异常高压气藏采气速度与稳产期定量关系——以阿姆河右岸B-P气田为例

Quantitative relationship between gas recovery rate and stable production period of abnormally high pressure gas reservoirs:a case study of B-P gas field on the right bank of the Amu Darya

针对阿姆河右岸B区中部异常高压气藏生产动态预测难度大的问题,从气藏实际出发,以物质平衡方程和气井产能公式为基础,结合气藏工程分析及数值模拟方法,建立了异常高压气藏稳产期预测模型。通过分析气藏开发过程,研究了地层流体特征参数随气藏压力下降的变化规律,确定了气藏压力特征值,将异常高压气藏的开发过程划分为高压期与常压期两个阶段,并采用分段函数对预测模型进行求解,得出了不同阶段采气速度与稳产期末采出程度的定量关系。实现了不同采气速度情况下气藏稳产期的快速预测。将该方法应用于B-P气藏并与数模结果相互验证,稳产期预测的绝对误差小于2%,满足工程计算精度要求。同时,采用该定量关系也可对异常高压气藏递减期产量进行预测。

A great difficulty exists in predicting the production performance of abnormally high pressure gas reservoirs in the middle section of Region B on the right bank of the Amu Darya.According to the actual situation of reservoirs,a model was established based on material balance equation and gas-well productivity equation in combination with gas reservoir engineering analysis and numerical stimulation method,so as to predict the stable production period of abnormally high pressure gas reservoirs.Through analyzing gas-reservoir development process,the change laws of formation fluid characteristic parameters with the decline of gas-reservoir pressure were studied to determine the eigenvalue of gas-reservoir pressure.The development of abnormally high pressure gas reservoir was divided into two phases,i.e.,high pressure stage and constant pressure stage.Moreover,piecewise function was used for solution of the prediction model,so as to obtain the quantitative relationship between gas recovery rate in different stages and the recovery degree at the end of stable production period.On this basis,rapid prediction of stable production period was achieved in the case of different gas recovery rates.This method was applied to B-P gas reservoir for mutual,and validated with numerical stimulation results.The absolute error of prediction on stable production period was less than2%,able to meet the requirement of engineering calculation accuracy.Meanwhile,this equation is also available in output prediction during the depletion period of abnormally high pressure gas reservoirs.