CAJ | 학술논문

建立一种注气驱替煤层气的双重介质数学模型，考虑注气驱替煤层气中多组分气体渗流、吸附/解吸、扩散及孔隙度和渗透率敏感性等多物理场的耦合，用有限差分方法对数学模型数值求解，并验证模型的有效性。通过实例模拟，对比分析注入CO2、N2和70％N2＋30％CO2提高采收率、产出组分动态及储层物性。计算表明：注入CO2、N2及其混合气体均能显著提高煤层气藏采收率，提高程度可达28％以上； N2在注入后迅速突破产出，而CO2突破时间较晚；注气后基质的收缩/膨胀效应在孔隙度和渗透率敏感性中起主导作用，CO2吸附造成孔隙度和渗透率减小，而N2吸附将增大孔隙度和渗透率。
건립일충주기구체매층기적쌍중개질수학모형，고필주기구체매층기중다조분기체삼류、흡부/해흡、확산급공극도화삼투솔민감성등다물리장적우합，용유한차분방법대수학모형수치구해，병험증모형적유효성。통과실례모의，대비분석주입CO2、N2화70％N2＋30％CO2제고채수솔、산출조분동태급저층물성。계산표명：주입CO2、N2급기혼합기체균능현저제고매층기장채수솔，제고정도가체28％이상； N2재주입후신속돌파산출，이CO2돌파시간교만；주기후기질적수축/팽창효응재공극도화삼투솔민감성중기주도작용，CO2흡부조성공극도화삼투솔감소，이N2흡부장증대공극도화삼투솔。
A double medium mathematical model for coalbed methane displacement with gas injection is established. Multi-physics coupling process containing Darcy flow, adsorption/desorption and diffusion of multiple component gas and variation of porosity and permeability is involved. The model is solved numerically with finite difference method and validity of the model is verified. In example simulation calculations, improved recovery, evolution of produced gas composition and variation of coal seam properties under injection of CO2、N2 and 70%N2 +30%CO2 are contrastively analyzed. It indicates that injections of CO2、N2 and their mixed gas are able to improve coalbed methane recovery significantly by a degree over 28%. N2 breaks through rapidly after injected, while CO2 occurs in production well later. Shrinkage/swell effect plays a dominant role in variation of porosity and permeability after gas injection. Adsorption of CO2 reduces porosity and permeability, while adsorption of N2 leads their increase.