Controlling factors of Dengying Formation reservoirs in the central Sichuan paleo-uplift

Macroscopic and microscopic characteristics revealed that the Dengying Formation reservoir in the central Sichuan paleo-uplift belonged to the compound genetic reservoir of the mound-shoal facies and karst. Development of the reservoir was controlled by the mound-shoal facies, and dissolution-enlarged or added pores (vugs) due to superimposed karstification modification were favorable reservoir spaces. The karst of the Dengying Formation in Tongwan stage was the stratabound-weathered crust karst of the early diagenesis stage, the extensive superimposition of mound-shoal facies and regional karstification in the central Sichuan paleo-uplift area was the key to develop the large-scale continuous Dengying Formation reservoirs. Due to differences in the development degree of mound-shoal facies and in the intensity of karst modification, the reservoir development degree varied in different zones in the paleo-uplift area. The NS-extending zone on the western side of the Gaoshiti-Moxi area was the sweet spot for reservoir development. Effective identification of mound-shoal facies and fine depiction of karst landform was the key for reservoir prediction of the Dengying Formation to discovery the superimposed area of the mound-shoal facies and the karst monadnock-karst steep slope which similar to Moxi-Gaoshiti area.