Geothermal and Helium Resource Prospects in the Ordos Basin: Insight from the Curie Point Depths

The Ordos basin is a polycyclic superposition basin characterized by a diverse array of resources. The depth to the Curie point (CPD) serves as crucial evidence for investigating the crustal thermal structure and helium resource distribution within this basin. Through an analysis of magnetic anomaly characteristics in the Ordos basin, we calculated CPDs utilizing the power spectrum method with varying window sizes and moving steps, ultimately determining the average CPD as our final value. We analyzed CPD characteristics in conjunction with geothermal data and helium distribution. The CPD in the Ordos Basin ranges from 18 to 30 km, with an average depth of 23 km. This relatively minor variation in CPD suggests that the structural integrity of the Ordos Basin remains stable, indicating no significant thermal activity has transpired since its formation. A comparison with geothermal data from Changqing Oilfield reveals that variations in CPD align closely with observed geothermal features. Uplift areas associated with shallower CPDs include Yimeng uplift to the north, regions from Yinchuan to Jingbian on the western flank, and areas extending from Yichuan to Huanglong along the southeastern margin; these zones are presumed to possess enhanced geothermal resource potential. Notably, there exists a clear correlation between CPD values in the Ordos Basin and helium concentrations found within natural gas; higher helium content corresponds to shallower CPDs: a phenomenon likely attributable to radioactive decay processes involving uranium (U) and thorium (Th) present within source rocks throughout this basin. Based on these findings regarding CPD characteristics, in addition to Huanglong gas field, Dongsheng gas field, the west of Sulige gas field and the south of Sulige gas field, Qingyang-Huanxian-Huachi area and Zhidan-Jingbian area may also area may also represent prospective helium-rich zones within the Ordos Basin.