meanwhile, the microbial carbonate reservoir diagenetic sequence, diagenetic fluids evolution as well as forming-keeping mechanism would be studied in reservoir gelogy work. Moreover, the comparision of microbialite and microbial carbonate reservoir would be made clear among the north, middle and south segments of Western Sichuan Basin. Finally, the Mesozoic microbial carbonte reservoirs of Western Sichuan Basin are going to be compared with the elsewhere in palaeotetyths region, with the global Anisian microbial sedimentary and reservoir-forming model being established.

本项目运用微生物岩沉积学、储层地质学和地球化学研究方法，对川西地区中三叠统雷口坡组（安尼阶）微生物岩和微生物岩储层进行研究，旨在查明微生物岩沉积组构类型、纵向发育特征、沉积微相与建造类型，恢复古海洋、古气候和古沉积环境，查清微生物岩的平面展布特征，探讨“微生物岩-古环境-古构造格局”响应关系；同时，明确微生物岩储层成岩序列与成岩流体演化特征，探讨微生物岩储层孔隙形成-保持机制，对比川西地区北段、中段和南段雷口坡组微生物岩和微生物岩储层的异同性，对比川西地区与古特提斯域其他地区的中生界微生物岩储层，建立全球中三叠世安尼期古特提斯域微生物岩沉积成储模式。

本项目运用微生物岩沉积学、储层地质学和地球化学研究方法，对川西地区中三叠统雷口坡组（安尼阶）微生物岩储层及其形成机理进行了研究。研究发现，明确了川西地区雷口坡组的地层划分对比标志，区域标准层“绿豆岩”稳定分布，识别出可识别的微生物类型有肾形菌（Renalcis）、葛万菌（Girvanella）、胶须藻属（Rivularia lissaviensis）、石囊藻属（Entophysalis）、曲线菌（Tortofimria）和空腔粘液菌（Gloeorrh）。微生物岩主要有叠层石、纹层石、凝块石、泡沫绵层石、枝状石和核形石。通过川西地区雷口坡组风暴岩的研究，确立了古海湾沉积格局，明确了其4期演化过程，为华北板块与扬子板块的拼合提供了佐证。通过川西地区北段、中段与南段微生物岩横向对比，发现川西地区雷口坡组潮坪微生物岩横向分布连续稳定，具有四段式结构，指出高温、高盐度和缺氧的古海湾背景、巨型季风干旱气候、外压内张的构造环境和水下古隆起局限下的古地理环境联合控制着微生物岩的发育和展布，同生-准同生期白云石化作用是微生物岩优质储层形成的关键，埋藏溶蚀作用促进了微生物碳酸盐岩储层的改善和保持。