渤海“三高”气井环空早期圈闭压力预测

针对渤海"三高"（高温、高压、高酸气含量）气井生产早期环空圈闭压力过大严重威胁井筒安全、现有计算模型不能满足"三高"气井圈闭压力计算需要进而影响井筒完整性管理的问题，为准确预测"三高"气井的圈闭压力，基于漂移模型、动量守恒、能量守恒、井筒传热学、平面应变力学方程、气体状态方程以及管柱力学相关理论，建立了"三高"气井井筒温度、压力耦合预测模型以及气液两相圈闭压力迭代模型，实现了"三高"气井高温、高压、产水和非烃气体等实际工况下的气液两相圈闭压力计算，并解决了现有计算模型适用性差以及迭代不收敛的问题。研究结果表明：所建温度、压力耦合预测模型误差约为5%；相较于已有模型，所建模型计算结果更接近现场实际情况，误差在7.5%以下，高产工况下准确度更高；分析得到了"三高"气井不同因素对圈闭压力的影响规律，进行定量化敏感性分析，并以此为依据从工程角度提出了环空圈闭压力的控制措施。其中，环空预留5%~7%气柱能有效降低圈闭压力。

Prediction of early annular trap pressure of three-high gas wells in Bohai Sea

In view of the excessive annular trap pressure in the early production of "three-high" (high temperature, high pressure and high acid gas content) gas wells in Bohai Sea that seriously threatens wellbore safety, the existing calculation model cannot meet the needs of calculating the trap pressure of three-high gas wells, thus affecting wellbore integrity management. In order to accurately predict the trap pressure of three-high gas wells, a coupling prediction model for the wellbore temperature and pressure of three-high gas wells and an iterative model of gas-liquid two phase trap pressure were established based on drift model, momentum conservation, energy conservation, wellbore heat transfer theory, plane strain mechanics equation, gas state equation and theories related to pipe string mechanics. On this basis, this paper completes the calculation of gas-liquid two phase trap pressure under the actual working conditions of high temperature, high pressure, water production and non-hydrocarbon gas in three-high gas wells, and solves the problems of poor applicability of the existing calculation models and non-convergence of iteration. The results show that the error of the newly established temperature and pressure coupling prediction model is about 5%; compared with the existing models, the calculated results of the newly established model are more consistent with the actual situation on site, with an error below 7.5%, and the accuracy is higher under high-yield conditions; the influential laws of different factors on the trap pressure in three-high gas wells are obtained by analysis, quantitative sensitivity analysis is also carried out and on this basis, the control measures of annulus trap pressure are put forward from the perspective of engineering, among which 5%~7% gas column reserved in annular space can effectively reduce the trap pressure.