Abstract:

The Yuejin slope area, which is located in the south of Yingxiongling sag and north of Zhahaquan sag, is the favorable directional zone of hydrocarbon migration, and has ample oil source. The comprehensive evaluation of source rock indicates that E²₃ source rocks in Zhahaquan sag are characterized by large thickness, widespread distribution, high abundance of organic matter, ideal type of organic matter, which are in mature stage now and has great hydrocarbon supplying ability. The research of oil-source correlation shows that the crude oil of Yuedong structure and Yuejin-1 structure has the same characteristics, their source is both from Yingxiongling sag in the north. The crude oil of Yuejin-2 structure, Wunan-Lücaotan and Kunbei oilfield is all from E²₃ source rocks in Zhahaquan sag, but the oil maturity is different. The maturity of crude oil from Yuejin-2 is low which is as same as that of crude oil from Wunan-Lücaotan and preserved solid bitumen from Kunbei oilfield, but is lower significantly than that of crude oil from Kunbei oilfield, the crude oil from Yuejin-2 is the early product of source rocks at low mature-mature stage, it has not been found product of source rocks at peak hydrocarbon-generating stage in Yuejin slope area. Yuejin slope area is closer to hydrocarbon generation center of sag than Kunbei oilfield, the product of source rocks at peak hydrocarbon-generating stage is characterized by priority infill injection, the lithologic trap and structure-lithologic trap widespreading in downdip direction of slope area have great exploration potential.

Key words: Qaidam basin, Yuejin slope area, Zhahaquan sag, oil source, exploration direction