准噶尔盆地北缘哈山构造带油气输导系统与运聚规律

Hydrocarbon Transmission System and Accumulation in Hala'alat Mountain Structural Belt in the Northern Margin of Junggar Basin

哈山构造带经历多期构造运动的叠加改造,造成地层的重复、缺失或倒转,地质结构复杂,油气成藏规律认识不清,制约了研究区的高效勘探。以已发现的油气藏和探井为研究对象,采用分单元解剖、地质与地化分析相结合的思路方法,运用有机地球化学手段追踪油气运移路径,明确了不同构造单元的油气输导配置样式,建立了4种油气运聚模式。研究结果认为:玛湖凹陷和哈山地区发育的风城组烃源岩在水体盐度、氧化—还原性等沉积环境指标方面存在差异。原油(油砂)生物标志化合物、含氮化合物等多参数运移路径示踪表明,浅层斜坡带与中深层推覆—冲断带的原油具有不同的油气来源,两者分属于不同的油气输导系统:斜坡带的原油来源于玛湖凹陷的风城组烃源岩,其生成的油气通过"断—毯"高效输导路径运聚成藏,具有远源供烃、横向输导的特点;推覆—冲断带的原油主要来源于哈山地区的风城组烃源岩,整体表现为烃源岩近源供烃、断层垂向输导的成藏特征,可进一步细分为3种运聚模式:推覆叠置区断裂、溶蚀孔缝发育,为"断—缝"复杂网络输导,冲断叠加区为"断层—砂体"阶梯状输导,褶皱变形区为断层优势输导—砂体辅助输导。上述研究成果对哈山构造带的油气勘探具有重要的指导意义。

The Hala＇alat Mountain structural belt is controlled by the multi-period structural superposition during the long geohistory,which caused stratum repetition,absence or reversion,the geological structure is complicated,and the rule of hydrocarbon accumulation is not clear,which restricts the efficient hydrocarbon exploration. Through typical reservoirs and wells dissecting,the geological structure of anatomy and the combination of organic geochemical analysis,based on the geological chromatographic effect principle of molecular compounds in crude oil in the process of migration,the study is performed in the characteristics of hydrocarbon transport in different tectonic units. The style of hydrocarbon migration in different tectonic units is cleared,and four models of hydrocarbon migration and accumulation are established. The geochemical fingerprint parameter characteristics of source rocks are contrasted and analyzed in detail,the sedimentary water salinity,oxidative indicators are different in Mahu Depression and the Hala ＇alat Mountain structural belt of the source rocks of Fengcheng Formation. Hydrocarbon migration is studied through geochemical tracing based on biomarker compounds and nitrogen compounds of crude oil（ oil sand）. The results showed that the shallow slop zone and the middle-deep nappe-thrust zone had different source rocks,and belonged to different hydrocarbon transporting systems. Through the ＂fault-carpet＂highly efficient transportation framework for hydrocarbon accumulation,the reservoir-formation characteristics of the slop zone which was mainly derived from the Fengcheng Formation source rocks in Mahu Depression generally showed distal lateral transportation and carpet-edge enrichment.The reservoir-formation characteristics of the nappe-thrust zone which was mainly derived from the Fengcheng Formation source rock in Hashan area generally showed proximal vertical and ＂multi-fault＂transportation. Furthermore,the style of ＂multi-fault＂model can be further subdivided into three types,which are fault micro-fracture net-shaped model in the western nappe superimposed region,the fault-sand ladder model in the middle thrust superimposed region,the fault dominant and sand body assisted model in the eastern faulted fold region. The results have important guidance for the exploration of hydrocarbon in Hala＇alat Mountain structural belt.