同井注水采油工艺数值模拟及参数优化

Numerical simulation and parameter optimization for water injection and oil production technology in the same well

为掌握分层注水采油井井筒内流体温度分布规律,以井底油温和井口注水温度作为边界条件建立了井筒内流体温度计算模型,以注入流量或温度最低为目标,以产液温度不低于防蜡温度为约束条件,建立了工艺参数优化模型,编写了相应的计算程序。对某采注井进行了模拟,结果表明,对于给定注水工况,产液井口温度随产液量增加而降低;随注水温度升高或注水量增加而上升。对于给定注入水温,优化所得最小注水量下产液沿程温度均不低于防蜡温度,对于给定注入流量,亦满足上述结论。结果保证了工艺参数在避免结蜡的前提下大大降低注水加热成本,对稠油经济开采具有重要指导意义。

In order to obtain the fluid temperature distribution in the injection-production wellbore to implement the optimization of the injection-production technology,the mathematical model for calculating the fluid temperature in the wellbore is established taking bottomhole oil temperature and wellhead injection water temperature as boundary conditions. The injection-production technology parameter optimization model is also established taking water injection flow rate or water injection temperature minimizing as objective and taking the produced liquid temperature not lower than wax precipitation temperature as constraint condition,and the corresponding program is written. The simulation result of a injection-production well show that,given water injection temperature and flow rate,wellhead produced fluid temperature decreases with increasing of produced fluid flow rate; given water injection flow rate and produced fluid flow rate,wellhead produced fluid temperature increases with increasing of water injection temperature; given produced fluid flow rate and water injection temperature,wellhead produced fluid temperature increases with increasing of water injection flow rate. Given water injection temperature( water injection flow rate),the produced fluid temperature in wellbore is not lower than wax precipitation temperature under the minimum water injection flow rate( minimum water injection temperature) obtained by optimization,the optimized technological parameters ensure that there is not wax precipitation and greatly reduce the cost of heating water injection. The study is of impor-tant guiding significance to the economic exploitation of heavy oil.