Page 94: of Offshore Engineer Magazine (May/Jun 2014)

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Subsea

The gas pressure pump The Rotoconverter now on-going, and they will be followed The aim, he says, is to offer a solu- The aim, he says, is to offer a solu- now on-going, and they will be followed is designed in the initial phase of the by the identi? cation of related technol- tion with a smaller footprint and higher tion with a smaller footprint and higher by the identi? cation of related technol- project.

? exibility, so that it can provide compres- ogy quali? cation programs. “On an active cooling system, we sion throughout the life of ? eld, adapt- The concept so far comprises three use forced convection cooling, with a ing to changes in the well stream and or modules, to allow for ? exibility, as ? eld small subsea pump to push the seawa- reservoir. requirements change. These will be cool- ter through the cooler. The design is “To do that we are developing a com- ing, compression and power modules. similar to Åsgard, but with additional pact subsea gas compression solution,” The wellstream will enter via an inlet, walls around the cooler and some baf? es

Gabelloni says. “Based on our quali? ed pass through an active cooling system, inside, to increase the heat exchange. The subsea compression system design, our then a compact scrubber, suitable for main bene? t is the increase in the heat target is to introduce new technologies, deep water and to minimize size, before transfer coef? cient, so we can reduce the in order to develop a compact option going through gas compression. weight and the size of the module,” he targeting medium to small size gas and Liquid removed by the scrubber will explained. Aker Solutions is currently in gas condensate ? elds. We are especially be boosted using a gas pressure pump, the concept selection phase on the cooler. looking also at long step-out distances utilizing two vessels, which are emptied

Gas pressure pump and deep water.” in turn utilizing gas coming from the

Aker Solutions started this develop- compressor. Power supply will be via a “The challenge with current systems is ment project nearly two years ago and is subsea transformer and Aker Solutions’ that the subsea pumps needed for the now in the concept selection and feasibil- RotoConverter, which is a frequency step liquid part of the well stream require the ity study phase. Proof-of-concept tests are up device to enable long distance AC use of barrier ? uid, with related tub- power transmission at ing, and, in the case of a long step-out, low-frequency. a subsea variable speed drive. Also, in

Three core elements some cases, when we have a small liquid being developed for the content in the wellstream, we need to project are the active re-circulate most of the ? ow to allow the cooler, the gas pres- pump to operate. sure pump, and the “To overcome these issues, we are

RotoConverter. developing a gas pressure pump. It uses pneumatic transport by leveraging the gas

Subsea cooler coming out of the gas compressor outlet.

Today’s subsea coolers We use two vessels, and a set of axial are designed based on valves, which control the gas from the what is known about a compressor. The two vessels are emptied ? eld during the design alternately. The bene? ts are that we do phase, Gabelloni says. not need barrier ? uids or any dedicated “They are passive power supply.” coolers, mostly with a The company has completed concept big footprint, and the selection and is moving into a proof-

A scaled-down Rotoconverter prototype. temperature control of-concept test phase, including sand

May 2014 | OE oedigital.com 96 094_OE0514_Subsea2_Aker_New.indd 96 4/19/14 8:39 AM