Constraint-First Thermoeconomic Assessment of Production–Reinjection Well Spacing in a Heterogeneous Guantao Sandstone Reservoir

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.