## 4 Experimental Results and Discussion
### Comparative Characteristics of Temperature Field  
(1) The mechanism of electric heating in the injection phase  
Figure 4 displays the temperature profile at the end of the second cycle steam injection. From Figure 4, steam preferentially entered the oil layer from the heel and toe of the horizontal well, so the temperature at both ends (average 240 \({}^{\circ}\)C) was significantly higher than in the middle of the horizontal well (average 210 \({}^{\circ}\)C) during the conventional CSS process. The isothermal heating cable along the horizontal well heated the wellbore, which significantly improved the uniformity of heating in the horizontal section and the whole horizontal well reached 240 \({}^{\circ}\)C in the process of E-CSS. The electric heating effectively improved the steam temperature and dryness in the wellbore and the specific heat capacity and action range of steam were expanded. The high temperature area at the end of E-CSS is obviously larger than that of conventional CSS. (2) The mechanism of electric heating in the soaking phase  
Figure 5 displays the comparison of the temperature field at the end of the second cycle soaking phase. From Figure 5, the temperature near the wellbore area in the conventional CSS soaking phase continued to decline due to steam and thermal diffusion; and the temperature fell to an average of 140 \({}^{\circ}\)C. Due to the continuous heating and thermal compensation of the electric heater in the soaking stage, the temperature near the wellbore area dropped slowly in E-CSS; the temperature of the heel and toe tip of the horizontal section was continuously maintained at 240 \({}^{\circ}\)C, except that the middle temperature of the horizontal section dropped from 240 \({}^{\circ}\)C to 210 \({}^{\circ}\)C at the time of stopping the injection of steam. Due to the effect of thermal diffusion, the temperature from the well was also significantly higher than in the conventional CSS. The oil layer gained the continuous thermal compensation from electric heating in the soaking phase, which transferred heat to the deep part of the oil layer as well, relying on the temperature gradient. Figure 4: Temperature profile at the end of the second cycle steam injection. (3) The mechanism of electric heating in the production phase  
Figure 6 displays the comparison of the temperature field at the middle of the second cycle production phase. From Figure 6, the comparison of the temperature field in the middle of production shows that, during the conventional CSS process, the temperature of the oil layer continued to decline to about 78 \({}^{\circ}\)C with the continuous heat diffusion of the oil layer and the heat that was taken away by the output fluid. However, the temperature of the oil layer near the wellbore area continued to be kept above 140 \({}^{\circ}\)C in E-CSS. This was because the continuous thermal compensation of the electric heater to the oil layer though the produced fluid drove a lot of heat away. Figure 5: The comparison of the temperature field at the end of the second cycle soaking phase. Figure 6: The comparison of the temperature field at the middle of the second cycle production phase. Figure 7 shows the comparison of the temperature field at the end of the second cycle production phase. From Figure 7, it can be seen that the continuous thermal diffusion of the conventional CSS and the output heat loss of the conventional CSS had further reduced the oil layer temperature to about 70 \({}^{\circ}\)C. In the second half of the E-CSS production, due to the decrease in the output fluid speed, the heat output decreased, and the continuous thermal compensation of electric heating increased the oil layer temperature; the range of temperature (140 \({}^{\circ}\)C) was further expanded near the wellbore area.