准噶尔盆地腹部侏罗系油气成藏要素及评价模型

Controlling elements and evaluation model of the jurassic hydrocarbon accumulation in central junggar basin

准噶尔盆地腹部油气勘探潜力大,但地质条件复杂,油气富集规律不清。为进一步拓展勘探有利区带和靶区,基于前人研究成果,针对圈源高度分离、深源浅聚、古生新储的成藏特点,以隐蔽油气藏理论和含油气系统分析方法为指导,通过对油气藏的解剖和成藏条件的系统研究,明确了侏罗系油气成藏的控藏要素。研究认为,该区油气藏的形成主要受断裂垂向输导能力、砂体的储集物性和非均质性3因素的耦合控制。因此,将油气运聚作为一个概率事件,建立基于砂体圈闭有效条件下的油气运聚评价模型,分别求取断裂垂向输导评价Kf和砂体充注评价Ks系数,其乘积P即为油气运聚发生的概率,其中砂体的非均质性主要利用可容纳空间增加速率A与沉积物供给速率S的比值定量描述,实现了区内控藏要素的定量化表征,优选出了有利区带和勘探靶区,取得了明显的应用效果。研究成果可为相似盆地或地区的勘探提供借鉴意义。

There is great exploration potential in the central Junggar basin,but the geological conditions are complex and the oil and gas enrichment rules are unclear.To further expand exploration favorable zone and target,guided by the oil and gas reservoir theory and the analysis method of oil and gas bearing system based on the previous research results,and the characteristics of highly isolated oil and gas source,shallow accumulation of deep source and new storage of ancient source,the controlling elements of Jurassic hydrocarbon accumulation were clarified through the systematic study of the anatomy and conditions of reservoir formation.It was considered that the formation of oil and gas reservoirs was mainly controlled by the coupling of three factors-vertical transport capacity of faults,reservoir properties and heterogeneity of sand bodies.Therefore,as a probability event,an evaluation model of hydrocarbon migration and accumulation based on the effective conditions of sand body trap was established,and the vertical transport capacity evaluation K f and sand filling evaluation K s coefficients were obtained respectively.The product P was the probability of hydrocarbon migration and accumulation,in which the heterogeneity of sand body was described quantitatively by the ratio of space increase rate A to supply rates of sediment S .It realized the quantitative characterization of reservoir controlling factors in the area and optimized favorable zones and exploration target area,and obtained obvious application results.It was also of great significance to the exploration of similar basins or regions.