Abstract:

The shale exploration potential of Wufeng-Longmaxi formation in Dingshan area of southeastern Sichuan is huge, and it is important to clarify the characteristics of shale reservoirs and their controlling factors. Through the “X” diffraction and Maps microscopic scanning of the whole rock, the shale mineral composition and microscopic pore structure were analyzed, and the shale mineral composition, reservoir space type, porosity, permeability and its controlling factors were studied. Then the sedimentary environment and tectonic movements was used to analyze reservoir development control factors. The results showed that the shale reservoirs in the Dingshan area were characterized by high organic matter and high brittle mineral content. The pore diameter development range was between 10 nm and 100 nm. The physical parameters such as porosity and permeability of different intervals were different. The porosity and permeability of the small layer 6~9 in lower part were high, and the permeability of cracks and phylogenetic development steeply increased. Reservoir development was affected by both sedimentary and tectonic movements. The sedimentary environment was the basis for the formation of shale reservoirs. Together with the burial evolution, the development of the primary reservoir space was determined. The later tectonic movements transformed the composition and structure of the reservoir space. On one hand, the micro fractures increased the reservoir space and seepage capacity, and on the other hand, the overdeveloped cracks destroyed the effectiveness of the reservoir.

Key words: Dingshan area, sedimentary environment, tectonic movement, Wufeng-Longmaxi formation, shale reservoir characteristics