Diagenetic system of carbonate reservoir in Huanglong Formation from East Sichuan to North Chongqing area

The diagenetic manner and evolution stage as well as the corresponding geologic products and geochemistry characteristics of REE,carbon,oxygen and strontium stable isotope of Huanglong Formation in the area of East Sichuan to North Chongqing were comprehensively studied.According to the hydrological system,four diagenetic systems in Huanglong Formation were divided into pore water,compaction brine,atmosphere water and temperature-pressure water.When the source and property of fluid flow and the interaction process between fluid and rock of each diagenetic system are different,the effects of them to the reservoir development are various.So,the diagenetic systems and manner of diagenesis closely related with the reservoir development mainly include the role of burial dolomitization of compaction brine at the early diagenetic stage,the karstification of atmospheric water at the ancient epigenenesis,the role of tectonic disruption at the middle to late re-buried diagenetic stage.According to the coupling and matching relations between diagenesis and reservoir system in time and space,there are four control factors and patterns for reservoirs.The particles shoal of sedimentary microfacies controlled the distribution of location regional of reservoir.The early stage of burial diagenesis dolomite was the basis for developing Huanglong Reservoir.The dissolution of atmospheric water in ancient epigenenesis expanded the distribution of reservoir and the scope of the development scale and improved the quality of reservoir.The tectonic disruption further improved the reservoir porosity and permeability.