准噶尔盆地玛湖凹陷百口泉组油气高产区控制因素与分布预测

Controlling Factors and Occurrence Prediction of High Oil-Gas Production Zones in Lower Triassic Baikouquan Formation of Mahu Sag in Junggar Basin

勘探理念的转变与认识的创新带来了勘探突破,在准噶尔盆地西北缘玛湖凹陷下三叠统百口泉组砂砾岩储集层中发现了国内外罕见的源外"连续型"轻质油藏,整装亿吨级油藏落实,展现出大油区的良好态势。玛湖凹陷百口泉组油气分布具有"整体含油、局部富集、甜点高产"的特点。油气高产受控于三大因素:发育扇三角洲前缘相规模有效储集层,且多见微裂缝;原油成熟度高、轻质、普遍含气;异常高压。扇三角洲前缘有利相带大部分位于异常高压与轻质油气重合区,预测油气高产有利区面积近2 800 km2,总资源量14.7×108t,是新疆油田油气储量与产量新基地,也是对全球"连续型"油气藏勘探与研究的重要补充。

The breakthrough of hydrocarbon exploration often depends on the change of explorative strategy and the innovation of exploration cognition,it is by which that a significant discovery in Junggar basin has been made recently.It is a continuous oil play in Baikouquan glutenite reservoir of the Lower Triassic in Mahu sag of northwestern margin of Junggar basin.In this play the integral a hundred-millionton oil reservoir with light-oil accumulation far from source sequences has been proven.The oil-gas distribution in this reservoir is characterized by integral oil bearing,local enrichment and ＂dessert＂ high production.The high production of hydrocarbon is dominantly controlled by three factors：（1） A large-sized and effective fan delta front facies reservoir with more micro-fractures; （2） high maturity of light crude oil and commonly producing gas,and （3） abnormal high pressure.This favorable facies belt is mostly distributed in the superimposed zones with abnormal high pressure and light hydrocarbons,showing the internal connection of hydrocarbon accumulation and enrichment.It is predicted that the area of future favorable exploration target could be about 2 800 km^2 and the total oil-gas resources amount to 14.7×10^8 t.It will not only be a new base for incremental hydrocarbon reserves and production of Xinjiang oilfield,but also an important supplement to global continuous oil play explorations and researches.