Multi‐objective Optimization of Geothermal Extraction from the Enhanced Geothermal System in Qiabuqia Geothermal Field, Gonghe Basin

Abstract

A geothermal demonstration exploitation area will be established in the Enhanced Geothermal System of the Qiabuqia field, Gonghe Basin, Qinghai–Xizang Plateau in China. Selection of operational parameters for geothermal field extraction is thus of great significance to realize the best production performance. A novel integrated method of finite element and multi‐objective optimization has been employed to obtain the optimal scheme for thermal extraction from the Gonghe Basin. A thermal‐hydraulic‐mechanical coupling model (THM) is established to analyze the thermal performance. From this it has been found that there exists a contraction among different heat extraction indexes. Parametric study indicates that injection mass rate (Qin) is the most sensitive parameter to the heat extraction, followed by well spacing (WS) and injection temperature (Tin). The least sensitive parameter is production pressure (pout). The optimal combination of operational parameters acquired is such that (Tin, pout, Qin, WS) equals (72.72°C, 30.56 MPa, 18.32 kg/s, 327.82 m). Results indicate that the maximum electrical power is 1.41 MW for the optimal case over 20 years. The thermal break has been relieved and the pressure difference reduced by 8 MPa compared with the base case. The optimal case would extract 50% more energy than that of a previous case and the outcome will provide a remarkable reference for the construction of Gonghe project.

Fluid Chemical and Isotopic Signatures Insighting the Hydrothermal Control of the Wahongshan-Wenquan Fracture Zone (WWFZ), NE Tibetan Plateau

“…As atmospheric components may inadvertently mix into samples during gas collection procedures, Duchkov (2010) suggested adjusting the R-value of geothermal gas samples using the 4 He/ 20 Ne ratio to mitigate the impact of atmospheric contamination during sampling [53]. The atmospheric ratio of 4He/20Ne is approximately 0.318.…”

“…The atmospheric ratio of 4He/20Ne is approximately 0.318. Therefore, when the 4 He/ 20 Ne ratio of a sample closely approaches 0.318, it indicates that the helium in the sample is predominantly of atmospheric origin. The correction equation is as follows: In the equation, the subscripts c, m, and a correspond to the calibration value, test value, and characteristic value of the atmospheric source, respectively.…”

“…Sano (1982) suggested the presence of three helium sources in natural gases: atmospheric, mantle, and crustal [54]. They devised a formula to determine the mixing ratio of different helium sources in gas samples using the ratios of 3 He/ 4 He and 4 He/ 20 Ne, along with a graphical representation of the relationship between 3 He/ 4 He and 4 He/ 20 Ne. This method streamlines the process and enhances the clarity of helium source identification.…”

“…The helium content in samples H01 and H05 primarily originates from the α-decay of 238 U, 235 U, and 232 Th in the crust's natural radioactive systems, accounting for over 97% on average. A plot of the 3 He/ 4 He-4 He/ 20 Ne relationship of the geothermal gases in the study area is shown in Figure 6, and the He isotope R/Ra values (ratio relative to the atmosphere) of the hot-water gases in these two locations belong to the crustal helium domain (<0.05), indicating that they are predominantly crustal in origin. representation of the relationship between 3 He/ 4 He and 4 He/ 20 Ne.…”

“…Relevant studies have also focused on the north-south Himalayan rift zone [3][4][5], the Yunnan-Tibet geothermal zone [6,7], and several fault zones where hot springs in western Sichuan are relatively concentrated [8][9][10][11][12][13][14]. Only with the exploration of high-temperature hot dry rock resources Energies 2024, 17, 2715 2 of 17 in the Gonghe Basin on the northeastern margin of the Tibetan Plateau in recent years [15] has the region gained widespread attention, and a large number of studies have been carried out to address the mechanism of the heat source and the potential for development [16][17][18][19][20][21][22].…”