稠油油藏水平井双管注采井筒内流体流动与传热规律研究

The horizontal well pair in SAGD process is always completed with dual tubing. The proper landing position of tubing, the steam injection ratio and the production ratio between the long and the short tubing are the key to realize the steam uniformly injected into the formation and the fluid evenly produced from the formation along the horizontal wellbore. However, there is a lack of an effective method to optimize them. The project aims to study the fluid flow and heat transmission in the horizontal steam injection and production wells completed with dual tubing. Firstly, the models to calculate the pressure and temperature in the long tubing and the annulus during the steam injection and fluid production period are developed respectively based on the fluid flow and heat transfer characteristics of the steam and the produced fluid in the long tubing and the annulus in the horizontal section. Secondly, the radial heat transfer model is presented considering the eccentric position of the long tubing and the heat transfer interference between the long tubing and the annulus. Thirdly, the effective method to solve these models are proposed. In the end, the wellbore pressure, temperature and heat losses distribution under different injection and production conditions are investigated, and the landing position of tubing, the steam injection ratio and the production ratio between the long and the short tubing are optimized. The results will provide theoretical basis for the development of horizontal SAGD well pair completed with dual tubing.

双管完井技术是双水平井SAGD开发常用的完井方式，合理设计管柱在水平段下入位置、长短管注汽比例和采液比例是实现双管双水平井SAGD均匀注汽和采液的关键，但目前缺乏与之对应的优化设计理论。本项目拟针对平行双管注采水平井筒内流体“双汇”和“双源”流动与传热及偏心长管与环空之间的传热干扰问题进行研究，探明双管注采水平井筒内压力场、温度场分布规律。具体内容包括：(1)基于注入蒸汽和采出液在水平段长管和环空内的流动及传热特点，建立双管注采水平井段长管和环空内压力、温度等参数计算模型；(2)考虑偏心位置及长管和环空之间的传热干扰，建立双管注采水平井筒内的径向传热计算模型；(3)研究上述模型的求解方法，形成双管注采水平井筒内流体流动与传热规律模拟计算方法；(4)研究双管注采过程中水平井筒内流体流动与传热规律，并优化管柱下入位置、长短管注汽比例和采液比例。研究成果可为双管双水平井SAGD开采提供理论指导。

双管完井技术是双水平井SAGD开发常用的完井方式，合理设计管柱在水平段下入位置、长短管注汽比例和采液比例是实现双管双水平井SAGD均匀注汽和采液的关键，但目前缺乏与之对应的优化设计理论。针对上述问题，项目组开展了大量研究，完成了预定任务，取得了预期成果，主要研究内容和成果如下：.（1）基于注入蒸汽在水平井段长管和环空内的流动特性，建立了双管注汽过程中水平井筒内流体流动与传热模型，并针对环空“双汇”问题，提出了细分微元和迭代的方法对其进行求解，形成双管注汽水平井筒内流体流动与传热规律模拟计算方法；同时，建立了稠油油藏储层内渗流与传热模型及双管注汽水平井井筒与储层耦合流动与传热模型，提出了相应的求解方法，为双管注汽水平井热采开发提供相对应的优化设计理论和方法。.（2）考虑油水混合物在水平井段长管和环空内的流动特性，建立了双管采液过程中水平井筒内流体流动与传热模型，并针对环空“双源”问题，提出了细分微元和迭代的方法对其进行求解，形成双管采液水平井筒内流体流动与传热规律模拟计算方法；同时，建立了双管采液水平井井筒与储层耦合流动与传热模型，提出了相应的求解方法，为双管采液水平井热采开发提供相对应的优化设计理论和方法。.（3）基于所建模型，研究了双管水平井蒸汽吞吐开发、SAGD循环预热和生产过程中井筒内流体流动与传热规律；分析了蒸汽注入参数、长短管注汽比例、管柱下入位置对水平井吸汽剖面和采液剖面的影响，并对其进行了优选。结果表明，双管注汽方式可提高注汽均匀性，有利于蒸汽腔的均匀发育，合理设置短管下入位置、长短管注汽比例可提高SAGD生产过程中注采剖面的均匀性，进而提高稠油油藏相对应的采收率。研究成果为双管水平井SAGD开采提供了理论指导。