深部煤层气井排采特征及产能控制因素分析

Analysis of the characteristics of deep coalbed methane wells drainage and control factors of productivity

根据鄂尔多斯盆地某区块深部煤层气井生产资料，分析深部煤层气井在排采初期的气水产出特征；研究影响深部煤层气井产能的地质和工程主要因素，基于产能主控因素提出研究区深部煤层气开发建议．结果表明：深部煤层气井在排采初期产能偏低，影响产气效果的地质因素主要包括构造部位、煤层埋深、含气量及水动力条件，工程因素主要包括压裂参数、开采层数和抽采制度；开发时应注意控制压裂液排量高于7．75m3／min，保持30～40m3的加砂量，并根据产气变化及时调节泵冲次，调节幅度以小于0．05次／min为宜；工程前期设计和后期操作要与地质情况紧密结合，充分发挥两者对产能控制的最大优势．

In China,few research aims at deep coalbed methane(CBM)production and the exploration and development of CBM has always focused on the shallow coal seam,whose burial depth is less than800 m.Based on the production data of some deep CBM wells from one of the blocks in Ordos basin,where there is large area of coal seam with burial depth more than 800 m,the gas and water-producing characteristics in the early stage of drainage are analyzed.Meanwhile the key factors that influence the deep CBM well productivity are studied from geology and engineering aspect.Depending on these control factors of productivity,some proposals for deep CBM development in the block are put forward.The result shows:the deep CBM well has a low productivity in the early stage of drainage.Tectonic position,coal seam burial depth,gas content and hydrodynamic condition are the primary geological factors affecting the gas-producing potential,and the engineering factors mainly include parameters of fracturing,amount of coal seams for development and drainage working system.During the developing process,special attention should be paid to controlling the volume of fracturing fluid more than 7.75m3/min and the amount of sand at 30~40m3.The pump stroke of CBM wells should be adjusted in time according to the change of gas production and the range within 0.05beats/min is appropriate The geological conditions should be closely connected with the early design and later operation of engineering,contributing their maximum advantage to productivity control.