基于LBM方法微孔裂隙模型内CO2驱替CH4过程吸/脱附特性研究

Research on the adsorption/desorption characteristics of CO2 displacement CH4 in a microporous fracture model based on LBM method

中文关键词: 格子-Boltzmann方法  驱替过程  吸脱附特性  吸/脱附速率

英文关键词: Lattice Boltzmann Method  displacement process  adsorption/desorption characteristics  adsorption/desorption rate.

中文摘要:

      为探究CO2强化页岩气开采机理，结合VC++编程技术利用格子-Boltzmann方法（Lattice Boltzmann Method，简称LBM）对微孔裂隙模型内CO2驱替CH4过程开展数值模拟研究。基于单分子吸附层假设，推导建立了双组分气体竞争吸附的吸附速率方程。分别在单颗粒模型和以四参数生成法（Quartet Structure Generation Set，简称QSGS）随机生成的多孔介质为模型的基础上，利用LBM方法对CO2驱替CH4过程开展数值模拟研究。结果表明：在CO2驱替CH4的过程中，两种气体的吸/脱附速率均存在极值，且CH4的脱附速率极值点先于CO2的吸附速率极值点出现。增加CO2注入速度和注入浓度均有利于提高驱替效率，同时CO2的注入速度和注入浓度越大，驱替过程中CO2/CH4达到吸附/解吸平衡所需时间越短。

英文摘要:

      To explore the mechanism of CO2 enhanced shale gas extraction, a numerical simulation study of Lattice Boltzmann Method (abbreviated as LBM) was conducted by using VC++ programming technology to investigate the CO2 displacement process of CH4 in a microporous fracture model. Based on the assumption of a single-molecule adsorption layer, an adsorption rate equation for competitive adsorption of two-component gases was derived and established. Based on the single particle model and the porous media randomly generated using the Quart Structure Generation Set (QSGS) method, numerical simulation studies were conducted using the LBM method to investigate the CO2 displacement process of CH4. The results show that in the process of CO2 displacement of CH4, there are extreme values in the adsorption/desorption rates of both gases, and the extreme point of CH4 desorption rate appears before the extreme point of CO2 adsorption rate. Increasing the injection rate and concentration of CO2 is beneficial for improving displacement efficiency. The higher the injection rate and concentration of CO2, the shorter the time required for CO2/CH4 to reach adsorption/desorption equilibrium during the displacement process.