Designing and Validating a Screw Pump for Multiphase Down-Well Conditions

The challenge

The pump had to handle multiphase fluids reliably under conditions that are difficult to replicate and model without purpose-built tools. Performance prediction, bearing load characterisation and practical validation all had to be achievable under loading and assembly conditions representative of actual deployment in a 12-metre module stack in an incredible challenging environment, not just in a laboratory setting.

PTL’s role

PTL contributed to pump profile development and led the design of the wider module stack, covering the gearbox, centraliser, compensator, electric motor and telemetry module. In-house software was developed to generate rotor profiles and predict pump performance and bearing loads, giving the programme a proprietary tool for performance analysis, where existing tools were not commercially available. Test rig specification and independent hardware testing under equivalent down-well loading followed, closing the loop between analytical and measured behaviour.

Why it mattered

Generic tools did not handle the intricacies of the pump geometry well, particularly for multiphase conditions. Developing in-house rotor profile software was a deliberate choice. It gave the programme a direct connection between the screw geometry, the predicted performance and the bearing loads. Generic tools were found to handle the intricacies of the pump geometry poorly, particularly for multiphase conditions. For a pump intended for harsh service environments, that level of analytical rigour is what is required to produce a credible design.