西峰油田成藏地质特征及勘探方向

西峰油田位于鄂尔多斯盆地西南部,是近两年来发现的一个亿吨级大油田.主力油层为三叠系上统延长组长8段,迄今共新增三级储量21956×10⁸t.鄂尔多斯盆地三叠系延长组主要发育一套内陆湖盆沉积的碎屑岩,厚度为500～1200m,自上而下可划分为10个油层段(长1至长10段).其中,以长6为重点的石油勘探在陕北地区取得了丰硕的成果,探明了安塞、靖安、吴旗、绥靖4个大油田.而西峰油田是盆地在长8油层段中发现的第一个亿吨级大油田.该区成藏地质条件优越,长7深湖相泥岩形成了丰富的油源,来自盆地西南方向物源所沉积的河流、三角洲砂体,提供了大面积储集体.在盆地区域平缓的构造背景下,发育了大型岩性圈闭,具有广阔的勘探前景.初步评价推测,长8在该区近期可形成(2～3)×10⁸t储量规模

Geological features of reservoir formation and exploration strategy of Xifeng Oilfield

Xifeng Oilfield located in thesouthwest of Ordos Basin was discovered in recent two years.The crude oil reserve in this oilfield is about 100 million tons.The major oil pay is Chang 8 of the Upper Triassic period in Yanchang Formation.Up to now,the newly raised total oil reserves including proven oil in place,controlled reserve and predicted reserve have reached 2.1956 billion tons.Yanchang Formation in the Triassic system of Ordos Basin developed aset of clastic rocks from 500 to 1200 meters in thickness,which was deposited by inland lake basin.Yanchang Formation can be divided into ten sections of oil formations.Chang 8 section is of the superior formation and reservoir conditions,and the deep lacustrine mudstone in Chang 7 provided the abundant oil resources.The fluvial and delta sandstone deposited from supply of the southwestern Ordos Basin provided a large area of reservoir.Large scale of lithological traps was developed at the background of regional gentle structure.It was preliminary estimated that Chang 8 section has the extensive prospects of exploration.In the near future，Chang 8 can form reserves scale of 0.2~0.3 billion tons.