对地层热阻计算方法的分析与改进

ANALYSIS AND IMPROVEMENT OF THE METHOD FOR EVALUATING THERMAL RESISTANCE OF FORMATION

研究了注蒸汽开采稠油工程设计所涉及的井筒传热问题中地层热阻的计算方法，指出了地层热阻计算方法的局限性，并提出了基于Ｄｕｈａｍｅｌ卷积定理的新的计算方法。通过应用两种方法对同一问题的计算对比，发现用Ｒａｍｅｙ方法计算出来的地层热阻较小，相应地计算出来的散热强度较大，井筒结构与地层交界面的温度较低。在注蒸汽的初期，应用改进的方法计算出来的交界面温度要比Ｒａｍｅｙ方法大得多。

The method for evaluating the thermal resistance of the formation outside the wellbore involved in heavy oil exploration with steam injection technique is studied and its limitations in practical use are shown. A revised method is proposed based on Duhamel's theorem as an alternative. Both methods are applied to a benchmark problem of the thermal resistance of the formation. It is shown that the classic method predicts lower thermal resistance of the formation, lower temperature at the interface between the wellbore and the formation and higher heat loss rate than those with the revised. At the beginning of steam injection, the revised method can give much higher interface temperature than the classic, and can provide thermal stress analysis for wellbore structure during steam injection with more reliable thermal data.