煤矿采动稳定区煤层气资源评估方法及其应用

摘要

受多煤层赋存条件和煤矿井下回采工艺影响,采空区内的大量遗煤导致废弃矿井或老采空区内赋存丰富煤层气资源,对这一资源的准确评估、合理开发和高效利用是我国进行非常规油气资源开发的重大需求,如何准确评估废弃矿井或老采空区的可抽采煤层气资源量是进行高效开发的关键问题.因此,通过分析煤层气的来源、赋存空间和关键影响因素,建立了基于“间接减法”理念的采动稳定区(废弃矿井或老采空区)煤层气资源评估模型,提出了进行采动稳定区煤层气资源评估的方法.运用建立的评估模型和方法,在晋城矿区成庄矿5310工作面区域进行了采动稳定区煤层气资源的地面井抽采试验,单井连续抽采433 d,抽采煤层气资源243.27万m3,抽采量核算与评估结果基本一致,初步证明了评估方法的适用性.%Influenced by the condition of multiple coal seams and coal mining technology in China,a large number of abandoned coal in the goaf leads to rich coalbed methane resources in abandoned mines or old mined out areas.Reasonable development,accurate assessment and efficient use of the resources of China's unconventional oil and gas resources are significant issues and how to accurately assess the mine goaf or the drainage of coalbed gas resource is the key problem which should be resolved first.Based on the analysis of the source,space and key influencing factors of coalbed methane,the evaluation model of coalbed methane resources in the mining stability zone (abandoned mine or old goaf) was established based on the idea of ‘indirect subtraction’ and a method was presented for mining stable coalbed gas resource assessment.Based on the assessment model and method a surface borehole drainage test of coalbed methane resources in the mining stability area had been carried out in the 5310-workface area of Chengzhuang Mine in Jincheng mining area.Single surface borehole was continuously drained for 433 days and the drainage of 2 432 700 m3 CBM resources was achieved.The drainage quantity calculation result and the evaluation result are basically the same.The preliminary result proves the applicability of the evaluation method.