Petrology and Physical Characterization of Sandstone Reservoirs

The aim of this study is to investigate the petrological characteristics of the Jurassic Sangonghe Formation reservoirs in the Junggar Basin, Northwest China, and their physical characteristics in order to optimize the strategy of oil and gas exploration and development. Through the collection and analysis of core samples, this study systematically investigated the types, structural characteristics and pore-permeability relationships of the reservoir sandstones by using rock cast thin section analysis, pore structure delineation test by piezomercury method and experimental analysis by scanning electron microscopy. The results show that the sandstones in the reservoir of the Sangonghe Formation are dominated by feldspathic feldspathic sandstones and clastic feldspathic sandstones, and the maturity of the compositions is on the low side. The analysis of the rounding degree and cementation degree of the reservoir particles reveals its non-homogeneous characteristics, and the porosity and permeability show obvious positive correlation. Characterization of the pore structure of the reservoir shows that the size and distribution of the pore throat radius significantly affects the permeability, and the change of the throat has a more significant effect on the permeability. The porosity of the upper reservoir in the second section of the Sangonghe Formation ranges from 10.9% to 26.1%, with an average value of 17.6%, and the permeability ranges from 0.13 mD to 159 mD, with an average value of 24.43 mD. The characterization of the phase permeability analysis shows that the relative permeability of the oil phase decreases with the increase of the water saturation, and the relative permeability of the water phase increases, and the bound water saturation of the reservoirs in the study area is generally higher, with a range of 35.6% to 50.2%. 35.6% to 50.2%, with an average value of 41.6%, showing strong hydrophilicity. In summary, the petrological and physical characteristics of the Jurassic Sangonghe Formation reservoirs in the Junggar Basin are analyzed in detail in this study, which provides important geological data and theoretical basis for the exploration and development of oil and gas in this area.