天然气运移相态及其变化

Gas Migration Phase and its Change

付广 薛永超

Fu Guang Xue Yongchao

大庆石油学院 黑龙江安达市 151400

Daqing Petroleum Institute

天然气运移相态是影响其运聚成藏的重要因素。其除了受源岩类型和演化阶段的影响外,还要受到其所处环境条件变化的影响。天然气既可以由水溶、油溶和扩散相向游离相转变,又可以由游离相向水溶、油溶和扩散相转变。前者有利于天然气运聚成藏,后者则不利于天然气运聚成藏。天然气运移相态的转变需要一定的地质条件。水溶相、油溶相向游离相转变均需要压力降低,而扩散相向游离相转变则需要遇到烃浓度盖层或气层。实例分析表明,由其他相态向游离相转变而来的天然气均可成为天然气富集成藏的重要组成部分。

Gas migration phase is an important factor influencing gas accumulation and distribution. Gas migration phase was influenced by change of pressure acceptted by organic matter type of gas sourcerock and evolution stage. Gas in water -dissolved phase, in oil -dissolved phase and in diffusive phase can change into gas in free phase. Gas in free phase can change into gas in water -dissolved phase, in oil -dissolved phase and in diffusive phase. Former is favorable for gas to accumulate and form gas pools, Latter is not favorable for gas to accumulate and form gas pool, The change of gas migration phase requires certain geological conditions. Change of gas in water -dissolved phase and in oil -dissolved phase into gas in free phase requires decrease of pressure. Change of gas in diffusive phase into gas in free phase requires concentration caprock or gas -bearing layer.The analysis of actual examples indicates that the gas in free phase released from gas in water -dissolved phase, in oil -dissolved phase and in diffusive phase is the important part for gas to accumulate and form gas pool.