柴达木盆地狮子沟油田油气运移地球化学特征

Geochemical Charateristics of Petroleum Migration in the Shizigou Oilfield of Qaidam Basin

利用咔唑类化合物作为油气运移示踪剂,探讨柴达木盆地狮子沟油田的油气运移与运聚特征。生物标志物的组成显示狮子沟上第三系原油均具高伽马蜡烷含量和低姥鲛烷与植烷比值,暗示其单一盐湖相源岩特征。原油样品均检出丰富的咔唑类化合物,其总浓度在油区范围内呈现规律性的变化:从东南至西北依次降低;咔唑类运移参数也呈现相似的变化规律。这些规律性的变化预示了该油田原油的运移与聚集特征,这一特征也得到了原油成熟度规律性变化的佐证。

Carbazole and alkylcarbazoles were used as 'tracers' to investigate the migration of oil in the Shizigou Oilfield of Qaidam Basin.Biomarker compositions show that the oils from the Tertiary reservoirs have quite high abundance of gammacerane and low pristane/phytane ratios,indicates a unisource from a hypersaline lacustrine deposition of the oils.Carbazole and alkylcarbazoles are detected in high abundance for the oil samples.The total concentrations of carbazoles show a regular variation across the oilfield:decreasing progressively from the southeast to the northwest.Similar changes are also observed for carbazole-migration parameters.All the regular changes indicate that oils in the oilfield migrated from the southeast to the northwest and similar migration trend are also indicated by the regular maturity changes of the oils..