塔里木盆地近临界油气藏相态特征

近临界流体相态变化非常复杂,易挥发油和凝析气的性质相近,常规方法难以判断其是油藏还是气藏。以塔里木盆地塔中1号气田中古43井区和金跃201井2类近临界地层流体为研究对象,通过观测近临界"乳光现象",应用气油比、相图、密度及组分等不同方法对油气藏类型进行判定,综合不同方法对比研究表明:利用测试时流体图像与无因次压力关系曲线法相结合判断近临界流体类型比较准确;塔中1号气田中古43井区属于特高含凝析油凝析气相态特征,金跃201井属于近临界挥发油相态特征。通过注气实验,近临界油气藏出现干气、凝析气、凝析液三相共存的流体特征,造成不同位置的生产井气油比差异较大。

Phase behavior characteristics of near-critical oil and gas reservoirs in Tarim Basin

The phase behavior of near critical fluid is very complex,and the similar properties of volatile oil or condensate gas result in the difficulties to judge whether it is an oil reservoir or a gas reservoir by conventional methods. Two types of near critical formation fluids,Zhonggu 43 well area and Well Jinyue 201,Tarim Basin,are studied. By observing the near-critical "emulsion phenomenon",different methods such as gas-oil ratio,phase diagram,density and composition are used to judge the types of oil and gas reservoirs. By comparing different methods,the near-critical fluid types can be judged accurately by combining the fluid image and dimensionless pressure curve method during testing. The Zhonggu 43 well area of Tazhong 1 Gas Field is characterized by the condensate gas phase with very high condensate content,while Well Jinyue 201 is characterized by the phase of near critical volatile oil. Through gas injection experiments,the near-critical reservoirs have threephase coexistence of dry gas,condensate gas and condensate liquid,resulting in large differences in gas-oil ratio of production wells at different locations.