基于LBM方法的井间干扰对煤层气排采的影响机理分析

为了探明煤层气排采井间的相互干扰机制对合理布设井网、提高煤层气采收率的影响,采用LBM数值模拟方法再现了煤层气从割理空间至排采井口的运移过程,并系统分析了不同排采参数及井间干扰对产气量的影响机理。结果表明,井间干扰导致井筒间产气量差异随井间距的变化表现出波动起伏特征;若考虑单井产气量,井间干扰对产气量具有分段效应,当井间距Ds小于382.5 lu(lu为模拟格子长度单位)时为抑制作用,反之为促进作用;过小的井间距不利于煤层气排采,井间距超过临界阈值382.5 lu时,可加快煤层气的采收速率;井口平均流速v同压力差△p满足幂率关系v≈3.2△p^0.94。

Analysis of Influence Mechanism of Interference Mode Between Drainage Wells on CBM Extraction Based on LBM Method

It is of great significance to find out the mutual interference mechanism between CBM drainage wells to rationally arrange well networks and improve CBM recovery.To this end,Lattice Boltzmann Method(LBM)was used to reproduce the migration process of CBM from cleat space to drainage wellhead,and the influence mechanism of different drainage parameters and mutual interference between CBM drainage wells on gas production were systematically analyzed.The results showed that the difference of gas production between wellbores showed fluctuation characteristics with the change of well spacing due to inter-well interference.If single well gas production was considered,inter-well interference had segmented effect on gas production.When the spacing of Dsbetween wells was less than 382.5 lu,it showed inhibiting effect;otherwise,it showed facilitation.Too small well spacing was not conducive to CBM production.When the well spacing exceeded the critical threshold of 382.5 lu,the recovery rate of CBM could be accelerated.The power law relationship v≈3.2△p^0.94 was followed by mean velocity v of CBM in wellhead and pressure difference △p.