准噶尔盆地侏罗系煤系地层致密砂岩气资源潜力分析

Analysis on the resource potential of tight sandstone gas of Jurassic coal measure in Junggar Basin,China

中国西部侏罗系煤系非常规致密砂岩气资源潜力巨大,正成为未来一大勘探领域。准噶尔盆地作为西部最大含煤盆地,广泛发育侏罗系煤系,致密砂岩气勘探前景良好。盆地腹部中下侏罗统煤系致密砂岩气气源岩为中下侏罗统八道湾组与西山窑组煤系烃源岩,形成自生自储成藏组合,具深盆气特征,主要分布于埋深4 500~6 000m深度范围。煤系烃源岩与砂岩储集层多呈"上下"或"三明治"组合形式,表现出典型致密砂岩气藏储集砂体致密、普遍异常高压、气水关系复杂、产能较低、准连续规模分布特点。初步估算盆地侏罗系煤系致密砂岩气地质资源量为(13 630~11 740)×108 m^3,技术可采资源量为(6 140~5 280)×108 m^3;腹部侏罗系煤系致密砂岩气资源潜力大,勘探前景良好;主要勘探方向为围绕中央凸起带的(莫索湾—白家海凸起)南北两翼与构造结合部,以及西部车排子凸起南部倾没端、东部北三台凸起西南倾没端;有利勘探目标区为莫索湾凸起南翼、白家海凸起南翼、莫索湾—莫北凸起结合部东侧、莫索湾—白家海凸起结合部、车排子凸起沙门子鼻隆及北三台西泉鼻隆,下侏罗统八道湾组应为主要勘探目的层。

The unconventional tight sandstone gas resources in the Jurassic coal measures in the west of Chi- na have great potential,becoming a major exploration area in the future.As the largest coal bearing basin, the Junggar Basin is rich in Jurassic coal measures. Thus, the tight sandstone gas with good exploration prospects should be an indisputable fact.The Lower-Middle Jurassic unconventional tight sandstone gas in the hinterland of Junggar Basin is derived from the source rocks of the Lower-Middle Jurassic Badaowan and Xishanyao Formations, forming a self generation and self-preservation assemblage with deep basin gas features.The burial depth is mainly 4 500-6 000m.The coal measure source rocks and sandstone reservoirsare characterized by combination types of ＂up and down＂ or ＂sandwich＂.The typical tight sandstone gas reservoir has characteristics of tight reservoir sand body,high pressure,complex gas and water relations, low productivity and quasi continuous distribution.According to a preliminary estimate, the gas geological resources of tight sandstone gas in the Jurassic coal measures are （13 630-11 740） ×10^8m3 ,and the techni- cal recoverable resources are （6 140-5 280）×10^8m3.The Jurassic coal measures tight sandstone gas in thehinterland of Junggar Basin has enormous potential and a promising prospect for exploration.The main ex ploration directions are the north and south wings and structural binding part of the central uplift belt （Mosuowan-Baijiahai Uplift）,the southern pitching end of Chepaizi Uplift in the west,and the southwest- ern pitching end of Santai uplift in the northeast.The favorable exploration target areas are the south-wing of Mosuowan uplift,the south-wing of Baijiahai Uplift, the east side of the structural binding part of Mo- suowan-Mobei uplift,the structural binding part of Muosuowan-Baijiahai Uplift, the Shamenzi nose uplift of Chepaizi Uplift,and the Xiauan nose uplift in the Beisantai area.The Lower Jurassic Badaowan Forma-tion should be the main exploration target.