Key Advantages
The key benefits DGC is able to bring to both green and brownfield sites include a substantial acceleration in production rates and maximised Ultimate Recovery (UR) by lowering reservoir abandonment pressure. The technology achieves this through improved vertical lift performance and increased well draw down, resulting in reservoir stimulation and maximum gas recovery.
Through a combination of Corac Group plc’s proprietary gas bearing system and its direct drive, gas filled, high speed permanent magnet motor, these key enabling technologies allow an axial turbo-compressor delivering up to 500 kW, to achieve the necessary rotational speeds for efficient operation downhole in a gas well.
Corac Group plc’s innovative design has eliminated all couplings, gearboxes, shaft seals and liquid lubrication systems – in short, all the vulnerable, wearing components – to produce a drive system with essentially one moving part and no contacting surfaces in operation.
The key technological breakthroughs are:
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Gas filled brushless permanent magnet motors
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DC electrical transmission to downhole power electronics
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Driver and Compressor on one piece shaft
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Gas bearing technology
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Low speed blading
Reliability has been engineered from the outset.
An important outcome of a feasibility study carried out in 2002 was the realisation that the introduction of downhole gas compression earlier in the production cycle of maturing gas fields can produce very significant improvements in financial returns through accelerated revenue streams and increased UR.
It will extend the production plateau of producing gas fields by bringing forward tail-end production, thus delaying the need for investment in new facilities or the development of new fields. From the reference fields studied, incremental production gains of between 28% and 42% were found to be possible with only very modest pressure ratios.
In addition, by accelerating production rates and increasing ultimate recovery by lowering the reservoir abandonment pressure, downhole gas compression is seen to offer a potential solution for the development of otherwise sub-economic gas assets.