基于Waha 双流体模型修正的UGS环空带压异常物理特征

Abnormal physical characteristics of UGS annular pressure based on improved Waha two-fluid model

关键词:  Waha双流体模型  地下储气库  环空压力  力学分析

Key words:  Waha two-fluid model  underground gas storage  annulus pressure  mechanical analysis

摘要:

为探究储气库(UGS)环空带压异常物理特征,考虑UGS井筒结构和传热特点,建立基于Waha 双流体模型修正的UGS力学分析方法。通过有限元软件模拟研究管柱泄漏后A-环空内气液两相流动特性。采用过冷减压试验和数值计算对UGS力学分析方法进行对比研究,并分析储库产量、径向面积和气液比等因素对环空带压的影响。以UGS-Q5井带压异常数据为例,通过相对误差分析验证方法的可行性。结果表明:泄漏气在A-环空内发生环状流动,井筒垂直结构有利于气体流动;在持续注入过程中,井筒泄漏导致油套环空带压增长趋势明显,并随着储库产量、径向面积和气液比增加而不断增加;建立的UGS环空带压异常物理特征分析模型具有较好的计算精度和工程实用性,能满足实际工程的计算需求。

Abstract:

In order to explore the abnormal physical characteristics of the annulus pressure in the gas storage (UGS), considering the UGS wellbore structure and heat transfer characteristics, a UGS mechanical analysis method based on the Waha two-fluid model correction were established. The gas-liquid two-phase flow characteristics in the A-annular after leakage of the column were studied by mean of the finite element software. The UGS mechanical analysis method was compared with the supercooling decompression experiment and numerical calculation, and the effects of reservoir output, radial area and gas-liquid ratio on the annulus pressure were analyzed. Taking the abnormal data of the UGS-Q5 well pressure as an example, the feasibility of the method was verified by the relative error analysis. The results show that the leakage gas flows in the A-annular, and the vertical structure of the wellbore is beneficial to the gas flow. During the continuous injection process, the wellbore leakage causes the oil ring annulus pressure to increase obviously, which also increases with the increase of the reservoir output, radial area and gas-liquid ratio persistently. The abnormal physical characteristics model of the annulus pressure in the gas storage established has a good accuracy and engineering application, which can meet the calculation requirements of actual engineering.