油砂蒸汽辅助重力泄油中汽液界面运移数学模型及规律分析

油砂SAGD过程实施蒸汽捕集控制的目的是为了在生产井上方形成一定高度的汽液界面,预防蒸汽突破的发生,提高热量利用效率。然而,现场操作中汽液界面位置并不能直接监测,只能通过监测注采井间温度差(subcool)进行间接估测。为了准确预测蒸汽腔汽液界面运移位置,将蒸汽腔内液池垂向剖面形状简化为“扇形”,根据流体渗流理论建立了汽液界面高度随subcool、注采压差和产液速度变化的数学模型,通过数值模拟证实其可靠性,并分析其运移规律。该模型结合动态监测资料和生产动态数据实现了汽液界面运移位置快速预测,可为现场技术人员准确判断汽液界面运移位置提供重要手段。

Mathematical Model and Moving Law for Steam-liquid Level below Steam Chamber in Oil Sands SAGD Process

The aim of steam trap control in SAGD process is to maintain certain steam-liquid level above producer, prevent steam breakthrough into the lower producer and improve heat energy efficiency. Nevertheless, it is almost impossible to monitor this liquid level, but to indirectly estimate steam-liquid level through monitoring subcool temperature difference between horizontal injector and producer. In order to accurately predict the height of steam-liquid level, a 2-dimensional steady state mathematical model reflecting the relationship of steam-liquid level, subcool temperature difference, pressure difference and liquid production rate was established, based on the assumption of simplification the shape of liquid pool into sector, which can be gained from earlier SAGD experiment conducted by Butler. Then, the theoretical model was confirmed a reasonably good approximation of steam-liquid level prediction by numerical simulation. Moreover, the moving law for steam-liquid level was analyzed under certain conditions of purified gravity drainage or certain pressure difference. Combined with dynamic monitoring and production performance data, this model can provide technicians_San important tool for predicting steam-liquid level location quickly and accurately.