280 / 2019-07-29 22:43:18

Genesis of Grain beaches Reservoir in the Lower Cambrian Longwangmiao Formation in Central Sichuan Basin

Grain Beaches; Carbonate reservoir; Reservoir characteristics; Reservoir genesis, Central Sichuan basin

Combined with the relevant theories of sedimentology and carbonate reservoir geology, the characteristics and genesis of granular dolomite reservoir of Lower Cambrian Longwangmiao Formation in Moxi area, central Sichuan Basin are studied comprehensively with the data of core, thin sections and physical property analysis. It is found that the granular dolomite reservoir rocks of Longwangmiao Formation in Moxi area mainly consists of dolarenite, dolorudite and oolitic dolomite, and the reservoir space mainly consists of intergranular pores, intragranular pores and dissolved vugs. The pore-throat configuration is good, showing porous reservoir and pore-fracture reservoir. The development and evolution of granular dolomite reservoirs in Moxi area of central Sichuan basin, South China are controlled by both sedimentation and diagenesis: Influenced by the underwater paleo-uplift from Leshan to Longnusi in the sedimentary period, Moxi area of central Sichuan basin, South China mainly developed the "marginal shoal around the underwater paleo-uplift" and deposited a large set of thick-bedded granular carbonate rocks, which laid a good material foundation for the development of reservoirs. The dolomitization of medium salinity sea water and leaching of meteoric fresh water period improved the original pore structure in penecontemporaneous. With the impact of Caledonian supergene paleokarstification, a large number of bedding dissolved vugs were formed, and multi-stage burial dissolution adjusted and preserved the reservoir pore, forming a large number of dissolved vugs developed in the granular dolomite reservoir of Longwangmiao Formation nowadays.