Distribution Characteristics of the Deep Geothermal Field in the Sichuan Basin and its Main Controlling Factors

Abstract

Geothermal energy and petroleum are two resources that coexist in sedimentary basins, and both of them are closely related to temperature. Based on the surface heat flow and the rock thermophysical properties, the deep geothermal field was calculated, then temperature distribution characteristics and the primary influencing factors on the geothermal state were discussed. The temperature distribution map of the Sichuan Basin for depths of 3,000–9,000 m presented the central and southern areas are characterized by relatively higher temperatures while the northwestern and northeastern areas are characterized by lower temperatures. Strata temperature in the central and southern areas exceeded 150°C as the burial depth reached 5,000 m. At the depth of 7,000 m, the temperatures in the central and southern areas were above 180°C, which is the threshold temperature for hot dry rock (HDR), while the temperatures in the northwestern and northeastern areas were below 160°C, which is close to the lower limit for oil crude oil cracking. The central and southern areas are favorite zones for the exploration of geothermal energy, conversely, the relatively lower temperatures in the northern, northwestern, and eastern areas are conducive to the presence of oil and gas. The unevenly distribution of geothermal field were controlled by the thicknesses of sedimentary layer and the crust, which indicates the lithosphere flexure and thickening caused by compression and depression, rapid deposition in the foreland depressions. The results can provide geothermal understandings for the exploration and development of the petroleum and geothermal resources and could serve as a reference for geodynamic studies in the Sichuan Basin.

Thermal Lithospheric Thickness of the Sichuan Basin and its Geological Implications

“…Similarly, the good consistency between the thickness of the thermal lithosphere, the sedimentary thickness (Zhang et al, 2012), the surface heat flow (Xu et al, 2011b;Jiang et al, 2016;Zhu et al, 2018b), and the mantle heat flow (Fig. 6) (Qiu et al, 2022;Zhu et al, 2022) reflects the conductive lithospheric thermal structure in the Sichuan Basin, and indicates that flexural thickening of the lithosphere occurred in the eastern Sichuan fault-fold belt and the Longmenshan-Western Sichuan depression foreland basin system, while asthenospheric uplift occurred in the central Sichuan.…”

“…In the calculation process, the factors affecting the results mainly include the thermal conductivity, heat generation rate (A), stratigraphy of the crust, and terrestrial heat flow (q). The thermal conductivity (K), heat generation rate of the sedimentary layers and some basement rocks, and the terrestrial heat flow are mainly based on measurement results, which have been systematically summarized in previous studies (Xu et al, 2011b;Jiang et al, 2016;Zhu et al, 2018b;Tang et al, 2019;Qiu et al, 2022;Zhu et al, 2022). In addition to the measured heat flows (Table 1), interpolation values were also taken into the calculation (Fig.…”

Differential Thermal Regimes of the Tarim and Sichuan Basins in China: Implications for Hydrocarbon Generation and Conservation

“…5. Horizontal distribution pattern of the formation temperature at depths of 6,000 m, 7,000 m, 8,000 m and 9,000 m in the Sichuan Basin (Modified from Zhu et al, 2022).…”

“…2). The heat production rate and thermal conductivity of each stratum (layer) refers to the data of Liu et al (2016) and Zhu et al (2022). The thickness of each stratum (layer) was obtained from the drilling and/or seismic data.…”

“…9a). The horizontal distribution pattern of the present-day heat flow and deep formation temperatures in the Sichuan Basin is predominantly controlled by the basement relief (Xu et al, 2011;Zhu et al, 2022). Liu et al (2016) considered that the formation temperature distribution characteristics in the Tarim Basin with depths of 1,000-5,000 m were partially affected by basement relief.…”