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储气库在建造和运行时,一方面溶腔内气体通过自然对流与周围盐层进行热交换,与周围盐层壁面形成不稳态导热温度场;另一方面连续注采循环,使腔内气体压力、温度发生变化,特别是在连续采气时,降压的焦耳—汤姆逊效应极易使井口气体压力和温度进入生成水化物的危险范围,因此动态确定盐穴储气库注采天然气时的热工特性变化十分必要。为此,根据热力学、传热学和流体力学理论,针对注采过程天然气在井筒流动和溶腔内传热过程的特点,将井筒、溶腔和周围盐层视为一个系统,提出了描述注采动态工程相互耦合的数学模型及其求解方法,并开发了相应的数值计算软件。该软件可预测盐穴地下储气库在连续注采气过程中,溶腔内及井筒顶、底部气体的压力和温度,并判断水化物形成的危险范围等。研究成果能对盐穴地下储气库的建造和技术特性做出预测分析,对其运行工况给予指导,并对注采气地面系统的优化设计提供理论分析依据。
During the construction and operation of the gas storage tank, on the one hand, the gas in the solution cavity exchanges heat with the surrounding salt water through natural convection and forms a steady temperature thermal field with the surrounding salt layer wall; on the other hand, Gas pressure and temperature change, especially in the continuous gas production, step-down Joule - Thomson effect is easy to make the wellhead gas pressure and temperature into the dangerous range of hydrate formation, so dynamic determination of salt and gas reservoir gas injection When the thermal characteristics of changes is necessary. Therefore, according to the thermodynamics, heat transfer and fluid mechanics theories, considering the characteristics of natural gas flowing in borehole and heat transfer in cavity, the wellbore, cavity and surrounding salt are regarded as one system. Mining dynamic engineering mutual coupling mathematical model and its solution method, and the development of the corresponding numerical calculation software. The software predicts the pressure and temperature of the gas in the cavity and the top and bottom of the well during the continuous injection of gas in the salt cavern underground gas storage and determines the dangerous range of formation of hydrates. The research results can predict and analyze the construction and technical characteristics of the salt caverns underground gas storage, give guidance to their operating conditions, and provide theoretical basis for the optimal design of gas injection ground systems.