Accurately measuring the wetting angles, interfacial tension, and pore-throat radii of reservoir rocks under high temperature and pressure conditions or in ultra-tight reservoir environments remains challenging due to laboratory limitations and instrument constraints. These challenges complicate the determination of capillary pressure during hydrocarbon migration and accumulation. Given this, we calculate the wetting angles of the calcite, montmorillonite, quartz, and feldspar surfaces, as well as oil-water and gas-water interfacial tension, under relatively low temperature and pressure conditions using molecular dynamics simulation. After validating the high consistency between the simulation results and experimental data, we expand this method to high temperature and pressure conditions to simulate the corresponding variations in the above parameters. Furthermore, we calculate the pore-throat radii of reservoirs using the multiple linear regression method. Through systematic simulations based on the regional settings of the Junggar, Ordos, and Songliao basins, we obtain data on burial depth-varying wetting angles, interfacial tension, and pore-throat radii of sandstone, volcanic, and carbonate reservoirs under high-, medium-, and low-temperature geothermal fields in China. Accordingly, the quantitative relationships are established between these parameters and the temperature-pressure conditions of petroliferous basins. The simulation results indicate that the water wetting angles of calcite, montmorillonite, quartz, and feldspar decrease gradually with increasing temperature, suggesting enhanced hydrophilicity. In contrast, the water wetting angles of these minerals increase with pressure, leading to reduced hydrophilicity. Generally, in oil reservoirs, calcite tends to exhibit oil-wet behavior, montmorillonite shows neutrality to water-wet characteristics, while quartz and feldspar primarily display water-wet properties. The oil-water interfacial tension decreases gradually with rising temperature but increases progressively with pressure. In contrast, the gas-water interfacial tension decreases with rising temperature and declines further with increasing pressure. The pore throat radii of rocks show certain correlations with porosity and permeability, suggesting that reservoir physical properties play a significant role in fluid migration. The minerals exhibit significantly different wettability, interfacial tension, and pore-throat structures across varying geothermal fields. Their wetting angles trend downward with increasing geothermal gradient. Meanwhile, their interfacial tension also decreases gradually with increasing geothermal gradient, which reduces molecular interactions at oil-water or gas-water interfaces, thereby enhancing fluid mobility.

Kerogen types exert a decisive effect on the onset and capacity of hydrocarbon generation of source rocks. Lacustrine source rocks in the Liaohe Western Depression are characterized by thick deposition, high total organic carbon (TOC) content, various kerogen types, and a wide range of thermal maturity. Consequently, their hydrocarbon generation potential and resource estimation can be misinterpreted. In this study, geochemical tests, numerical analysis, hydrocarbon generation kinetics, and basin modeling were integrated to investigate the differential effects of kerogen types on the hydrocarbon generation potential of lacustrine source rocks. Optimized hydrocarbon generation and expulsion (HGE) models of different kerogen types were established quantitatively upon abundant Rock-Eval/TOC/vitrinite reflectance (R_o) datasets. Three sets of good–excellent source rocks deposited in the fourth (Es4), third (Es3), and first (Es1) members of Paleogene Shahejie Formation, are predominantly types Ⅰ–Ⅱ₁, Ⅱ₁–Ⅱ₂, and Ⅱ–Ⅲ, respectively. The activation energy of types Ⅰ–Ⅱ₂ kerogen is concentrated (180–230 kcal/mol), whereas that of type Ⅲ kerogen is widely distributed (150–280 kcal/mol). The original hydrocarbon generation potentials of types Ⅰ, Ⅱ₁, Ⅱ₂, and Ⅲ kerogens are 790, 510, 270, and 85 mg/g TOC, respectively. The R_o values of the hydrocarbon generation threshold for type Ⅰ–Ⅲ source rocks gradually increase from 0.42% to 0.74%, and R_o values of the hydrocarbon expulsion threshold increase from 0.49% to 0.87%. Types Ⅰ and Ⅱ₁ source rocks are characterized by earlier hydrocarbon generation, more rapid hydrocarbon expulsion, and narrower hydrocarbon generation windows than types Ⅱ₂ and Ⅲ source rocks. The kerogen types also affect the HGE history and resource potential. Three types (conventional, tight, and shale oil/gas) and three levels (realistic, expected, and prospective) of hydrocarbon resources of different members in the Liaohe Western Depression are evaluated. Findings suggest that the Es3 member has considerable conventional and unconventional hydrocarbon resources. This study can quantitatively characterize the hydrocarbon generation potential of source rocks with different kerogen types, and facilitate a quick and accurate assessment of hydrocarbon resources, providing strategies for future oil and gas exploration.