一种利用生产数据评价苏里格低渗气井产能的新方法

A New Method for Evaluating the Productivity of Gas Wells in Sulige Low Permeability Reservoirs by Using the Production Data

为实现苏里格低渗气井产能实时评价、确定合理工作制度,针对地层压力监测及产能测试时间长、常规试井应用规模受限、开发方式特殊等问题,本文通过气井产能评价方法综合分析,在利用井口压力考虑节流状态确定井底流压的基础上,运用气井的生产数据对单井产能进行评价,并据此计算地层压力、产能方程系数a和b,建立产能方程实现气田实时产能评价,确定单井合理产能与气田生产能力。研究表明:①在气井渗流达到拟稳态的条件下,可以用常规的压力平方二项式方程来求取低渗气藏的产能方程和无阻流量;②苏里格带井下节流装置的低渗气井考虑节流状态比不考虑节流状态的压力要高出3.09~9.48 MPa;③利用此方法对研究区10口井的地层压力、无阻流量进行计算,并与产能测试结果对比,计算误差在0.63%~4.3%,平均误差仅为2.4%。以上成果认识,对同类型低渗气藏开发具有借鉴和指导意义。

Sulige low permeability reservoirs in well head pressure, long well testing time, large high production loss. In addition, Sulige special development mode-downhole throttling and well head increasing technology, which are the challenges existing in the operation of formation pressure monitoring and well productivity testing of abnormal high-pressure gas reservoir which limits the application scale of conventional productivity testing. Through the research on the methods of gas well productivity evaluation, based on the bottom hole flow pressure determined by well head oil pressure while considering the throttling state to evaluate the single well productivity using the dynamic production data of gas field and on the basis of this to calculate the gas well formation pressure, laminar flow coefficient a, turbulent flow coefficient b, the gas well deliverability equation was established to evaluate the real-time productivity of gas field and to determine the reasonable productivity of single well and reasonable working system. The application example shows that: ①Under the condition that the gas well reaches quasi-steady state, the productivity equation and open flow rate of low permeability gas reservoir can be obtained by the conventional pressure square binomial equation. ②The pressure of low permeability gas well with downhole throttling device in Sulige belt is 3.09~9.48 MPa higher than without throttling condition. ③By using this method, the formation pressure and open flow of 10 wells in the study area are calculated. Compared with the productivity test results, the calculation error is 0.63%~4.3%, and the average error is only 2.4%. The above results can be used for reference and guidance for the development of the same type of low permeability gas reservoirs.