水平井注汽启动阶段流动特性研究

Research on Heat and Mass Transfer Characteristics of Steam Injection Thermal Recovery by Horizontal Well in Star Stage

水平井技术已成为稠油油藏开采中的一项重要技术被广泛应用。在理论和数值研究中使用较多的井筒线源模型,假定水平井段湿蒸汽参数不变,没有考虑湿蒸汽在井筒内传热传质的变化对油藏吸汽的影响。为进一步完善注蒸汽模型,本文以筛管水平井为例,建立了井筒与储层数值模型,研究了注蒸汽采油启动阶段的油、水、汽三相在井筒和油藏中流动与传热规律,分析了井筒内积存原油对蒸汽推进的影响及湿蒸汽参数沿水平井段变化规律。结果表明:水平井段沿程热损失大,湿蒸汽热焓值从水平井跟端到趾端下降较快,造成跟端吸汽量高,趾端吸汽少甚至无法吸汽;井筒内积存原油影响蒸汽沿井筒轴向的扩散和热传递,加剧了油藏吸热的不均匀。

In recent years,Horizontal Well Technology（HWT） has been widely used in the development of heavy oil field.The well linear source model is widely used in modeling simulation and wet steam parameters in wellbore is assumed as constant without considering the impact of vapor and water parameters change to the steam injection.To promote steam injection model of horizontal well,taking sieve tube horizontal well as an example,the physical model was built in the first place.And then,based on Volume of Fraction（VOF） model,how the vapor-water-oil three-phase flows and transfers heat in reservoir and wellbore in startup phase was studied.In addition,how the vapor and water hindered by oil stockpile on advance process in steam injection string and casing tubing annulus was analyzed.Simulation results show that horizontal well belongs to variable mass flow system,there are large amount of heat loss along the horizontal wellbore,and heat enthalpy of wet steam from the heel to the toe rapidly decline,resulting in the heel-end of the reservoir take in much heat,however the toe-end got a few heat or even can＇t get;oil stockpile in steam injection string and casing tubing annulus hinder wet vapor diffusions,which exacerbated uneven of heat absorbing of the reservoir.