| Based on the detailed analysis of the lithologic characteristics, sedimentary structure, sedimentary assemblage and facies sequence of field outcrops and drilling data, six types of sedimentary facies can be identified in Guanwushan Formation of Middle Devonian in Western Sichuan. From west to east, basin-slope facies, platform margin facies, open-confined platform facies, and tidal flat facies are developed successively. The distribution of sedimentary facies in northwest Sichuan is obviously controlled by Devonian syndepositional faults, with the characteristics of migration from west to east, and the evolution of platform margin from reef to shoal. Influenced by paleo-island, the distribution and evolution of sedimentary facies in southwest Sichuan is controlled by both syndepositional faults and barrier islands. Sedimentation controls the development of carbonate reservoirs of Guanwushan Formation obviously, which is mainly manifested in that sedimentation controls the type of carbonate reservoirs and the development degree of primary pores, the facies-controlled penecontemporaneous dissolution controlled by sedimentary cycles improves the primary pores, and facies distribution controlled by sedimentary evolution controls the plane distribution of carbonate reservoirs. |
