鄂尔多斯盆地上古生界煤系非常规天然气赋存特征

Deposition features of unconventional natural gas in Upper Paleozoic coal measures of Ordos Basin

基于天然气赋存特征与勘探开发存在密切关系,为了鄂尔多斯盆地非常规天然气高效开发提供理论支持,通过对U-1井上古生界沉积演化史、有机质热演化史、烃源岩条件、储层类型、储层物性条件及含气性综合分析的方法,探讨了U-1井含煤地层非常规天然气的赋存特征。结果表明,研究区上古生界含煤地层主要发育潮坪-三角洲沉积,盆地持续沉降形成气藏,源内、近源成藏组合构建垂向多套天然气成藏。研究区发育页岩-砂岩-页岩、页岩-煤-页岩和页岩-煤-砂岩-页岩三种赋存模式,其中页岩-煤-页岩模式总含气量较高,适合煤层气开采;页岩-煤-砂岩-页岩模式次之,适合煤层气、致密砂岩气和页岩气综合开采;页岩-煤-页岩模式适合致密砂岩气藏开采。

Based on the close relationship between the natural gas deposition features and the exploration development,in order to provide the theoretical support to the high efficient development of the unconventional natural gas in Ordos Basin,with the comprehensive analysis method of the Upper Paleozoic sedimentary evolution in Well U-1,the organic matter thermal evolution,hydrocarbon source rock condition,reservoir types,reservoir material condition and gas,the paper discussed the unconventional natural gas deposition features of the coal measures in Well U-1. The results showed that the Upper Paleozoic coal measure strata in the study area were mainly developed the tidal flat-delta sedimentary,the basin sustainable sedimentation formed the gas reservoir and the in source and near source formation combined structure formed the many vertical natural gas reservoirs. In the study area,three deposition modes of the shale-sandstone-shale,shale-coal-shale and shale-coal-sandstone-shale were developed. Among the three modes,the total gas content of the shale-coal-shale mode would be higher and would be suitable for the coal bed methane mining. The shale-coal-sandstone-shale mode would be second and would be suitable for the coal bed methane,compact sandstone gas and shale gas comprehensive mining. The shale-coal-shale mode would be suitable for the compact sandstone gas reservoir mining.