井口产量不当调节对气藏产能预测影响的研究

气藏产能试井要求每一工作制度下的压力和产气量都必须保持恒定，在实际试井过程有时通过频繁地调节针型阀来保持工作制度的稳定，同时在试井解释过程中也常在其他参数不变的情况下，将变化的产气量或压力值仅进行简单平均后就直接带入方程进行计算，这些都会导致试井解释结果不准确，给气藏的合理配产及开发带来不利影响。基于气藏产能试井模型，阐述了二项式产能方程的适用条件，从机理上分析了频繁调节针型阀和仅将产气量和压力值进行简单平均对产能预测所造成的影响，并通过实例进行验证。结果表明：对产气量仅进行简单平均后就直接带入方程将改变二项式产能方程的系数，其系数B随计算所用产气量值的减小而增大，计算得到的无阻流量值随计算所用产气量数据的增加而增加，产气量增加1%，无阻流量增加约1.5%；对压力进行简单平均后带入方程有可能使二项式特征曲线出现异常。

A STUDY ON THE EFFECT OF IMPROPER ADJUSTMENT OF WELLHEAD PRODUCTION RATE ON PREDICTION OF GAS RESERVOIR PRODUCTIVITY

It is required that pressures and gas rates stay stable under each working system for deliverability test of gas reservoirs.In practical well tests,stability of the working system is realized sometimes by frequently adjusting the needle valve;and meanwhile,simple averaging is also used on varying gas rates or pressures for relevant calculations when other parameters are kept constant.All such operations can lead to inaccurate results of well test analysis and cause negative effect on reasonable production allocation and development of gas reservoirs.Based on the deliverability test model of gas reservoirs,this paper illustrates application specifications of binomial deliverability equations,principally analyzes and practically verifies the effect caused by previous operations on productivity forecast.Study results show: coefficients of the binomial deliverability equations will be changed due to direct application of averaged gas rate;the coefficient B decreases while the calculated open-flow capacity increases with the increase of the gas rate(the open-flow capacity increases by about 1.5% when gas rate increases by 1%);and simple pressure averaging can cause abnormal characteristic curves of the binomial equations.