井筒内超临界多元热流体注入过程的数值模拟

在稠油热采过程中,提高注入工质的流动参数可显著增加采收率。为评价超临界多元热流体注入井筒后的流动传热特性,建立了相应的计算模型,得到了井底温度、压力与沿程热损失随注入流量、井口温度及井口压力的变化规律,并与注入超临界蒸汽情况下的流动传热规律进行了比较。结果表明,井底参数与注入流量呈单调关系;井底压力与井口温度、压力亦呈单调关系;而其他井口、井底参数的组合呈现出复杂关系。相同井口压力条件下,为使井底参数达到超临界状态,超临界多元热流体的井口温度和注入量高于注入超临界蒸汽的情况。适当选取较低的井口压力,可以减少热损失,提高经济性。所得结果可为注入工质参数的选取提供参考,进而为海洋稠油开发中的能源与动力保障的研究及设计明确需求。

Numerical Simulation of Supercritical Multi-component Heat Fluid Injected into a Wellbore

For the exploitation of viscous oil with thermal methods, further enhancement of recovery efficiency would be achieved by raising the flow parameters of the fluid injected into the wellbore. A calculation model was established in order to evaluate the flow and heat transfer of supercritical multi-component heat fluid injected into a wellbore. The bottom parameters (temperature and pressure) and the thermal loss along the wellbore versus the inlet parameters (flow rate, temperature and pressure) were calculated; and the results were also compared with those under the circumstance of the injection of supercritical steam (water). The results show a monotonic relation between the flow parameters at the wellbore bottom and the injection rate; and the pressure at the wellbore bottom also changes monotonously with the inlet temperature and pressure. The rest pairs of inlet and bottom parameters exhibit more complex relationship. To ensure the supercritical condition at the wellbore bottom, the injection rate and the inlet temperature of supercritical multi-component heat fluid must be higher than those of supercritical steam at the same inlet pressure. Economic performance can be improved through reducing the thermal loss by selecting lower but appropriate inlet pressure. The selection of fluid parameters for the thermal exploitation of viscous oil would benefit from this work; and then, the requirements could also be determined for the study and design of energy and power supply for the exploitation of offshore viscous oil.