Aker Solutions said it is working with a group of leading oil and gas operators in a joint industry project that aims to make subsea gas separation a reality.
Using CO2 injection to increase recovery rates in offshore oil and gas fields can improve the economics of a field significantly, but so far, the separation of ‘back-produced’ CO2 from the well-stream has been considered carried out on an existing platform, adding cost and making the concept economically unattractive, Aker Solutions said.
Now the Norwegian-based firm is working with energy companies Total, Pertamina, Equinor and industry group the CO2 Capture Project (CCP), including members BP, Chevron and Petrobras, in a joint industry project (JIP) to identify required membrane qualities for a subsea gas and CO2 separation process, to minimize pretreatment needs and avoid large processing modules.
Flooding an oil field with CO2 increases recovery rates, and extends the life of an offshore field. Aker Solutions has developed new concepts for subsea processing of well streams from CO2-flooded oil fields, in which CO2-rich gas is separated, compressed and reinjected back into the reservoir. The hydrocarbon-enriched gas can then be routed to the topside production facility.
Subsea gas separation has the potential to make CO2-rich gas fields commercially viable.
A prerequisite for the concept to be technically and economically attractive is that the gas separation is done with robust membranes that reduce pretreatment requirements and remove the need for large processing plants.
Also, the qualified operating range for relevant membrane materials do not match the optimal operating conditions for gas separation on the seabed. Hence, testing must be done in order to obtain knowledge about membrane performance under these conditions.
The project will perform tests of different membrane qualities under relevant conditions related to pressure, temperature, gas composition and rates. The tests will be carried out by the SINTEF research institute in Norway. The project also includes technical and economic engineering studies to assess the technology concept based on the test results.
The project aims to qualify membrane qualities that are suitable for bulk separation of CO2 in a typical subsea process, and confirm technical and economic use of subsea processing as a favorable concept for the realization of offshore CO2 EOR in combination with reinjection and storage of CO2.
Aker Solutions delivered the first subsea gas compression system to Equinor for the Åsgard field offshore Norway. The system has been in operation with no unplanned downtime since it was installed in 2015. The subsea gas separation technology in combination with the subsea gas compression technology could make offshore handling of CO2 for EOR technically and economically attractive.
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