鄂尔多斯盆地永宁南长8致密油主控因素分析及有利区预测

Analysis of Main Control Factors and Prediction of Favorable Area for Chang 8 Tight Oil in South of Yongning,Ordos Basin

鄂尔多斯盆地永宁南长8油层组是延长油田致密油勘探的重点区域,对该区构造、烃源岩、储层、沉积相等进行分析,讨论致密油成藏主控因素并预测有利勘探区域。结果表明,西倾单斜背景上发育的低幅度构造对致密油成藏影响不大,但东西向展布的鼻状隆起可与砂体有机配置形成良好的岩性圈闭。巨厚的、优质的烃源岩是长8致密油成藏的基础。尽管致密油成藏对储层孔隙度、渗透率要求不高,但该区出油井储层孔隙度一般大于6.0%,渗透率一般大于0.1m D,表明物性对致密油成藏具有一定影响。水下分流河道中的厚层砂体是致密油富集的主要场所,也是研究区致密油成藏主控因素。根据成藏要素分析预测3个有利区,指导下一步勘探。

Chang8 oil reservoir in southern yongning is the main exploration area in yanchang oil field in Ordos Basin,in which the geological structure,source rocks,reservoirs,sedimentary facies have been analyzed,and discussed the main controlling factors for tight oil reservoir formation,as well as predicated the favorable exploration areas. The results showed that the low amplitude structure developed in western single slope has little effect on the tight oil accumulation,but the EW trending nose-upfit and sand body can form good lithologic trap by the organic configuration. The thick high-quality source rocks are the basis of chang8 tight oil reservoir formation. Though porosity and permeability have little effect on tight oil accumulation,but in this area the porosity and permeability higher than 6. 0% and 0. 1m D respectively,by which the tight oil accumulation should be affected. The thick sand in the subaqueous distributary channels is the main place of tight oil accumulation,and it is one of the main controlling factors. On this basis,three different favorable exploration areas have been predicted,and directed the exploration in the future.