准噶尔盆地侏罗系页岩气地质特征及勘探潜力区识别

Geological characteristics of Jurassic shale gas and identification of potential exploration areas in Junggar Basin

通过开展露头调查、样品分析、老井岩芯观察、复查老资料以及参考有关准噶尔盆地油气最新的国内外公开文献等实物工作,对准噶尔盆地侏罗系烃源岩层段黑色泥页岩的沉积、烃源岩分布、厚度、地化、油气显示和含气性等主要页岩气地质条件进行梳理、评价,落实富有机质页岩发育特征及展布规律等生气物质基础。认为盆地具备前期实验性勘探开发条件的烃源岩赋存于侏罗系八道湾、三工河组和西山窑组,沉积相以湖相、半深湖、河流相和三角洲相为主,烃源岩沉积相为半深湖:八道湾组沉积层厚为200~800 m,富有机质泥岩面积为9×104 km^(2),厚度为50~320 m,平均厚度为112 m;三工河组沉积层厚为600~800 m,富有机质泥岩面积为9.1×104 km^(2),厚度为40~240 m。烃源岩TOC为0.37%~43.54%,R_(o)为0.45%~2.0%(低-成熟阶段),母质类型以Ⅱ_(2)-Ⅲ型为主,显示出以生气为主的特征;西山窑组生气物质基础相对较差。根据准噶尔盆地层沉积演化和常规油气研究成果印证,盆地侏罗系页岩地层主要为下侏罗统八道湾组、三工河组和中侏罗统西山窑组。根据侏罗系3层烃源岩的埋深、厚度、TOC和R_(o)等参数的分析和能源滚动开发、逐步深入以及最大规避风险的原则,盆1井西凹陷—中央坳陷—准南区域的侏罗系八道湾地层为先期探索性勘探潜力区范围。

Through outcrop investigation,sample analysis,old well core observation,review of old data,and reference to the latest domestic and foreign public documents on oil and gas in the Junggar Basin,et al,the black mud shale in the Jurassic source rock interval in the Junggar Basin has been developed.The main shale gas geological conditions such as deposition,source rock distribution,thickness,geochemistry,oil and gas display,and gas-bearing properties are sorted out and evaluated,and the gas material basis of organic-rich shale development characteristics and distribution rules are determined.It is believed that the source rocks with preliminary experimental exploration and develop ment conditions in the basin exist in the Jurassic Badaowan,Sangonghe Formation and Xishanyao Formation.The source rock sedimentary facies is semi-deep lake:the Badaowan Formation sedimentary layer is 200~800 m thick,the organic-rich mudstone area is 9×104 km^(2),the thickness is 50~320 m,and the average is 112 m;the Sangonghe Formation sedimentary layer is 600~800 m thick,and the organic-rich mudstone area is 9.1×104 km^(2),thickness is 40~240 m.The TOC of the source rock is 0.37%~43.54%,the R_(o) is 0.45%~2.00%(low-mature stage),and the parent material type is mainly typeⅡ_(2)-Ⅲ,showing the characteristics of gas mainly;The gas material basis of Xishanyao Formation relatively poor.According to the sedimentary evolution of the Junggar Basin and the research results of conventional oil and gas,the Jurassic shale strata in the basin are mainly the Lower Jurassic Badaowan Formation,Sangonghe Formation and Middle Jurassic Xishanyao Formation.According to the analysis of the burial depth,thickness,TOC content,R_(o) and other parameters of the three layers of Jurassic source rocks and the principles of energy rolling development,gradual deepening,and maximum risk avoidance,the Jurassic Badaowan stratum in the western sag of well Pen1-central depression south Junggar area is the scope of the early exploratory exploration potential area.