214 / 2019-06-21 16:26:53

Analysis of shale reservoir characteristics and productivity control factors of Longmaxi Formation in Jiaoshiba area, Fuling

Fuling Jiaoshi Dam,Longmaxi Formation,shale gas,reservoir characteristics,controlling factors

Through the rock sample observation, thin section analysis and XRD test on the rocky samples of the Fuling Jiaoshi Dam and the Lower Silurian Longmaxi Formation in the neighboring area, the physical properties, reservoir space characteristics, geochemical parameters and Brittleness index were studied, It indicates that the sedimentary facies of the Longmaxi Formation in this area are deep-water continental shelf facies and shallow-water continental shelf facies, and the lower deep-water continental shelf facies is the main producing strata, The lithology is mainly gray-black with radiolarian carbonaceous shale, carbon-bearing silt shale, carbonaceous shale, and silt mudstone. The Longmaxi Formation shale is composed of clay minerals, quartz, carbonate, feldspar, pyrite and other minerals, while clay minerals are mainly illite. The total thickness of the shale is 70.1~86.6 meters, and the continuity is good in the longitudinal direction. The TOC ranged from 0.46~7.13% with an average of 2.66%, mainly due to the medium-to-high organic carbon content. The organic matter maturity in the lower part of Longmaxi Formation is in the stage of high evolution-over-evolution. Brittle minerals range from 33.9~80.3% with an average of 56.5%, mainly due to high brittle mineral content. The reservoir space is mainly composed of nano-sized organic pores and micropores among clay minerals, and intergranular pores and secondary dissolution pores are developed. The conventional physical property test has low porosity and low permeability. The porosity is 1.17~8.61%, with an average of 4.87%. The permeability distribution is between 0.1307×10-3~1.2674×10-3μm2, with an average of 0.4908×10-3μm2. The total gas content of the site is between 0.63~9.63 m3/t, with an average of 4.61 m3/t. According to the drilling capacity, the shale gas production control factors in this area include reservoir spatial structure characteristics and types, organic matter abundance and maturity, favorable sedimentary facies belt, organic-rich shale thickness, diagenesis, rock mechanics and structure. Function, top and bottom conditions.