大宛齐油田溶解气扩散特征及其扩散量的计算

通过对库车坳陷大宛齐油田第上系和上第三系康村组的油田溶解气组成在深度上的分布特征分析，认为大约在理深450m以内的上部油层溶解气扩散作用强烈，不仅致使甲烷含量降低，乙烷、丙烷等组分百分含量相对升高，而且也降低了气油比，扩大了油藏的地饱压差。根据Fick第二 扩散定律模拟计算油层的溶解气中甲烷,黉人上新世中期到第四纪末期，油田上部的散失比例为54％，埋藏深度较大的下部油层的扩散作用较弱，散失比例为13％。

Simulation of diffusion quantity of solution gas in Dawanqi oil field

After analyzing the component of solution gas at different depth in Dawanqi oil field, in this paper, the authors consider that the diffusion of solution gas is remarkable in upper-oil layer in depth less than 450 meters. The diffusion not only leads to methane percent content decrease, ethane and propane etc percent content increase, but also reduces gas-oil ratio and enlarges pressure gap between formation pressure and saturation pressure of oil reservoir. According to simulation by Pick second diffusion law, the diffusion ratio of methane concentration in upper-oil layer solution gas is 54% from middle Pliocene to the end of Quaternary.