CAJ | 학술논문

针对煤层的双重孔隙特性，采用考虑了Fick第一扩散定律和考虑有效应力的渗透率模型对煤层气的开采过程进行研究，探讨了扩散系数对煤层气开采的影响作用。采用不同的扩散系数值（1．2×10－10 m2／s与1．2 ×10－13 m2／s），通过数值计算，对煤层气的产量演化过程进行分析。计算结果表明：扩散作用主导的煤层气生产过程要远远长于自由相气体主导的煤层气生产过程，具体来说，基质气体压力演化过程的时间尺度（109 s ）比裂隙气体压力演化的时间尺度（107 s ）要高两个数量级；在煤层气解吸过程初期，不同的基质扩散系数对产量的影响不明显；在解吸过程后期，两种情况下单位时间内的煤层气产量相差很大，最终可达到三个数量级。
침대매층적쌍중공극특성，채용고필료Fick제일확산정률화고필유효응력적삼투솔모형대매층기적개채과정진행연구，탐토료확산계수대매층기개채적영향작용。채용불동적확산계수치（1．2×10－10 m2／s여1．2 ×10－13 m2／s），통과수치계산，대매층기적산량연화과정진행분석。계산결과표명：확산작용주도적매층기생산과정요원원장우자유상기체주도적매층기생산과정，구체래설，기질기체압력연화과정적시간척도（109 s ）비렬극기체압력연화적시간척도（107 s ）요고량개수량급；재매층기해흡과정초기，불동적기질확산계수대산량적영향불명현；재해흡과정후기，량충정황하단위시간내적매층기산량상차흔대，최종가체도삼개수량급。
Based on the dual‐porosity characteristics of coal seams ,Fick’s First Law for Diffusion and the permeability model considering the effective stress impact was included to investigate the impact of the diffusion coefficient on coalbed methane recovery .The evolution of gas output was analyzed in two different scenarios with different diffusion coefficients(1 .2 × 10-10 m2/s and 1 .2 × 10-13 m2/s) .The results showed that the gas recovery process dominated by diffusion was much longer than that dominated by the gas in free phase .The time scale for the evolution of matrix gas pressure(109s)was two magnitudes larger than that of fracture gas pressure(107s) .The diffusion coefficient has unobvious influence on the gas recovery in the initial stage ,but the difference developed with the recovery process and reached 3 magnitudes finally .