Geological features of reservoir formation and exploration strategy of Xifeng Oilfield

Abstract

Xifeng Oilfield located in the southwest 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 a set 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.