Experimental Evaluation and Quantitative Characterization of “six Characteristics” of Unconventional Reservoirs—Taking Well Y of Shallow Lacustrine Facies in Northern Songliao Basin As an Example

The quantitative evaluation and characterization of "six characteristics" of shale and tight sandstone reservoirs is an important basis for unconventional oil and gas exploration and development. Taking Y well, a key lacustrine facies exploration well in the northern shore of Songliao Basin as an example, the experimental analysis of lithology, hydrocarbon source lithology, physical properties and pore structure, oil content, brittleness, mechanical properties and "six properties" supporting samples was carried out to quantitatively evaluate and characterize the "six properties" relationship. The results show that 6 kinds of lithology are developed in the second and third member of Qingqing, with a thickness of 59.3 m and 64 layers, and the thickness of shale accounts for 90.2%. There are 7 kinds of lithology in the first section of Qingqing, with a thickness of 72.64 m and 93 layers, 93.9% of which are shale. The fourth member of Quan consists of 5 lithologies with a thickness of 20.45 m and a total of 38 layers, with mud shale accounting for 53.0%. The contents of quartz and clay minerals in Qingshankou Formation are the highest in Qing1st Member, and feldspar and carbonate in Qing2nd and 3rd member. The shale of Qingshankou Formation is a good source rock with organic matter type I ~ II1, while the shale of Quantou Formation is a non-differential source rock. Lithology and source lithology control the oil bearing characteristics, reservoir quality and engineering quality of shale oil in Qingshankou Formation and tight oil in Quantou Formation. The shale pore and fracture combination in Qingshankou Formation constitutes the main reservoir space and flow channel for shale oil accumulation on a large scale. The characteristics of physical properties and pore structure affect oiliness and reservoir quality, brittleness and mechanical properties affect engineering quality. According to the results of "six characteristics" evaluation and characterization, the optimal "sweet bed" fracturing test production of shale oil in the first member of the Qing formation has an oil production day of 6.72 t.