The Fram West field is developed by two subsea templates tied back to the Troll C platform, located in the North Sea. Fram West has two parallel topside choke valves that receive the production fluids from subsea wells, where the Typhoon Valve System replaced one of the chokes. The Fram West and Fram East production pipelines are combined downstream of the choke valves, and are processed in Fram separator as shown in Figure 2
. The gas, oil and water from this separator are further treated by the Troll C process facilities.
Figure 2. – Schematic of the Fram process layout. (Click to enlarge figure)
For the performance test of the Typhoon Valve System, the conventional choke was closed and all production flow routed through the Typhoon Valve System. After sampling and collection of test data, the Typhoon Valve System was closed and the conventional choke valve opened, and new performance data collected.
The process conditions were relatively stable during the performance test, and the fluids from the Fram field had high gas content and low water cut during the test period. The differential pressure across the chokes was approximately 15 to 20 bar. Minor slugging was observed during the test period.
Fluid samples obtained downstream the choke valves were analyzed in terms of oil-in-water (OiW) and water-in-oil (WiO) contents. Measurements of the oil-in-water content are shown in Figure 3
. The results reveal systematic improvement of the water quality with an average of 60% improvement for the Typhoon Valve System.
Figure 3. – Results from OiW measurements downstream the choke valves. (Click to enlarge figure)
The WiO concentration measurements showed that both the conventional choke valve and the Typhoon Valve System slightly reduced the oil quality. It is worth noting that the oil upstream choke valves contained very little dispersed water. Average WiO concentration downstream both valves was still very low and within the maximum WiO specification for pipeline transport of 0.5%.
Noise and vibration
The tested choke valves are located in an open module on the edge of the platform. Therefore, considerable amount of background noise was observed during the noise measurements. The general observation was that the both valves produced very little noise, and could not be heard over the background noise. Vibration measurements showed no difference between the two valves.