Abstract:

Based on outcrop observation, drilling core description, physical properties and organic geochemical analysis, this paper studied the shale reservoir characteristics of Da’anzhai segment in Fuling area. The results show that high quality shale reservoirs of Da’anzhai segment are mainly developed in the semi-deep lake-deep lake phase, and the shale rock types include shale, silty shale, （inclusive） bioclastic shale and calcareous shale. Primary pores in shale reservoir disappeared after the diagenesis of compaction, cementation and solution, but the tectonic deformation and fracturing in late Yanshan-Himalayan formed a certain number of cracks. The dissolved pores and holes developed along fractures in the late diagenetic stage constitute important reservoir space and seepage channel space of shale reservoirs, and greatly improved the reservoir properties. The shale reservoir in the study area belongs to typical ultralow porosity and low permeability fractured reservoirs. The reservoir distribution is mainly controlled by sedimentary facies and fracture extent. The thick shale rich in organic matter in semi-deep lake-deep lake phase is favorable reservoir for shale gas resources.

Key words: flow units, reservoir architecture, remaining oil, Triassic, block-1 of Tahe Oilfield