临汾区块深层煤层气水平井定量化排采控制技术

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

为了实现临汾区块深层煤层气水平井定量化的排采控制,基于兰格缪尔等温吸附理论和生产特征分析,建立了煤层气水平井排采阶段划分方法,并通过计算确定了压降速度、理论稳产气量等关键控制参数,形成了五段三压式排采控制技术,即以产气变化为依据,将水平井排采过程划分为未见气、憋套压、产气上升、产气稳定与产气衰减5个阶段,再以初始压力、解吸压力、稳产压力为3个关键控制节点,计算得到未见气阶段压降速度为10~12 kPa/d,憋套压阶段暂缓降压,产气上升阶段压降速度为8 kPa/d,产气稳定阶段压降速度不超过2.5 kPa/d,产气衰减阶段压降速度为0.4 kPa/d。实践结果表明:五段三压式排采控制技术可操作性强,能够有效指导生产管理,实现深层煤层气水平井排采的定量化控制。

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.