泊里井田煤层气储层物性特征及地面抽采可行性分析

Physical Characteristics of CBM Reservoir and Feasibility Analysis of Surface Pumping in Poli Mine

依据煤田勘探地质资料、煤层气参数井储层资料,采用“定性+定量”相结合方法,分析泊里井田煤层埋深、含气性、渗透性及抽采参数等物性特征。并结合首采面煤层气XX-1井工程效果,分析区内地面抽采可行性。认为区内煤层埋深适中、盖层条件良好,资源条件较好,煤层资源量6.590×10^(9)m^(3)。煤储层含气饱和度、临界解吸压力较高,存在降幅空间。煤层气XX-1井采用“投球压裂+控压排采”组合方式,有效提高裂缝延伸长度和降落漏斗扩展范围,实现单井产气量1000 m^(3)/d的突破。地面抽采可行。直井/丛式井井网地面抽采产能预测,3~5 a理论采收率8.12%~17.33%,时效性偏低,难以满足煤矿生产区或者准备区“抽-掘-采”供需平衡。结合区内15煤层上部岩层结构,建议开展地面水平井高效抽采治理模式工程试验。

Based on the geological data of coalfield exploration and the reservoir data of coal-bed methane parameter wells,the method of"qualitative+quantitative"is adopted to analyze the physical characteristics of the coal seam burial depth,gas bearing property,permeability and extraction parameters in the Poli well field.Combined with the engineering effect of coal-bed methane well XX-1 in the first mining face,the feasibility of surface pumping in the area is analyzed.It is considered that the burial depth of the coal seams in the area is moderate,the cap-rock conditions are better,and the resource conditions are better.The coal seam resource amount is 6.590×10^(9) m^(3).The gas saturation and critical desorption pressure of coal reservoir are higher,and there is room for decreasing.The coal-bed methane XX-1 well adopts the combination mode of"ball fracturing+pressure controlling drainage",effectively improving the fracture extension length and the extension range of the falling funnel,and achieving a breakthrough in the daily gas production of 1000 m^(3)/d for a single well.Ground pumping is feasible.According to the prediction of the surface extraction capacity of the vertical well/cluster well pattern,the theoretical recovery rate in 3-5 years is 8.12%-17.33%,with low timeliness,which is difficult to meet the supply and demand balance of"pumping-driving-mining"in the coal production area or preparation area.In combination with the upper rock structure of coal seam 15 in the area,it is suggested to carry out the engineering test of high efficiency extraction treatment mode of surface horizontal wells.