Abstract:

The formation of Da'anzhai limestone reserviors are closely related to multi-stage deephydrothermal dissolution. Lake beach and lakeside factes are most favourable for the development of the dissolution;the fluid that exuded by argillaceous source rocks of semi-deep lacustrine factes during different evolution stage6 is the primary solution source;Late YenshanEarly Himalayan period is the main formation stage of the reservoirs due to frequent dissolution. The deep hydrothermal dissolution could be divided into diagenetic, tectonic and postdiagenetic stages and five secondary mineral filling substages. It is pointed out that the occurrences of the pores,caves and fractures, the cathodoluminescence of the filling minerals, thegeochemical properlies,the inclosions,lithologic and fluid characters of different stages differdifferently. Based on the above mentioned, a model of deep hydrothermal dissolution inDa,anzhai abnormal limestone reservoirs is proposed in this paper.