下寺湾油田延长组长8段致密油富集主控因素及“甜点”模式

Main controlling factors of enrichment and sweet spot mode of tight sandstone oil reservoir in Chang-8 Member of Yanchang Formation in Xiasiwan Oilfield

下寺湾油田在延长组长8段致密油的勘探中有了一定突破,但由于长8段致密油藏基础地质研究较为薄弱且成藏较为复杂,油气富集主控因素及“甜点”模式尚未明确,因此,在大部分区域其开发效率较低。为了进一步探明长8段致密砂岩油藏的勘探开发前景,在之前致密砂岩油成藏条件研究的基础上,利用岩心、测井、录井、分析化验等资料,结合试油、试采及水平井生产数据,对研究区长8段致密油成藏主控因素进行了深入分析。研究表明:“优质烃源岩”“优相优储”“较高的过剩压力差”和“广泛发育的微裂缝”是研究区长8段致密油藏成藏的四大主控因素。在此基础上建立了长8段致密油5种“甜点”模式,并根据5种不同的“甜点”模式,对其合理开发方式分别进行了分析,为长8段致密油藏的高效勘探开发指明了方向。

Some breakthroughs have been made in the exploration of tight sandstone oil reservoir in Chang-8 Member of Yanchang Formation in Xiasiwan Oilfield recently.However,as the basic geological study of Chang-8 Member is relatively weak and the hydrocarbon accumulation condition is complex,the main controlling factors of enrichment and the sweet spot mode have not been proved.Therefore,the development efficiency is low in most areas.In order to further explore the prospect of exploration and development for the tight sandstone oil reservoir in Chang-8 Member,based on the previous study,the main controlling factors of reservoir formation were analyzed deeply in the study area by the data of core,logging,mud logging,analysis and testing,and combined with the production data of oil testing,production testing and horizontal wells.The results show that the accumulation of the tight sandstone oil reservoir Chang-8 Member is mainly controlled by four main control factors:high quality source rocks,excellent reservoir properties under favorable sedimentary microfacies,higher excess pressure difference and widely developed micro-fractures.And on this basis,five sweet spot modes of Chang-8 Member tight oil could be established,and the reasonable development modes are analyzed respectively according to these five modes,which indicated the direction for the efficient exploration and development of the tight oil reservoir in Chang-8 Member.