井筒管流、喷嘴节流及地层渗流耦合的聚驱分注井分层流量调配方法——以大庆油田为例

Coupled conduit flow-throttled flow-seepage flow separate-layer injection rate allocation method for polymer injection wells: a case study from Daqing oilfield

在聚合物的注入过程中,聚合物从井口注入后在油管内流动,利用非牛顿流体力学原理建立垂向管流沿程压力损失方程。当聚合物溶液流过喷嘴时损失一部分压力与粘度。通过室内的聚合物溶液过喷嘴实验,得出了喷嘴的长径比(L/D1)及摩阻系数λ与雷诺数Re之间的关系。应用纲量分析的方法,建立了聚合物流过喷嘴后的压力损失Δp和粘度损失Δη的基本方程。结合实验数据,利用SAS软件进行回归分析,分别得到了压降及粘降关联公式。聚合物溶液流过喷嘴后进入地层,在聚合物溶液压力的作用下,聚合物溶液与岩石空隙的骨架相互挤压,聚合物的注入量也随时间逐渐降低。按照非牛顿流体在地层岩石中的渗流特点建立的单相非牛顿流体径向流的偏微分方程,结合大庆油田聚合物注入井的实际数据和前面的井筒管流、喷嘴节流产生的压力损失Δp和粘度损失Δη来束缚方程的边界条件,使用有限差分将方程离散,并应用软件求解,得出了聚合物注入压力、注入量与时间的关系,为聚合物分层配产提供了理论依据。

In the process of polymer flooding, polymer solution flows first through tubes in wellbore after injected from wellhead. A vertical conduit flow frictional pressure loss equation is set up according to the theory of non-Newtonian fluid mechanics. Usually, a part of pressure and viscosity will be lost when the polymer solution flows through a nozzle. The re- lationships of nozzle length to diameter ratio （L/D1 ）with friction coefficient（ A ）and Reynolds number （Re）can be estab- lished through experiment modeling the process of polymer solution flowing through nozzle. The basic equations of pres- sure lossAp and viscosity loss At/are developed by using dimension analysis method. In combination with the experimen- tal data, an incidence formula of pressure drawdown and dynamic viscosity loss can be built through regression analysis with SAS software. After polymer solution enters strata,it will squeeze the skeleton of rock under pressure of polymer so- lution and the injection rate will also decrease with time. Partial differential equations of single phase radial flow of non- Newtonian fluid is established according to the seepage characteristics of non-Newtonian flow. The equations are discrete by using the finite difference and solved by software with the boundary conditions of the equations constrained by the real data, pressure drawdown and dynamic viscosity loss caused by conduit flow and throttled flow. The relationships between injection pressure,injection rate and time are established, providing a theoretical basis for separate-layer polymer injection rate allocation.