和田河气田水溶气成藏特点对克拉2气田的启示

塔里木盆地克拉2气田天然气成藏倍受关注,存在许多疑惑有待于解决。本文根据和田河气田水溶气成藏地质条件和成藏特点,认为克拉2气田具有更优越的水溶气成藏条件,拜城凹陷中生界煤系烃源岩生成的天然气在深部高温、高压状态下大量溶解于水,以水溶气的形式保留在深部地层中,而新构造运动产生了断层相关褶皱,深部的水溶气便沿断裂往上运移至第三系和白垩系圈闭中并随温度和压力降低脱气成藏,从而使天然气具备水溶气的某些特征。指出克拉2气田气-水界面以下的高压水体中未释放出的天然气储量也相当可观,随着气田开发,压力降低,水体中天然气会不断释放,这对该气田天然气可采储量和开采年限的重新估算都有重要的意义。

IMPLICATION TO KELA 2 GAS FIELD FROM WATER\|SOLUBLE GAS\= ACCUMULA TION IN HETIANHE GAS FIELD

The gas accumulation in the Kela 2 gas field has been widely noticed. There remain some problems still to be solved. Drawing lessons from the water-soluble gas accumulation condition and characteristics in the Hetianhe gas field, this paper indicates that the Kela 2 gas field has an even better water-soluble gas accumulation condition. The gas generated from the Mesozoic coal measure source rocks could be dissolved in water in a great deal at high temperature and pressure and kept in deeper layers in the form of water-soluble state. As the Neotectonics had created fault-related traps, the water-soluble gas in deeper layers migrated along faults up to Tertiary and Cretaceous traps. The gas with some traces of water-soluble origin then released from water when the temperature and pressure deceased, and the gas pools were formed in this way. Simulative calculation shows that the water can release abundant gas when migrating to the shallow part. The unreleased gas at high pressure water body under the water-gas interface has a largish reserve, too. With the development of the gas field, the gas in water can release gradually. This has much significance for the reassessment of the recoverable reserves and exploitation years.