川东五百梯气田成藏史的碳同位素分馏化学动力学分析

Study of natural gas accumulation history of Wubaiti gas field with chemical kinetics method of carbon isotope fractionation in Eastern Sichuan Basin

为探讨川东五百梯气田石炭系黄龙组气藏的成藏史,利用金管实验装置,在高压、恒速升温的条件下对四川盆地源岩抽提物样品进行了热解成气实验,结合气相色谱和碳同位素分析,得到了甲烷生成率、甲烷碳同位素与实验温度和升温速率的关系.由此建立并标定了油裂解成甲烷及其碳同位素分馏的化学动力学模型.所得模型在川东五百梯气田的初步应用显示,川东石炭系古油藏主要成气期集中在170～150Ma.天东1井、天东16井和天东2井对应气藏分别聚集了166,163,162Ma原油裂解生成的天然气,天然气损失率分别为16%,21%,32%.

In order to discuss the accumulation history of gas pool of Huanglong Formation of Carboniferous of Wubaiti gas field in east Sichuan Basin,by means of the gold tube thermal simulation equipments,source rock core extract samples from Sichuan Basin are carried out under high pressure and constant heating rate.Combining GC and carbon isotope analysis,the relationship between generation ratio of and carbon isotope ratio of methane and simulating temperature along with heating rate can be obtained.The initial application of the calibrated models in Wubaiti gas field in eastern Sichuan Basin suggests that Carboniferous paleo-reservoir cracked to gas mainly during 170～150 Ma.The gas pool of wells Tiandong 1,Tiandong 16 and Tiandong 2 accumulated respectively the natural gas since 166,163,162 Ma and the losing rate of gas was 16%,21% and 32% respectively.