低渗透煤层气产气通道渗流门限分析  

Analysis on percolation threshold of low permeability coalbed methane gas channel

作　　者：张芬娜[1,2] 李明忠 綦耀光[1] 陈波[1] 孟尚志[3] 

机构地区：[1]中国石油大学(华东)机电工程学院,山东青岛266580 [2]中国石油大学(华东)石油工程学院,山东青岛266580 [3]中联煤层气有限责任公司,北京100108

出　　处：《中国矿业大学学报》2015年第6期1025-1032,共8页Journal of China University of Mining & Technology

基　　金：国家科技重大专项(2011ZX05062-004);国家自然科学基金项目(51174224);青岛博士后资助项目(T1402021)

摘　　要：基于毛细管模型和渗流能量方程,考虑煤层气在产气通道渗流过程中解吸吸附的动态平衡,建立了产气通道门限渗流模型,给出煤层气渗流的临界半径和临界长度,并基于门限渗流模型,引入产气通道连通程度对单井产气量进行预测.结果表明:产气通道的临界渗流直径的数量级是微米级(μm),也就是说在煤层中小于微米级裂隙主要是气体扩散的通道,对气体渗流贡献较小;不同直径产气通道解吸气体渗流的长度不同,裂缝宽度小于5mm时,只是煤层气井周围1m范围内的产气区域,当产气通道的直径大于14mm时,在不同临界解吸压力下其控制区域半径在50m以上,增加煤层气产气通道的尺度和连通程度可增加煤层气单井控制的渗流区域,提高煤层气井产气量,为煤层气井区域性排采、井网优化设计提供依据.Based on the capillary model and seepage energy equation,agas channel percolation threshold model was established in view of the coalbed methane desorption-adsorption dynamic balance in the process of seepage.Meanwhile,the critical radius and critical length of coalbed methane seepage were obtained,and the gas channel connectivity degree was adopted to forecast the gas production rate of single well based on the percolation threshold model.The results show that the critical percolation diameter of gas channel is micron order（μm）,which suggests that coal seam fissures less than macron size are gas diffusion channels,hardly contributing to any gas seepage.Seepage area of desorption gas in channels with different diameters are distinctive,when the width of the fissure is less than 5mm,the area of seepage flow only covers gas province 1maround the coalbed methane well;when the diameter of the gas channel is greater than 14 mm,and under different critical desorption pressure,the seepage scope can spread more than 50 maround the well.Increasing the size of the gas channel and the connectivity degree can broaden the single well controlled seepage area and improve the gasproduction rate of coalbed methane wells.This paper will provide a basis for regional gas exploitation and well pattern optimization design.

关 键 词：渗流门限 连通程度 产气量 区域排采 

分 类 号：P618.11[天文地球—矿床学]