为了深入研究煤层气井合理配产及其排采控制方法,延长气井高产稳产期,通过对延川南煤层气田煤层等温吸附特征与气井生产参数进行对比研究,提出了煤层气井合理配产方法,并在现场煤层气井排采参数及动态规律对比分析基础上,以煤储层压力、临界解吸压力、兰氏压力、稳产压力为关键控制节点,将延川南煤层气井排采过程划分为5个阶段,对各阶段排采参数控制进行了研究。结果表明:延川南煤层气田煤层气井井底流压在煤层兰氏压力附近时,产气量达到峰值,煤层气井的稳产气量与峰值产气量,以及稳产流压与兰氏压力之间有较好的线性关系,得出的拟合公式,可以计算各井合理稳产流压和稳产气量。5个排采阶段,分别是快排期、缓慢降压排水期、上产期、产量波动期和稳产期。对于延川南煤层气田,快排期日降井底流压在0.1 MPa左右较为合理,缓慢降压排水期、上产期和产量波动期排采控制非常关键,缓慢降压排水期日降井底流压在0.003 MPa左右,上产期谭坪构造带气井日降井底流压要小于0.005 MPa,万宝山构造带要小于0.01 MPa,产量波动期日降井底流压要控制在0.003 MPa左右。

In order to further study the reasonable production allocation and drainage control method, and extend the high and stable production period of CBM wells, the reasonable production allocation is proposed by comparative researches on the isothermal adsorption of coal bed and production parameter of CBM wells in South Yanchuan CBM field. On the basis of the comparative analysis of the parameters and dynamic regulation of coalbed methane drainage on site, and taking coal reservoir pressure, critical desorption pressure, Langmuir pressure and stable production pressure as the key control nodes, the drainage process of CBM wells can be divided into five stages, and then the method of production parameter control during every drainage stage is studied. The result shows that the gas yield peak appears when the bottom hole flowing pressure is at about Langmuir pressure of coal bed in South Yanchuan CBM field. There is a good linear relation between the stable gas production and the peak gas production, as well as that between the stable flowing pressure and the Langmuir pressure. The fitting formula can be used to calculate the reasonable stable flowing pressure and stable yield of each well. The above five stages are fast drainage stage, slowly pressure drop drainage stage, gas yield rising stage, gas yield fluctuation stage, and stable yield stage. For the South Yanchuan CBM field, the reasonable bottom hole flowing pressure drop is about 0.1 MPa/d during the fast drainage stage. The drainage control at slowly pressure drop drainage stage, gas yield rising stage, and gas yield fluctuation stage are very important. The bottom hole flowing pressure drop should be about 0.003 MPa/d during the slowly pressure drop drainage stage, less than 0.005 MPa/d during the gas yield rising stage in Tanping structural belt, less than 0.01 MPa/d in Wanbaoshan structural belt, and about 0.003 MPa/d during the gas yield fluctuation stage.