静气柱压力数值计算方法及其应用

Numerical Calculation for Static Gas Pressure and its Application

井口最高稳定关井压力计算的准确与否直接关系着钻完井设计水平和施工安全性。在目前设计施工中其常采用近似公式和精确公式两种方法进行计算,其中近似公式在深井计算中误差较大,精确公式由于缺乏气体组分数据,在计算结果上也存在一定误差。为此,引入数值计算方法,建立了气体一维稳定管流压力计算模型;基于气井井口关井条件,形成了井筒内静气柱压力分布计算方法,并通过实例验证其实用性和正确性。

A calculated accuracy of static gas pressure in wellbore will affect directly the drilling and completion design.So far,there are two calculations of approximate formula and exact formula.A big error may be existed in deep-well by approximate formula calculation;a certain error may also be existed by exact formula calculation due to a shortage of gas component data, average temperature and compression factor.This paper presents a numerical method to calculate static gas pressure.In this method a calculation model of 1D stable tube flow pressure is established and a distribution of static gas pressure in wellbore is calculated under a shut-in pressure at wellhead.The numerical calculation has been applied to case study and can provide a technica guidance for drilling and completion design and operation.