晋城岳城矿地面采动区井井位优选与抽采寿命研究

Study on the optimization of well location and extraction life in mining disturbed zone of Yuecheng mine in Jincheng

为了降低晋城岳城矿工作面U型通风造成的上隅角瓦斯聚集,提高采动与采空区煤层气地面井抽采井产量及抽采寿命,在借鉴成庄矿、寺河矿和赵庄矿等地面采动试验井研究及工程示范的基础上,以晋城岳城矿煤层气地质条件为工程设计依据,提出并优化地面采动区井位尽量靠近巷道位置处、大井眼地面钻井工艺、优化井身结构等设计方案。现场试验证明:部分采动区井通过避开采动应力卸载区及原位煤层高应力区优化布井,开采中包含3个阶段即卸压区抽采、新采空区抽采、老采空区抽采,达到了延长抽采井寿命的目的;但仍有部分采动区井在回采工作面推过井口后,煤气层抽采量迅速衰减至不产气,抽采寿命只包含两个阶段即卸压区抽采、新采空区抽采甚至仅卸压区抽采一个阶段。研究表明,优化后的大井眼钻井工艺及三开割缝套管井身结构设计对保持采动区井井身稳定,延长抽采寿命,保证采动区井产气运移通道畅通,提高抽采率起到了一定效果;采动区井煤气层抽采量和该井井筒位置至回风巷距离存在明显的负相关关系。岳城矿采动、采空区井基本不存在速敏效应,在井筒与裂隙带沟通良好的前提下,应选用大功率抽采设备抽采,可以有效扩展压降漏斗区域,其抽采影响半径水平方向可延伸至500 m以上。岳城矿地面采动区抽采取得了较好的效果,可在相似条件的煤矿区推广应用。

The aim of the study is to reduce the coalbed gas accumulation in the upper corner caused by U-type ventilation in the working face of Yuecheng Coal Mine,Jincheng City,and improve the production and extraction life of coalbed methane surface wells in the mining disturbed area and goaf.Based on the research of surface mining test wells in Chengzhuang Mine and Sihe Mine,and taking the geological conditions of coalbed methane in Yuecheng Coal Mine as the engineering design basis,this paper puts forward that the well location in the surface mining disturbed area should be close to the roadway location as far as possible,and the design scheme of large hole surface drilling method and optimization of wellbore structure was proposed.The field test shows that some wells in the mining area disturbed are optimized by avoiding the unloading area of mining stress and the relatively high stress area of in-situ coal seam,and the mining includes three stages,pressure relief area drainage,stable drainage in the mining area,drainage in the old goaf,so as to prolong the service life of the drainage wells.However,there are still some wells in the mining area whose gas drainage volume decreases rapidly after the working face is pushed over the wellhead until no gas is produced,the production cycle only includes two stages,pressure relief area extraction and stable extraction in mining area,or even only one stage of pressure relief area extraction.The research shows that the optimized large hole drilling technology and three split casing well structure design have a certain effect on maintaining the well stability in the mining area,prolonging the mining period,ensuring the smooth migration channel of gas production in the mining area,and improving the extraction rate.There is a significant negative correlation between the gas extraction amount and the distance from the wellbore position to the return air roadway in the mining area.Under the premise of good communication between wellbore and fracture zone,high-power pumping equipment should be selected for pumping,which can effectively expand the pressure drop funnel area,and its pumping influence radius can extend over 500 m horizontally.Yuecheng Mine surface mining pumping tests achieved good results,which can provide reference for mining areas with similar types of conditions.