压回法阶段压井数学模型与模拟分析

 根据压回法压井过程中气体压缩规律和气液两相流特性，提出了压回法压井过程可分为3 个阶段，并建立了考虑气体滑脱的阶段压井数学模型，用于压回法作业井底压力和套压变化规律的定量计算。压井参数敏感性模拟分析表明，压井排量越大，压井持续时间越短，产生的井底压力和套压越大；地层渗透率和渗透性地层厚度对压井第一阶段的井底压力和套压影响不大，但当高渗透或高厚度地层进入压井第二、第三阶段，随渗透率或地层厚度增加，压井产生的井底压力和套压减小，且降幅减缓。通过分析压井过程中井底压力和套压变化规律，绘制了压回法典型压井曲线模型。预测结果与实测数据对比表明：该数学模型具有较高的预测精度，能够为溢流压井方法的选择和压回法施工设计提供理论依据与指导。

Staged Well Killing Mathematical Model and Simulation for Bullheading

A bullheading process could be divided into three stages based on the gas compressibility law and the gas-liquid twophase flow law, and a mathematical model for each stage with consideration of the gas slippage is developed to quantitatively calculate the bottom pressure and the casing pressure under different well killing conditions. The simulations of the bullheading parameters show that, the kill time decreases and the bottom pressure and the casing pressure increase with the increase of the pump displacement; both the formation permeability and the permeable formation height have a little influence on the pressure in the first stage, but when the high permeable formation or the high height formation enters into the second and third stages, both the bottom pressure and the casing pressure decrease with the increase of the formation permeability or the formation height, and the change range becomes small. In addition, typical bullheading curves are obtained by analyzing the characteristics of the bottom pressure and the casing. The predicted model had a good agreement with the field test. This can provide a theoretical basis and guidance for the selection of killing methods and the design of bullheading.