THE FEATURES AND EXPLORATION PROSPECT OF OUTCROP OIL ACCUMULATION IN QAIDAM BASIN

Outcrop oil accumulation is a special accumulation which is located in the wing of an outcrop anticline or in a monocline in the edge of a basin and is controlled by water table.It is a new explorating field.Through analyzing the geological conditions of oil accumulating and the exploration results in Yuqia oilfield in Qaidam basin,some viewpoints are put forward.Yuqia oilfiold in Qaidam basin is in an uncomplete outcrop anticline without trapping in top.The oil accumulation is lifted by underwater.It forms late and has good oil reservoir rocks with porosity over 17%.The oil in Yuqia oilfield is thin and the buried depth of oil accumulation is from 120 to 450 meters.Being of these features,it is considered as an outcrop oil accumulation.Qaidam basin is arid now.The depth of water table is from tens to hundreds meters in outcrop areas.It is abound in petroleum resources.There are many outcrop anticlines in the basin.The prospects for the exploration of outcrop oil accumulation in Qaidam basin is broad.