物理模拟技术在沁水煤层气藏水动力研究中的应用

Application of physical simulation in the study of hydrodynamic conditions of Qinshui coalbed methane reservoir

通过煤层气成藏模拟实验,研究了水动力条件对煤层气成藏的控制作用。实验结果表明:在强烈的水动力交替作用下,煤层气藏中的甲烷碳同位素由-29.50‰变为-36.60‰,且变轻过程中具有阶段性特征;甲烷体积分数由96.35%减小为12.42%;二氧化碳由0.75%变为0.68%,随后增大到1.13%;氮气体积分数由2.9%变为86.45%。这些变化一方面说明煤层气成藏过程的复杂性,另一方面表明强烈的水动力作用对煤层气成藏会造成不利影响。通过对以高煤阶为典型特点的沁水盆地南部水动力条件的分析,认为径流强度与煤层含气量之间呈负相关性,弱径流区有可能成为高煤阶煤层气富集的高产区。

Using the CBM reservoir simulation facilities,the action of hydrodynamic force controlling coalbed methane（CBM） reservoir formation was studied in this paper.The results of experiment showed that under the strong hydrodynamic alternation,δC1 of coalbed methane reservoir changes from -29.50‰ to -36.60‰,and the lightening process was characterized by phases;CH4 volume content was reduced from 96.35% to 12.42%;CO2 content decreased from 0.75% to 0.68%,then rised to 1.13%;N2 content changed from 2.9% to 86.45%.On one hand,these changes showed the complexity of CBM reservoir formation,on the other hand,they indicated that the strong hydrodynamic action had unfavorable impact on CBM reservoir formation.Meanwhile,the hydrodynamic condition of Qinshui basin with high coal rank was analyzed,and it was found that gas content and hydrodynamic intensity had negative correlation,low hydrodynamic flow condition might result in the high productive and en-richment area of high rank CBM.