蜀南地区上三叠统须家河组成岩相划分

THE DIVISION AND DISRTRIBUTION OF DIAGENETIC FACIES OF XUJIAHE FORMATION IN UPPER TRIASSIC,SOUTH SICHUAN

蜀南地区须家河组储层物性的好坏受成岩作用的控制,研究成岩相及其展布规律,能有效地预测有利储层发育带,为油气勘探提供地质依据。根据控制沉积物孔隙形成与演化的成岩作用,将蜀南地区须家河组储层划分为五种成岩相,即浅埋藏强压实相、浅-中埋藏钙质胶结相、中埋藏绿泥石胶结相、中-深埋藏硅质胶结相和深埋藏溶蚀-高岭石胶结相。各种成岩相的形成和分布与沉积物的原始组分密切相关。各成岩相之间储层物性差别大,它们的不同组合可形成成岩圈闭。在蜀南地区的中部(川中—川南过渡带)有形成成岩圈闭的条件,因而在该地区进行油气勘探应不局限于构造圈闭。

The reservoir physical property of Xujiahe formation in south Sichuan is controlled by diagenesis. Research on its diagenetic facies can effectively forecast favorable reservoir area and provide reliable geological bases for exploration. The reservoir of Xujiahe formation is divided into five diagenetic facies according to the major diagenesis which control the formation and development of pore, they are the tightly-compacingt facies in shallow burial environment, the Calcium cementation facies in shallow-middle burial environment, the Chlorite cementation facies in middle burial environment, the Silicon cementation facies in middle-deep burial environment and the dissolution-Kaolinite cementation facies in deep buried environment. The formation and distribution of these facies are strongly related to the original components of sediments. The reservoir property among these diagenetic facies has great difference, and the assemblage of different diagenetic facies can form dianenetic trap. Oil and gas exploration in the middle of South Sichuan(that is transitional belt of middle-south Sichuan)should be not only in structural trap but also in diagenetic trap, because in these sections there are conditions to form diagenetic trap.