论文部分内容阅读
煤层气解吸阶段的定量描述是客观认识煤层气井产能、诊断煤层气井生产状况及优化排采管理的重要基础.本文基于沁水盆地南部6口煤层气井的12件无烟煤样品进行了一系列的等温吸附实验,并以此为基础,建立了一种以朗格缪尔吸附理论为基础的解析模型.运用此模型,建立了以等效解吸率及其曲线特征来刻画煤层气解吸阶段性的数值方法.通过实验和数值描述,以等效解吸率曲率为依据,提出并确定了启动压力、过渡压力和敏感压力三个定义降压解吸阶段的关键压力点.在此基础上,将等温吸附实验下煤层气的解吸过程划分为四个阶段,即零解吸阶段、缓慢解吸阶段、过渡解吸阶段和敏感解吸阶段.通过类比分析,发现等温吸附实验条件下的煤层气解吸阶段性与煤层气井产气过程的异同之处,认为较高的朗格缪尔体积和朗格缪尔常数比有利于稳产阶段的及早到来,但也可能使煤层气产能递减阶段提前出现.
Quantitative description of CBM desorption stage is an important basis for objective understanding of CBM production capacity, diagnosis of CBM production status and optimization of discharge management.Based on a series of isothermal adsorption of 12 anthracite samples from 6 CBM wells in southern Qinshui Basin, Based on this, an analytical model based on Langmuir adsorption theory was established.Using this model, a numerical method was established to characterize the stage of desorption of coalbed methane with equivalent desorption rate and its curve characteristics Based on the experimental and numerical description, the key pressure points in the desorption and desorption stage are defined and determined based on the equivalent desorption curvature, and the initial pressure, transition pressure and sensitive pressure are determined and determined. Under the isothermal adsorption experiment The process of desorption of coalbed methane is divided into four stages, namely zero desorption stage, slow desorption stage, transition desorption stage and sensitive desorption stage.According to the analogy analysis, it is found that the desorption stage of coalbed methane and the gas production process of CBM well under isothermal adsorption experiment Similarities and differences between the point that the higher Langmuir volume and Langmuir constant ratio is conducive to the early stage of stable production, It may also make coalbed methane production declining phase appeared earlier.