鄂尔多斯盆地甘泉-富县地区长8成藏主控因素分析

Main controlling factor of Chang 8 in Ganquan-Fuxian areas,Ordos Basin

鄂尔多斯盆地甘泉-富县地区致密油勘探取得了一定的进展,但是长8成藏研究程度依然较低,从长8致密油分布特征、烃源岩分布特征、砂体展布带和相控带、运移动力等方面,对鄂尔多斯盆地甘泉-富县地区长8致密油成藏主控因素进行了探讨。发现长8油层组具有“源控区、砂体展布带和相控带、源-储压力差控位”特点,即优质烃源岩的分布控制着致密油的成藏位置和规模;三角洲前缘水下分流河道复合砂体为有利相带,有利相带物性相对发育区为油藏聚集的“甜点”区。长7、长9优质烃源岩与长8段优质储层之间的源-储压力差为石油短距离运移提供了动力,控制了长8致密油的形成与富集。

The tight oil exploration in Ganquan-Fuxian areas,Ordos Basin has made important progress,but study on Chang 8 accumulation is still low.The present paper study the distribution characteristics of Chang 8 tight oil,source rocks,sand body distribution and facies-controlled zones,migration dynamics and so on,the main controlling factors of Chang 8 tight oil reservoir formation in Ganquan-Fuxian area of Ordos Basin are discussed.It is found that the Chang 8 oil formation has the characteristics of"source-controlled area,sand body distribution zone and facies-controlled zone,source-reservoir pressure difference control",source rocks controll the Chang 8 location and scale of hydrocarbon accumulation.The large area of the underwater distributary channel composite sand bodies in the delta front are the main accumulation sites of the Chang 8 tight oil,and the partial"dessert"under the wide tight reservoir background is conducive to oil enrichment.The source-reservoir pressure difference between the high quality source rocks of Chang 7 and Chang 9 and the high quality reservoir of Chang 8 provides the motive force for the short distance migration of oil and controls the formation and enrichment of Chang 8 tight oil.