AkerKværner’s MultiBooster™ subsea pump is to be installed on Eni UK’s Balmoral field in a pilot project that represents an important step towards commercial application. The project will provide an opportunity for the pump to demonstrate increased production from a field in its late life.

The Balmoral prototype is a marinisation of the market-leading Bornemann multiphase twinscrew pump of which more than 220 have been sold for onshore application over the last 13 years. The pump is due to be installed on the field in a water depth of 140 metres in the third quarter of 2004, and it will be located on the subsea manifold that gathers production from the Balmoral wells. In a mature field such as Balmoral, the effect of pumping is to relieve the backpressure and thereby increase the flow, thus improving the field’s recovery factor. The pilot project includes an extensive condition monitoring programme that is expected to provide valuable feedback for enhancing the reliability of the product.

MultiBooster™ module

Subsea multiphase pumping has been identified as a key technology for oil and gas production. It has the potential for boosting tail-end production and also has the ability to raise the distance over which fields developed with subsea facilities can be tied back to host infrastructure. Tie-backs up to 18 to 20 kilometres without subsea transformers are within reach, and further development may make 100-kilometre step-outs possible in the future.

The introduction of subsea multiphase pumping can bring great benefits to the offshore industry by helping to make it economic to develop fields which are currently considered uncommercial. After carrying out a lengthy development programme AkerKværner welcomes the opportunity to put the MultiBooster™ to work in a live situation.

Artist conception of the MultiBooster™ module at the Balmoral field

Demo 2000 Backing
In recognition of the technology’s significant potential, the development project was included in the Norwegian government’s Demo 2000 technology demonstration programme. The installation phase is headed by Eni UK and its partners, Talisman, Summit North Sea and Pentex oil and supported by Eni Norge, Shell Technology Norway, Norsk Hydro on behalf of the Fram licence, Total E&P Norge and Statoil.

Technical Specification
The MultiBooster™ consists of a twin-screw pump and oil-filled electric motor packaged as a modular system which can be easily adapted to template and manifold configurations. In addition to Bornemann, Kvaerner Oilfield Products was partnered in the development by Flender-Loher, which developed the electric oilfilled motor.

The Balmoral prototype pumping unit, which will weigh about 45 tonnes, will be installed on a prefabricated flow-base with the necessary piping and bypass valves.

The MultiBooster™ pump design provides high operational flexibility, covering all gas-liquid ratios including high tolerance for slug flow and sand. It has the ability to maintain the pressure-boosting specification independent of gas content at the pump inlet – in other words it can handle slug flow with gas void fractions from 0 to 100 percent gas. It can also handle the high water fractions typical of the wellstream in a field’s late-life phase – in the case of the Balmoral application, the water cut will be around 85 to 90 percent and rising.