榆林气田气井废弃条件的确定

榆林气田是典型的低渗透气田，要准确计算其采收率和可采储量，必需确定气井的废弃条件。传统方法对气井的废弃地层压力进行计算时，由于忽视了开发过程中产能方程的变化，造成计算结果存在一定的误差。根据气井废弃地层压力的相关理论和计算方法，考虑了对气井产能方程影响较大的参数的变化，结合榆林气田气井矿场实际，推导出了适合榆林气田计算气井任意时刻二项式方程系数的公式，进而得到气井废弃时的稳定二项式方程。根据垂直管流法计算得到废弃井底流压，从而得到可靠的气井废弃地层压力，再结合经济评价即可确定气井的废弃产量。实例计算表明，新方法实用、有效，更切合气田实际。

A new method of determining abandonment condition in Yulin gas reservoir

Yulin gas field is a typical low permeability gas field.Gas well abandonment condition must be determined to accurately calculate recovery factor and recoverable reserves.Traditional method neglects the change of productivity equation during development process when calculating abandonment formation pressure,resulting in certain error in calculation result.This paper takes account of the change of parameters that have big impact on gas well productivity equation according to relative theory and calculation method of abandonment formation pressure of gas well.Combining with gas well test in Yulin gas field,a binomial coefficient equation has been derived for Yulin gas wells at any moment,and a stable binominal equation of gas well abandonment is obtained.Bottom-hole producing pressure of abandonment well is calculated by vertical pipe flow method,thus achieving reliable abandonment pressure and determining gas well abandonment production in conjunction with economic evaluation.It has been proved that this method is practical and effective.