塔里木盆地麦盖提地区石炭系油藏地球化学特征

Geochemical characteristics of the Carboniferous oil pools in Maigaiti area,the Tarim Basin

对塔里木盆地麦盖提地区石炭系油藏中油气地球化学特征及流体包裹体分析表明,天然气主要是高-过成熟的海相腐泥型气,巴什托地区天然气主要是高成熟的油田伴生气,和田河气田气则是过成熟的干酪根裂解气与原油裂解气的混合。巴什托地区原油主要是演化程度高的低硫、低蜡的轻质油;原油至少有两期充注,保存条件较好;油-源对比显示原油主要来源于寒武系,而与石炭系烃源岩无成因联系。巴什托油气藏主要有两大成藏期:一期是海西晚期,油气藏遭受一定程度的破坏;另一期是喜马拉雅期,以形成次生凝析油气为主。

Analyses of geochemical characteristics and fluid inclusions of the Carboniferous oil pools in the Maigaiti area in Tarim Basin reveal that the natural gas here is dominated by marine sapropel-type gas with high- over maturity. In the Bashituo area, associated gas with high maturity is predominant, while in the Hetianhe gas field, a mixture of over-mature kerogen-cracking gas and crude-cracking gas occurs. Crude oil in the Bashituo area is dominated by highly-mature light oil with low content of sulfur and wax. Oil charging occurs at least in two stages and the preservation conditions are good. Oil-source correlation shows that the crude oil mainly originated from the Cambrian and has no genetic relations with the Carboniferous source rocks. In the Bashituo area, hydrocarbon pooling occurred mainly in two periods： one is the Late Hercynian when the oil and gas pools were destructed to some degree ,and the other is the Himalayan when secondary condensate oil and gas were predominant.