| The Ordos Basin hosts various types of natural gas resources and is the second-largest gas-producing basin in China. In recent years, several major discoveries have been made in natural gas exploration in the basin. However, unclear geological understandings, uncertain resource potential, and undetermined favorable exploration targets in the "three new" fields, including deep coalbed methane, marine shale gas, and Taiyuan Formation carbonate gas, have severely restricted the progress of natural gas exploration. Based on a systematic review of natural gas exploration advances and new geological insights in the basin during the 14th Five-Year Plan period, natural gas resource evaluation of the basin was carried out for the first time under the framework of the national standard Classification for Oil and Gas Mineral Resources Reserves issued in 2020. The evaluation results show that the in-situ resources, undiscovered petroleum initially-in-place, and technically recoverable resources are 6.03×1012 m3, 4.15×1012 m3, and 1.95×1012 m3 for conventional gas, 13.61×1012 m3, 3.25×1012 m3, and 1.74×1012 m3 for tight sandstone gas, 19.52×1012 m3, 18.33×1012 m3, and 9.17×1012 m3 for coalbed methane, and 2.80×1012 m3, 2.80×1012 m3, and 0.43×1012 m3 for shale gas, respectively.Combined with the natural gas resource evaluation results and exploration practices of the basin, it is proposed that deep coalbed methane and tight sandstone gas in the Upper Paleozoic Carboniferous–Permian, as well as conventional gas in the Lower Paleozoic Ordovician, constitute the realistic exploration fields. Conventional gas in Carboniferous–Permian carbonate rocks and bauxite of the Upper Paleozoic, and marine shale gas of the Ordovician Wulalik Formation in the Lower Paleozoic are regarded as breakthrough exploration fields. Continental and marine-continental transitional shale gas in the Upper Paleozoic Carboniferous–Permian, conventional gas in the Cambrian and deeper strata, etc., serve as prospective exploration fields. This paper identifies the favorable zones for future exploration of various natural gas resources, and predicts the changing trend of natural gas production in the basin before 2035 under three scenarios. |