塔里木盆地含氦天然气差异性富集机理及有利富集条件OA

Helium,as a kind of globally scarce strategic resource,is primarily produced industrially through extraction from natural gas.However,the enrichment mechanism of helium in petroliferous basins remains poorly understood,which restricts the effective identification and development of potential industrial helium-producing areas.In this paper,the differential distribution patterns and formation mechanisms of the helium in the Tarim Basin are systematically elucidated by analyzing the geochemical conditions of natural gas and noble gas and dissecting the geological conditions of oil and gas reservoirs.Then,the factors controlling the differential helium enrichment in natural gas are discussed.Finally,a comprehensive helium enrichment model is established for the Tarim Basin,and the favorable enrichment conditions are identified.The following results are obtained.First,the helium-bearing natural gas reservoirs in the Tarim Basin are mainly He-hydrocarbon gas reservoirs,whose reservoirs are lithologically dominated by Paleozoic and Mesozoic carbonate and clastic rocks and burial depth is primarily great(4 500-6 000 m).Second,helium exhibits pronounced regional heterogeneity within the basin:the helium content is generally low in the Kuqa Depression,whereas helium is relatively enriched in the southwestern,northern,and central Tarim Basin.At the basin scale,helium is predominantly of crustal origin,with only minor mantle-derived helium input observed in the Akemomu gas field.In terms of gas source type,the helium content in oil type gas is generally higher than that in coal-derived gas.Third,the differential helium enrichment in the Tarim Basin is controlled by the coupling of multiple factors,including helium generation potential,fault-mediated migration pathways,transport carriers,and helium-bearing petroleum systems.At the microscale,a three-stage enrichment process is delineated:"radioactive decay supplying helium → subsurface water storage and transport →gas-water co-accumulation."At the macroscale,a composite accumulation model is established,characterized by"multi-type helium supply →segmented migration pathways → differential regulation."Fourth,the favorable conditions for helium enrichment in natural gas are proposed as follows:the synergistic coupling of regionally extensive and effective helium source rocks with discordogenic fault systems provides sufficient helium input;long-distance migration of natural gas promotes continuous helium enrichment;and an appropriate natural gas charging intensity prevents dilution of helium.In conclusion,the differential helium enrichment in the Tarim Basin is controlled by the spatial coupling relationships of helium generation,migration and accumulation within hydrocarbon accumulation units and the regional geological settings.The established dual-scale,micro-and macro-integrated enrichment model further advances the understanding of helium enrichment mechanisms in petroliferous basins and provides important guidance for the exploration deployment of helium resources and the prediction of high-quality helium-rich zones in the Tarim Basin.