煤层气开采研究主要有两个重要环节，其一是最大限度使煤储层中吸附态甲烷脱离煤基质表面，成为游离气，即煤层气解吸；二是使储层中转化为游离态的甲烷气体最大限度产出，即煤层气排采。而在生产中，后者往往对前者起着促进作用，因为煤层气解吸需要储层压力降低至临界解吸压力之下，目前采用的手段主要是排水降压，若压降漏斗不能向外延伸，煤储层压力降亦不能有效向远处传递，煤储层压力降将受到限制，煤层气亦不能解吸出来。通过对大佛寺井田煤层气井排采过程中储层压降特征、影响半径变化规律及产气量控制模型建立的研究，将对开采区煤层气的开发具有参考价值。 本文主要利用渗流力学原理，分析了煤层气垂直井与水平井随排采进行储层压降特征和压力分布规律。用地下水动力学原理，以导水系数表征煤储层渗透性，建立其与煤储层在排采过程中的影响半径计算模型。在研究大佛寺储层孔、裂隙及渗透率特征基础上，利用研究区典型垂直井和水平井的历史排采资料，进行了排采阶段划分，通过模型计算煤层气井不同排采阶段导水系数，然后根据Jacob公式计算垂直井影响半径，利用等面积转化得到水平井渗流边界，最后根据煤层气吸附解吸特征及压降规律建立了气井产气模型并应用于大佛寺井田。 分析大佛寺井田垂直井和水平井产气模型结果，两者的计算结果与实际排采相近。煤层气直井排采曲线表现出“驼峰式”，最终计算产气量稳定在2200 m3/d左右；水平井排采曲线呈“单峰式”，计算结果显示最高产气量为34000 m3/d，排采曲线产气量随着井底流压的降低而增加，产气先增大再减小，符合煤层气井产气规律。产气模型在大佛寺井田中能很好的应用，并利用预测曲线对大佛寺井田煤层气井排采工作制度提出调整建议，以提高煤层气井的产气量和延长稳产时间。

There are two important aspects of studying on coal bed gas mining. One is to maximize desorbed methane from coal reservoir surfaces, let the methane become free gas. This is coalbed methane desorption. The other is maximum output the free methane gas, this is coalbed methane drainage. In the production of coalbed gas, the latter plays a role in promoting to the former. Because coalbed methane desorption needs the reservoir pressure below its critical desorption pressure. Currently primary means is draining reservoir water, lowering its pressure. If the pressure drop funnel cannot extend, coal reservoir pressure drops will not transmit to distance effectively, coal reservoir pressure drop will be limited and coalbed methane will not be desorbed. Through the study of reservoir pressure drop characteristics, variation of radius of influence and production control model in process of CBM wells production will have reference value to the CBM development in Dafosi well field. The characteristics of pressure drop and pressure distribution with the CBM vertical and horizontal wells draining are analyzed using fluid mechanics in this paper. With conductivity characterization of coal reservoir permeability, establishing calculation model of conductivity and radius of influence in the process of CBM wells production using ground water dynamics. First, study on Dafosi mine reservoir pore and fracture and permeability characteristics. And then using the historical production data of typical vertical wells and horizontal wells in the study area divided the production stages. Through the model to calculate the conductivity of different production stages of the CBM wells. Then using Jacob formula to calculate the vertical radius and using principle of equivalent sizes obtained horizontal well boundary. Finally coalbed gas production model is established and applies to Dafosi mine base on the adsorption-desorption characteristics of CBM and the rule of reservoir pressure drop. We found similar model results with actual production data base on analysis of Dafosi vertical wells and horizontal wells in gas production model results. The CBM vertical drainage curves showing "camel type", the result shows eventually calculated gas production at around 2200 m3/d. The horizontal well production curve is "peak type", the result shows the maximum gas production for 34000 m3/d, and production curve shows gas production increase with the bottom-hole pressure decrease, the gas production first increased and then decreased, it conform to gas production rules of CBM wells. The model was applied well in Dafosi mine. And making adjustments to the CBM well draining technology using the predicted curve in Dafosi mine to enhance the CBM production and extend its stable hours.