水平井蒸汽吞吐热采过程中水平段加热范围计算模型

Calculating models for heating area of horizontal wellbore in steam stimulation

对于稠油水平井的产能评价和动态预测,注蒸汽吞吐生产过程中水平段的加热范围至关重要。由于油藏中水平井水平段长度比直井中直井段长得多,蒸汽的压力、温度和干度沿着水平段分布不均匀;根据水平井变质量流的思想,用动量定理和能量守恒定理建立蒸汽沿水平段的压力、温度和干度分布计算模型;同时根据传热学等有关学科知识,考虑水平井中水平段加热过程和机理不同于直井的加热过程和机理,建立了水平井注蒸汽吞吐加热范围计算模型。根据辽河油田冷42块油藏基本参数,用所建立的模型对水平段加热范围进行了计算,对计算结果进行的研究表明:蒸汽压力、温度、干度、加热范围沿水平段不是均匀分布的,第一临界时间、第二临界时间的概念反映了蒸汽在油层的运移过程。

During the steam stimulation with horizontal wells in heavy oil reservoirs, the heating area of a horizontal wellbore is very important to the productivity evaluation and performance forecast. The steam pressure, temperature and quality are not even along the horizontal wellbore for the horizontal wellbore in the reservoir is much longer than vertical well. Based on the variable-mass flow theory, the distributing models of the steam pressure, temperature and quality in the horizontal wellbore are presented by use of the momentum theorem and energy conservation theorem. The calculating models of heating areas along horizontal wellbores are derived according to the fact that horizontal wellbores are different from vertical wellbores in terms of the heating process and mechanism. The heating area in the horizontal wellbore is calculated with the presented models by the geologic parameters of Block Leng 42 in Liaohe Oilfield. The results show that the steam pressure, temperature, quality and heating area are not even along the horizontal wellbore and that the concepts of the first and second critical time reflects the flow performance of steam in the reservoir.