热采双管水平井改善稠油油藏加热效果研究

平行双管与同心管注汽技术是为解决水平段吸汽剖面不均而提出来的稠油水平井完井新方法。采用稳态实验方法,进行了多孔介质中稠油的渗流特征实验。在获取了零启动压力梯度拐点温度的基础上,研究了水平井双管分段注采对水平段吸汽剖面的影响。结果显示,实验测得的两种稠油油样在油藏条件下的零启动压力梯度的拐点温度分别为72℃,65℃。储层与流体物性参数、注汽方式以及注汽参数等均对双管注汽开发效果有所影响,其中水平段的沿程非均质性、注汽方式、周期注气量、蒸汽干度和盲管段长度影响较大。当盲管段长度较小时,纵向加热半径也较小,此时A、B两段注入的蒸汽发生窜通的可能性较大。

Improving the heating results of dual-injection in thermal horizontal wells in heavy oil reservoirs

On account of the reservoir heterogeneity and variable-mass-rate flow in horizontal segment, the problems of poor steam absorption and sweep efficiency are encountered in the thermal horizontal wells. The EOR technology of dual-injection in thermal horizontal wells is proposed to solve this problem of low heating efficiency. Using the steady-state method, the flow characterization of heavy oils in porous media is experimentally conducted. From the results, the temperature breakpoints of heavy oil are obtained, and the influence of dual-injection on steam absorption section in horizontal wells is discussed. The obtained results show that the influence of several factors (including reservoir or fluid physical properties, steam injection method, cyclic steam injection volume, steam quality and unperforated interval) are significantly. In order to delay the occurrence of steam breakthrough between the two steam injection intervals, the length of unperforated interval should exceed 20m.