深水气井测试温压场耦合模型求解及实现

为求解深水气井测试温压场耦合模型,需优选气液两相流动模型,结合两相嘴流模型、两相持液率公式、两相产能方程,建立关于时间和空间的非稳态压降与传热模型差分方程组,并采用Newton-Raphson方法计算,实现对开井放喷瞬态过程的模拟。结果表明:①该方法真实再现了放喷过程中液位上升和地层产气等2个阶段;②预测井口参数与现场工况吻合,井口压力、温度平均误差小于5%,满足工程精度要求;③模拟结果再现了井筒内诱喷液及测试完井液动态过程,为合理制定测试设计提供依据;④高产能深水气井测试期间,应采用较大尺寸管柱及油嘴放喷,提高清井速度,防止冰堵。算例分析结果表明数学模型真实反映了深水气井测试放喷过程。该研究成果对深水气井测试方案设计及后续跟踪评价具有指导意义。

Solution and realization of coupled model of temperature and pressure field in deep water gas well testing

To seek the solution of the coupled model of temperature and pressure field in deep-water gas well testing,it is necessary to optimize the gas-liquid two-phase flow model. Based on two-phase nozzle flow model,twophase liquid holdup formula and two-phase productivity equation,the differential equations of unsteady pressure drop and heat transfer model about time and space were established,and Newton Raphson method was applied to realize the simulation of the transient process of blowout. The results show that:(1)The method can truly simulate the two stages of liquid level rising and formation gas production in blowout stage. (2)The predicted wellhead parameters are consistent with actual conditions,and the average error of wellhead pressure and temperature is less than 5%,which meets the engineering accuracy requirements.(3)The simulation results reconstructed the dynamic process of induced flow and test completion fluid blowout in wellbore, and can provide basis for reasonable test design.(4)For deep water gas wells with high productivity,larger size string and nozzle should be used to improve well cleaning speed and prevent ice blockage. The example analysis shows that the mathematical model truly reflects the test blowout process of deep water gas wells. The research results have certain guiding significance for the test scheme design and follow-up evaluation of deep water gas wells.