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我国中西部前陆盆地天然气资源丰富 ,5个主要富气盆地的资源探明率只有 9.3 % ,天然气勘探潜力较大。中西部前陆盆地大中型气田有 7种富集成藏模式 ,其中冲断挤压作用是天然气分布的重要控制因素。研究分析了前陆盆地各二级构造带大中型气田类型及分布特点 ,认为冲断带下盘大型构造圈闭群、前渊斜坡岩性尖灭区带与浅层次生气藏、前缘隆起上的断块圈闭群等是前陆盆地有利的天然气富集区带。依据对前陆盆地地质规律深入研究的结果 ,结合目前天然气勘探实际 ,提出了大中型气田富集区带的优选原则 ,并优选了中西部前陆盆地 5个天然气富集区带 :塔里木盆地库车前陆冲断带中的克依构造带逆冲断裂下盘的膏盐层下部大型构造圈闭群 ,柴达木盆地北缘冲断带的冷湖—南八仙构造带 ,四川盆地川西北前陆凹陷前渊区带的盐井沟—苏马头—龙泉山侏罗系浅层气 ,川西前缘斜坡带的梓潼斜坡上三叠统须家河组岩性尖灭区带 ,准噶尔盆地南缘第二排、第三排构造带的第三系、白垩系气藏。图 1参 4(曾宪斌摘 )
The natural gas resources in the foreland basins in central and western China are abundant. The proven rate of resources in the five major gas-rich basins is only 9.3%, and the potential for natural gas exploration is relatively large. There are seven kinds of enrichment and accumulation patterns in the mid- and large-sized gas fields in the central and western foreland basins, of which thrusting and crushing are important controlling factors for the distribution of natural gas. The types and distribution characteristics of large and medium-sized gas fields in the secondary structural belts of the foreland basin are studied and analyzed. It is considered that the large structural traps in the lower thrust belts of the thrust belt, the lithologic pinch-out zone in the Qianwu slope and the shallow secondary gas reservoirs, On the block fault trap group is the foreland basin favorable natural gas enrichment zone. Based on the results of deep research on the geology of the foreland basin and the current exploration of natural gas, the principle of enrichment zone for large and medium gas fields is proposed, and five natural gas enrichment zones in the midwestern foreland basin are selected: Tarim Basin Large-scale structural traps in the lower part of the gypsum salt under the thrust belt of Ke Yi tectonic belt in the foreland thrust belt, the cold lake-Nanbaxian tectonic belt in the northern margin of the Qaidam basin, the northwest Sichuan Basin The Yanjinggou-Sumaitou-Longquanshan Jurassic shallow gas in the foredeep depression foredeep zone, the Triassic Xujiahe Formation lithotriptic zone on the Zitong slope in the western Sichuan front slope zone, the southern part of the Junggar Basin Margin of the second row, the third row of structural belt Tertiary, Cretaceous gas reservoir. Figure 1 Senate 4 (Zeng Xianbin pick)