台北凹陷侏罗系煤层残留气量数值模拟

在分别考虑各种相态残留气量影响因素并建立相应定量关系的基础上 ,采用排烃门限理论和物质平衡法 ,对吐哈盆地台北凹陷侏罗系煤层残留气量进行了数值模拟。模拟结果表明 ,煤中残留的气主要以水溶、油溶、游离和吸附 4种相态存在 ,其中油溶相和吸附相起决定作用。与炭质页岩和泥岩相比 ,煤的残留气量最大。台北凹陷 1m3 煤岩残留甲烷气和重烃气的量分别为 10 .64m3 和 2 .3 84m3 ,煤岩残留气量随埋深先增大后减小。台北凹陷中、下侏罗统煤层残留气量分别为 5 .63× 10 12 m3 和 13 .12× 10 12 m3 ,在该区适合开展煤层气勘探。图 2参 3

A numerical simulation on amount of remained gas in Jurassic coal-measure strata in Taibei sag

On the basis of studying the influence factors on amount of remained gas in all phases and establishing the corresponding quantitative relations respectively, a numerical simulation on amount of remained gas in Jurassic coal-measures strata in Taibei sag, Turpan-Hami basin was carried out by using the theory of hydrocarbon expulsion threshold and the material balance method. The results show that main mechanisms of gas retained in coal-measure strata include dissolution in formation water, free phase, dissolution in oil and diffusion, with the last two being the most important. Comparing Carbonaceous shale with mudstone, the amount of remained gas in coal is the largest. In the studied region, the amount of methane and heavier hydrocarbon gases remained in 1m3 coal source rocks is 10.64m3 and 2.384m3, respectively. With the burial depth increasing,remained gas in coal measure strata increases firstly, but decreases later. The total amount of remained gas in the middle and the lower Jurassic coal-measure strata is 5.63×1012m3 and 13.12×1012m3, respectively. It is suitable to explore coal-bed gas in Taibei sag.