Three phase separation process
This case study was commissioned by BG Group in the UK to establish the feasibility and potential improvements to be gained by applying ADEX to offshore separation or oil, water and gas (three phase). The tests covered a wide range of operating conditions from widely ranging flow conditions to problematic pumps and valves, all situations which could be encountered offshore. The results were highly successful and ADEX was found to perform considerably better than rival methods. The separation strategy was to have primary control over levels and pressure at a particular set point while the pressure set point itself was adjusted to maximise production; in other words, maximising production flow was a primary control objective.
From the final results (shown below), the conclusion was that the strategy was feasible, given the enhanced control precision and process stability, which meant that production offshore could be increased by between 1% and 5%, representing a considerable increase in revenue at current oil prices.
A mix of crude, water and gas enters the first stage separator, at which point phases separate out due to differences in density. Note also that the levels of water, crude and pressure are controlled independently in the separator.
Here can be seen four aspects of the application:
- The result of increasing the flow rate of the mix entering the separator.
- The pressure controlled to follow the set point
(PID). - The pressure set point adjusted accordingly (ADEX control).
- Maintaining the oil control valve at the maximum permitted.
Note the improvement provided by ADEX.
