International Journal of Polymer Science

Volume 2018, Article ID 1067902, 7 pages

https://doi.org/10.1155/2018/1067902

## Research of Flow Field of Alkaline/Surfactant/Polymer Solution in the Annular Depressurization Slot by PIV Experiment

^{1}College of Petroleum Engineering, Northeast Petroleum University, China^{2}Post-Doctoral Scientific Research Station, Daqing Oilfield Company, China^{3}Hangzhou Urban & Rural Construction Design Institute Limited Company, China^{4}Aramco Asia, China

Correspondence should be addressed to Bin Huang; moc.361@a205nibgnauh

Received 27 July 2017; Revised 14 November 2017; Accepted 13 September 2018; Published 3 December 2018

Academic Editor: Domenico Acierno

Copyright © 2018 Cheng Fu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### Abstract

In order to study the flow field changes of ASP (alkaline/surfactant/polymer) solutions with different molecular weights and flow rates when flowing through the annular depressurization slot in the laboratory, the annulus pipeline model was designed based on the principle of similarity. The particle image velocimetry (PIV) system was used to continuously capture the transient images when the ASP solution flows in the model under different experimental conditions. Tecplot software was used to analyze and process the nephrograms of the velocity distribution of ASP solution when flowing through the partially pressured injection tool with different depressurization slots. The experimental results showed that the vortex occurred at the bottom of the depressurization slots; the greater the flow rate, the closer the vortex center to the outer wall; higher molecular weight of the polymer in the ASP solution caused larger velocity gradient towards the wall. The number of the slots has no significant effect on the position of the vortex. This experiment provides a new research method for the velocity distribution of the internal flow field in the partially pressured injection tool.

#### 1. Introduction

In past years, the application of the partially pressured injection tool used in Indonesia Limau oil has been limited due to a lack of sufficient theoretical basis for the runner shape design. This also restricted the design and manufacture of pressure relief groove. Therefore, studying the internal flow field of the partially pressured injection tool is necessary [1, 2].

Compared with the point measurement by Laser Doppler Velocimetry (LDV), PIV can perform direct surface measurements for the flow field to ensure the accuracy of the measurement and certain spatial resolution. Therefore, PIV is suitable to analyze the change of the flow field. PIV has two distinct characteristics: it does not disturb the flow field and the entire picture of the flow field can be simultaneously obtained through instantaneous flow-velocity vector. It is a powerful tool to study complex flow structures such as eddy currents and turbulence [3–5].

Feng et al. [6] simulated the flow process and flow field of the polymer solution through the layered injector and found that the flow of the polymer in the layered injector was relatively stable. This could be a benefit for preventing the mechanical shearing and reducing the viscosity loss of the polymer solution during the polymer injection process. Meng et al. [7] used the software PHOENICS to calculate the flow field in the layered injector and found that the shape of the annular channel of the layered injector had great influence on the flow field characteristics. Cai et al. [8] analyzed the flow field of the ASP solution in the eccentric injector by the commercial software Fluent. The simulation results showed that the velocity and pressure of the flow were periodic, and each period was similar. Due to a lack of experimental methods, the optimization of the structure of the partially pressured injection tool and the flow-field distribution in the depressurization slot of the injection tool were mainly simulated and analyzed by using Fluent numerical simulation software. Our research is the first trial to study the flow field of the injection tool by experimental method.

In this paper, the interior flow field of the injection tool is studied by laboratory experiments. A set of experimental models of partially pressured injection tools for PIV system are designed by using the principle of similarity [9–11]. Three experiments with different flow rate, component, and number of slots were performed and compared with the experimental model [12]. A high-speed camera was used to capture the images of the flow field within the partially pressured injection tool. Different postprocessing had been used to handle the experimental data by Tecplot software. The flow field conditions within the partially pressured injection tool had been determined under different experimental conditions. The influence regulations for the inner flow field of the polymer with the weak base have been obtained for three element solutions with different molecular weight, flow rate, and number of slots. It will help provide guidance for the design of the depressurizing channel in the future.

#### 2. The Principle of Similarity

##### 2.1. Similar Proportions

###### 2.1.1. Geometric Similarity

The shape of the model used in this experiment is exactly the same as the prototype of the partially pressured injection tool. In order for good quality observations, the model was enlarged to a certain proportion [13]. Assuming that the length of the depressurization slot in the model is *l _{m}*, the diameter is

*D*, and the length of the actual depressurization slot of the partially pressured injection tool is

_{m}*l*, the diameter is

_{p}*D*.

_{p}The proportion of geometric similarity is expressed as

###### 2.1.2. Kinematic Similarity

Under similar geometrical conditions, the scale of time can be described as
and the scale of velocity can be described as
where *v* is the average velocity when the solution flows through the depressurization slot; *t* is the time for the solution to pass through the length *l* of the depressurization slot.

###### 2.1.3. Dynamic Similarity

The scale of pressure can be described as

The solution used in the experiment is the same as that used in the field. It means that *ρ _{p}* is equal to

*ρ*. Therefore, the following formulation can be obtained:

_{m}##### 2.2. Criterion of Similarity

Since the viscous force plays an important role in this experiment, the criterion of similarity for viscous force is used to judge similar situations. The similitude criterion of the viscous force is the Reynolds number. Therefore, if the Reynolds number of the prototype is equal to the model, the dynamic similarity can be achieved.

The generalized Reynolds number of non-Newtonian fluid can be described as

The equation can be concluded by calculating as follows:
where the value of *n* is equal to the value of , namely,

The experiment needs to

Because the cross section of the model is a concentric circle and the hydraulic diameter of the model is the characteristic length of the model. The characteristic length can be described as follows:

Where *χ* is the wetted perimeter, is the cross section area of passage, *R* is the outer radius of the flow section, and is the inner radius of the flow section.

Since , the following are obtained:

When the ratio of the flow rate of the experimental model vs. the field condition reaches the above conditions, the dynamic similarity can be considered.

##### 2.3. Streamlined Partially Pressured Injection Tool

The main objective of the simulation research is to optimize the internal structure of the depressurizing channel in the streamlined partially pressured injection tool. The structure of streamlined-separating injection tool is shown in Figure 1, and the modified shuttle rod partially pressured injection tool is shown in Figure 2.