Geothermal Resource Evaluation of the Middle Permian Qixia-Maokou Formation in the Central Sichuan Basin, China

In the exploration and development of petroliferous basins, there are a large number of geological, geophysical, and geochemical data. They comprehensively understand the geological structure and geothermal reservoirs and have unique advantages in developing and utilizing geothermal energy. As an important petroliferous basin in China, Sichuan Basin is also rich in hydrothermal geothermal resources. Based on collecting relevant data and summarizing previous oil and gas exploration results, it is determined that most of the geothermal gradients in the Central Sichuan Basin are above 24 °C/km and most of the terrestrial heat flow is above 60 mW/m², which is a relatively high-value anomaly area in Sichuan Basin. Considering that the geothermal reservoir temperature and buried depth are important factors for the economic benefits of geothermal development, the geothermal reservoir of Qixia-Maokou Formation in central Sichuan Basin with relatively shallow buried depth (3000 ~ 6000 m), relatively high geothermal reservoir temperature (65 ~ 155 °C) and relatively thick geothermal reservoir (280 ~ 380 m) is selected to evaluate the potential of geothermal resources. In the study, a three-dimensional geological model is established by using different strata thickness parameters. Combined with the current geothermal field and rock thermal physical parameters, the temperature distribution in the middle of the Qixia-Maokou Formation is calculated by using a one-dimensional steady-state heat conduction equation. Finally, the geothermal resource intensity and resource quantity of the Qixia-Maokou Formation are calculated by using the volume method. The results show that the geothermal reservoir temperature of the Qixia-Maokou Formation in central Sichuan is 65 ~ 155 °C, and the total geothermal resource is 3.01 × 10²¹ J, equivalent to 103.025 billion tons of standard coal. Exploitable geothermal resources 2.03 × 10²⁰ J, equivalent to 20.65 billion tons of standard coal. According to the characteristics of geothermal resources in the Central Sichuan Basin, it is proposed to give priority to the central and eastern parts of the study area to carry out comprehensive development and utilization of medium and low-temperature geothermal power generation, geothermal drying, geothermal agriculture, and geothermal cascade utilization demonstration projects, laying the foundation for the secondary utilization of abandoned oil and gas wells and geothermal development in oil fields in the future.