The test program included the following modes, shown as Test No. on the x-axis in Fig. 1:
- Reduced emulsion breaker injection rate
- Reduced separator water level (from approximately 13 to 9 minutes retention time)
- Reduced separator oil level (from approximately 15 to 8 minutes retention time)
- Increased pressure drop across the valve
Normal conditions with normal emulsion breaker injection rate
The tests were performed at demanding conditions:
- Challenging water cut: 50% (dispersed phase and continuous phase were unstable)
- High differential pressure across the choke: 70 to 90 bar
- High gas content: 94% gas volume fraction upstream the chokes
- Long separator retention time: 10 - 15 minutes
During the test program, the well had around 50% water cut. Such flow conditions commonly present separation challenges as the flow alternates between being oil continuous and water continuous. The main parameter was the water quality (OiW concentration) at the outlet of the test separator, seen in Figure 1
. The average reduction in the OiW concentration at the water outlet of the separator was around 45% when operating with the low shear Typhoon Valve System, compared to that of the conventional choke valve. Measured WiO concentrations at the oil outlet of the separator showed an average improvement of 35%.
Especially interesting results were obtained at point 5 in the test program. At the increased pressure drop, the Typhoon Valve System was operating with an opening of less than 10%. At this small opening, there was insufficient momentum to drive the cyclonic flow in the valve. The complete pressure drop was instead taken over the cage, which is how the pressure drop is generated in a conventional valve design. It was therefore reassuring to see that the test showed similar oil-in-water content for both the Typhoon and the conventional choke at this point. Due to the abnormal valve operation, these results are not included when calculating the average improvement. These results prove, however, that during normal operation, when there is sufficient momentum to drive the cyclonic flow in the Typhoon Valve System, the low shear valve reduces shear forces, and improves oil and water separation.