This experiment originates from a field problem in a surface production facility (SPF). An oil company would like to identify a new chemical for their separation program. Because the incumbent program is not meeting the requirement of 0.5% BS&W exiting the facility resulting in the oil company paying a fine to the midstream company. Therefore, the company should use the bottle test to examine the performance of different chemicals at different temperatures and concentrations and to recommend the appropriate demulsifier at its working condition to meet the requirement. In the SPF, there are four well pads that produce into four flow lines. The four pads are called ZS1, ZS2, ZS3, and ZS4. ZS1 has a flow line that produces oil at the rate of 5,000 STB/D and water at the rate of 11,464 STB/D. ZS2 produces oil at 3,800 STB/D and water at 9,376 STB/D. ZS3 produces oil at 2,200 STB/D and water at 8,758 STB/D. ZS4 produces oil at 1,800 STB/D and water at 5,250 STB/D. All of these flow lines comingle with a demulsifier DMO to flow into a facility where treatment for the oil occurs. Figure 4 shows the flow diagram from the well pads to the