The effective utilization of medium-high temperature geothermal energy is pivotal in reducing carbon emissions and plays a crucial role in developing clean energy technologies. The MiDu geothermal field, situated in the southeastern region of Dali Prefecture, Yunnan Province, lies within the Mediterranean–Himalayan high-temperature geothermal belt and is characterized by abundant geothermal resources. However, due to its considerable depth, exploration poses significant risks, resulting in a total utilization rate of less than 0.5% of the total reserves. This study employs natural seismic data to perform a tomographic analysis of the geothermal system in the Midu basin. By examining the P-wave velocity (Vp) and the velocity ratio of P-waves and S-waves (Vp/Vs) at various depths, the findings reveal that the basin comprises two distinct structural layers: the thrust basement of the Mesozoic and Paleozoic eras and the strike–slip extensional sedimentary layer of the Cenozoic era. A low-velocity anomaly in the central basin corresponds to the loose Cenozoic sedimentary layer. In contrast, high-velocity anomalies at the basin edges correlate with boundary faults and the Mesozoic–Paleozoic strata. Below a depth of 4 km, the Red River Fault and MiDu Fault continue to dominate the basin’s structure, whereas the influence of the Malipo Fault diminishes. The MiDu Fault exhibits higher thermal conductivity than the Yinjie Fault. It interfaces with multiple carbonate and basalt formations characterized by well-developed pores and fractures, making it a crucial conduit for water and a control point for geothermal storage. Consequently, the existence of medium-high temperature (>90 °C) geothermal resources for power generation should be concentrated around the Midu fault on the western side of the basin, while the Yinjie fault area is more favorable for advancements in heating and wellness.

The effective utilization of medium-high temperature geothermal energy is pivotal in reducing carbon emissions and plays a crucial role in developing clean energy technologies. The MiDu ge-othermal field, situated in the southeastern region of Dali Prefecture, Yunnan Province, lies within the Mediterranean-Himalayan high-temperature geothermal belt and is characterized by abundant geothermal resources. However, due to its considerable depth, exploration poses significant risks, resulting in a total utilization rate of less than 0.5% of the total reserves. This study employs natural seismic data to perform a tomographic analysis of the geothermal system in the Midu basin. By examining the P-wave velocity (Vp) and velocity ratio of P-wave and S-wave (Vp/Vs) at various depths, the findings reveal that the basin comprises two distinct structural layers: the thrust basement of the Mesozoic and Paleozoic eras and the strike-slip extensional sedimentary layer of the Cenozoic era. A low-velocity anomaly in the central basin corresponds to the loose Cenozoic sedimentary layer. In contrast, high-velocity anomalies at the basin edges correlate with boundary faults and the Mesozoic-Paleozoic strata. Below a depth of 4 km, the Red River Fault and MiDu Fault continue to dominate the basin's structure, whereas the influence of the Malipo Fault dimin-ishes. The MiDu Fault exhibits higher thermal conductivity than the Yinjie Fault. It interfaces with multiple carbonate and basalt formations characterized by well-developed pores and fractures, making it a crucial conduit for water and a control point for geothermal storage. Consequently, the existence of high temperature geothermal resources for power generation should be concentrated around the Midu fault on the western side of the basin, while the Yinjie fault area is more favorable for advancements in heating and wellness.

Production–reinjection spacing controls thermal interference and development cost, yet the economic consequence of imposing a reported long-term thermal screen is rarely quantified across multiple well clusters. This study analyzes 54 scenarios for six Guantao Formation clusters, nine reservoir-target spacings (100–900 m) and a 30-year horizon. An external project limit of no more than 1.5 °C production-temperature decline is considered before economic ranking. Reported extrema establish that every 100 and 200 m case fails. Conditional on the project report’s first-passing classifications, the thermal-screen candidates are 400 m for GR2 and GR4, and 500 m for GR3, GR5, GR6 and GR8; the archived cost-only minima are one 100 m grid interval smaller in every cluster. The archived study indicates a sub-percent cost increment for moving from the cost-only minimum to the reported thermal candidate in all six clusters, with a descriptive mean of approximately 0.4%. At GR6, 500 and 600 m differ by only 0.02 CNY GJ⁻¹ (approximately 0.06%), supporting a provisional 500–600 m decision envelope rather than a point optimum. In this setting, economically near-tied candidates are more appropriately represented as intervals than as unique point optima. These are conditional screening findings, not final well designs: the 54 machine-readable endpoints, complete operating inputs, executable model and economic workbook are unavailable, and several archived temperature trajectories cannot be reconciled visually with the reported 1.5 °C classifications. The analysis provides a multi-cluster estimate of the archived cost increment associated with the reported screen and shows how a near-tied alternative can be represented without claiming a unique optimum.

Thermal interference among neighboring piles can substantially alter the performance of energy pile groups, and its influence on heat transfer and deformation depends on pile position, spacing, layout, and ground properties. This study developed a three-dimensional thermo-mechanical numerical model to investigate these effects for energy pile groups equipped with U-type, W-type, and 3U-type heat exchangers. The thermal response was validated against a field thermal performance test, with a relative deviation of about 10%, and the mechanical component was additionally assessed against measured pile stress data from an independent single-pile test. Simulations over 700 h under summer heat rejection conditions showed that thermal interference intensified as the temperature fields of adjacent piles expanded and overlapped. Central piles experienced stronger interference than edge piles, and the resulting increase in outlet temperature was most pronounced for the 3U-type group. Increasing pile spacing reduced thermal field overlap and pile head displacement, although the additional benefit became limited beyond about 4–5 m within the 700 h simulation; this range is not a general design threshold. Differences between the investigated nine-pile square system and eight-pile staggered system were smaller than those associated with pile spacing. Because the two systems contained different numbers of piles, these differences are interpreted as system-level responses rather than isolated layout effects. For the central pile of the 3U-type group, increasing soil thermal conductivity, specific heat capacity, and density generally improved heat rejection and reduced the predicted pile head displacement within the investigated parameter ranges, with specific heat capacity producing the largest absolute variation in outlet water temperature under the investigated 700 h summer heat rejection conditions. These results indicate that energy pile group performance is governed by the combined effects of spatial configuration and ground thermal properties and cannot be inferred from isolated pile behavior alone.