Quantitative control technology for deep coalbed methane horizontal wells in Linfen Block

In order to achieve quantitative control for extracting the deep coal bed methane of horizontal wells in Linfen block, a kind of control technology of four stages and three pressure is found out, which is based on Langmuir isothermal adsorption theory and production characteristics analysis.It is inclusive of a method of pro-duction stages division of horizontal well in CBM and the quantification of some key control parameters, such as pressure drop rate and theoretical production.Firstly, considering the change of gas production, the drainage pro-cess is divided into five stages, i.e.no gas period, casing pressure rising period, gas production rising period, gas production stable period, and gas production decline period.Secondly, according to the three key control factors of initial pressure, desorption pressure and steady production pressure, the theoretical pressure drop rate can be obtained by calculation.It is 10-12 kPa/d in no gas period, 8 kPa/d in gas production rising period, and less than 2.5 kPa/d in gas production stable period, and 0.4 kPa/d in gas production decline period.Ihe technology of four stages and three pressure can be applied effectively in CBM production management, and the quantitative control can be set up in deep CBM of horizontal well.