GEOLOGICAL CHARACTERISTICS OF WUFENG FORMATION AND LONGMAXI FORMATION IN BLOCK X OF CHANGNING SHALE GAS FIELD IN SOUTHERN SICHUAN CHINA

As a new clean natural gas energy, the exploration and development of shale gas resources has attracted worldwide attention. It is necessary to conduct in-depth study of the pilot demonstration area, analysis the geological characteristics of shale gas, and explore the main control factors in the process of accumulation. By taking the Block X of Changning shale gas field, Southern Sichuan, as the targeted area, we systematically evaluated the reservoir characteristics of Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation, based on the field outcrop sections, drilling coring and geophysical data. The results showed that the overall structure of the study area is well maintained, and the main production intervals of shale gas are located in the Wufeng Formation and Long-1 sub-member. Shale gas is mainly enriched in the middle and lower parts of Sq2. The content of brittle minerals (quartz + feldspar + calcite + dolomite) in shale gas production interval is high, with an average of 51.6%, and the fracturing ability is good. The reservoir space is dominated by inorganic pores, followed by organic pores, and the pore size is mostly between tens of nanometers and 200 nanometers. The physical property is good, and the average porosity is 4.58%.Overall, the physical properties of shale gas in Changning area are low porosity and low permeability.