# Experimental Study and Numerical Simulation of W/O Emulsion in Developing Heavy Oil Reservoirs
## 2 Experiments
### Emulsification Experiment
#### 2.1.2 Experiment Preparation  
In the experiment, crude oil and formation water were mixed in a predetermined proportion (water cut of emulsion), put into a beaker, and then heated to the temperature required by the experiment in a water bath, where the water bath provided a constant container temperature. The IKA.T18 digital display disperser was used to stir the mixture at a constant speed for a certain time to obtain the emulsion sample. The actual reservoir temperature of 60 \({}^{\circ}\)C, with a stirring speed of 4000 r/min, is equivalent to the shear force in reservoir formation, whereas, for a stirring time of 60 min with a water cut of 40%, the preparation of the emulsion and the actual reservoir emulsion particle size was similar; hence, these conditions were taken as the basic experimental conditions.  
1. **Stirring speed.** In order to study the effect of stirring speed on the stability of emulsion, other experimental conditions remained unchanged. The emulsion was prepared at stirring speeds of 200 r/min, 1000 r/min, 2000 r/min, 4000 r/min, 7000 r/min, and 12,500 r/min. The prepared emulsions were then allowed to stand for 40 days under the experimental conditions.
2. **Temperature.** In order to study the effect of temperature on the stability of the emulsion, the emulsions were prepared at 40 \({}^{\circ}\)C, 50 \({}^{\circ}\)C, 60 \({}^{\circ}\)C, 70 \({}^{\circ}\)C, 80 \({}^{\circ}\)C, and 90 \({}^{\circ}\)C. The prepared emulsions were then allowed to stand for 40 days under the experimental conditions.
3. **Water cut of emulsion.** In order to study the effect of water cut on the emulsion, the water cuts of the emulsions were set to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%. The prepared emulsions were then allowed to stand for 40 days under the experimental conditions.
4. **Mineralization degree.** Under the same experimental conditions, the formation water was made into water with different mineralization degrees using deionized water, i.e., 2000 mg/L, 4000 mg/L, 6000 mg/L, 8000 mg/L, and 10,000 mg/L, and then the emulsion with 40% water cut was prepared to study the effect of mineralization degree on the emulsion. The prepared emulsions were then allowed to stand for 40 days under the experimental conditions.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Density** & **Viscosity** & **Saturates** & **Aromatics** & **Resins** & **Asphaltenes** \\ \hline (20 \({}^{\circ}\)C) & (50 \({}^{\circ}\)C) & & & & \\ (g/cm\({}^{3}\)) & (mPa-s) & (wt.\%) & (wt.\%) & (wt.\%) & (wt.\%) \\ \hline
0.92 & 1231 & 27.48 & 29.26 & 36.46 & 6.8 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Properties and composition of crude oil.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Mineralization Degree (mg/L)** & \multicolumn{5}{c}{**Ion Concentration (mg/L)**} \\ \hline  & **K\({}^{\star}\)** & **Na\({}^{\star}\)** & **Mg\({}^{\star\star}\)** & **Ca\({}^{2\star}\)** & **HCO\({}_{3}\)\({}^{-}\)** & **Cl\({}^{-}\)** & **SO\({}_{4}\)\({}^{2}\)\({}^{-}\)** \\ \hline
7795.43 & 19.2 & 3404.7 & 13.6 & 52.2 & 314.45 & 3930.89 & 60.39 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Ion composition of formation water.  
* **pH value.** Under the condition of constant stirring speed and time, temperature, and water cut of the emulsion, the pH value of the formation water was changed using diluted hydrochloric acid solution and sodium bicarbonate solution. Then, it was used to prepare emulsions to study the effect of pH value on the stability of the emulsion. The prepared emulsions were then allowed to stand for 40 days under the experimental conditions.