Physical characteristics and controlling factors of tight sandstone gas reservoir: A case study of upper Palaeozoic tight sandstone in Shenmu Mizhi area

The Shenmu Mizhi area has multi-layered gas bearing formations, but the pore structure of the tight reservoirs in the area is complex. In this paper, first, the source characteristics of the reservoir in the study area were analyzed, and the reservoir petrological characteristics such as clastic characteristics, rock fragment characteristics, and reservoir filling material characteristics were explored. Second, the pore structure and throat characteristics of the study area were analyzed based on the genesis and distribution of pores, combined with morphology and structure. Third, the pore structure characteristics were elucidated, and the frequency distribution of porosity and permeability of typical rock cores were characterized. Results show the following: (a) The main types of pores are rock debris dissolution pores, followed by intergranular pores. The average facial recognition rate for a Qian 5 section is 2.42%. (b) Except for the Qian 5 section, the average mercury removal efficiency of all other layers is greater than 30%. (c) The porosity distribution range of the Qian 5 section of the Shiqianfeng Formation is 2.8% to 17.3%, with an average value of 8.5% and a main value range of >12%; The distribution range of permeability is 0.001-287.5 x 10(-3) mu m(2), with an average value of 3.31 x 10(-3) mu m(2) and a main value range of >1 x 10(-3) mu m(2).