柴西阿尔金山前中、下侏罗统展布及油气勘探方向

柴达木盆地西部阿尔金山前中、下侏罗统暗色含煤地层发育，对其沉积及展布特征认识不够是导致该区侏罗系油气勘探停滞不前的主要原因。以古水流分析为主要手段。结合地表露头、地层残留厚度及钻井资料对该区中、下侏罗统的展布特征及其对油气的控制作用进行了研究。结果表明，早、中侏罗世在古阿拉巴斯套山与古昆仑山之间发育一个大的近东西向展布的沉积坳陷（古泛茫崖坳陷）。坳陷的沉积中心在古阿尔金山区，西北部边界越过占阿尔金山区与塔东南中、下侏罗统沉积连为一体，东北部边界位于阿拉巴斯套地区，南部边界在红柳泉-煤沟-黑石山-月牙山一线。山前斜坡带分布多为冲积扇、沼泽化冲积平原等边缘相粗碎屑沉积，烃源岩不发育；而山前带清水沟-月牙山北一线湖相暗色泥页岩发育，为中等烃源岩，具备一定的生烃能力。该区油气勘探应以山前带为主，适当靠近阿尔金山的清水沟和月牙山西是两个有利勘探区。

Lower-middle Jurassic distribution and oil-gas exploration direction on the southern Altyn tagh in the western Qaidam Basin

A set of coal-bearing formation developed in the lower-middle Jurassic on the southern Altyn tagh in the western Qaidam Basin. Its sedimentation and distribution character was not well understood, which caused the oil-gas exploration in this area coming to a stop. Based on the data of Jurassic paleocurrents, outcrops, residual thickness and drilling sections, the lower-middle Jurassic distribution and its effect of controlling the oil-gas exploration direction were discussed. The resuits show a depression trending E-W developed between the old Alabasitao mountain and the Kunlun mountain with the depocenter in the old Altyn tagh region. The northwest edge of the depression crossed the Altyn tagh and conjoined with the southeast Tarim Basin. The northeast edge was ended in the Alabasitao region. And the south edge was restricted along the Hongliuquan-Meigou-Heishishan-Yueyashan. The present strata in the basin nearby the Altyn tagh are coarse elastic rocks deposited under alluvial fan and floodplains environment, where few source rocks are deposited. By contrast, the dark lacustrine mudstones on the southern Altyn tagh are moderate source rocks with hydrocarbon-generation potential. The direction of oil-gas exploration is mainly at the southern Altyn tagh. The areas of Qingshuigou and western Yueyashan are the best locations for oil-gas exploration.