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据《中国石油报》介绍:近年来,四川的石油地质学家经过研究,认为四川威远的震旦系气藏是由水溶气脱气而成的。威远气田的震旦系在喜马拉雅期褶皱前,埋深7500m,地层水中天然气溶解量为7.5m~3(气)/m~3(水);喜马拉雅期褶皱后,震旦系上隆至埋深2800m,地层压力从77.7MPa 下降为现今的28.0MPa,地层温度从219℃降为90℃。由于地层压力和温度的下降,使得地层水中溶解气大量逸出,估算每立方米的水中逸出的天然气达5m~3。这些水溶气的脱溶气充满了威远背斜顶部25%的圈闭空间,形成了储量达400×10~8m~3的大气田。
According to the “China Petroleum News” description: In recent years, Sichuan petroleum geologists after the study that the Sinian gas reservoir in Weiyuan, Sichuan is degassed by the water-soluble gas. Before the Himalayan fold, the Sinian in Weiyuan Gasfield buried at a depth of 7500m and dissolved natural gas in the formation water was 7.5m 3 (gas) / m 3 (water). After the Himalayan fold, the Sinian uplift to the buried depth 2800m, the formation pressure drops from 77.7MPa to 28.0MPa today, and the formation temperature drops from 219 ℃ to 90 ℃. Due to the decrease of formation pressure and temperature, a large amount of dissolved gas in formation water is released, and the estimated natural gas released per cubic meter of water reaches 5m ~ 3. The desolvation of these water-soluble gases fills the trapped space of 25% at the top of Weiyuan anticline, forming a large gas field with a reserve of 400 × 10 ~ 8m ~ 3.