The oil and gas sector is supporting is carbon capture and storage (CCS), which uses depleted oil fields to store liquid CO2. New facilities being built as part of the project by Qatargas Operating Company (Qatargas) will support QP’s Enhanced Oil Recovery (EOR) initiative.
Dense phase or supercritical CO2, held at sufficient temperature and pressure to keep it in the liquid phase, also has some advantages over water when it is used to purge oil and gas from a well. In a supercritical state, the CO2 can be pumped like a liquid but has the effusiveness of a gas. This means that as it sweeps through the reservoir to push the oil to the riser, it is more effective than water, making for a more efficient process.
In Qatar, there is a major program of investment in the capture and sequestration of CO2, some of which will be used for enhanced oil recovery (EOR).
As part of a project, Sulzer has been involved in the design and supply of suitable pump for pumping dense phase CO2. To this point, similar projects have mainly used either reciprocating or rotary compressors, but more recently a growing number of pumps are being considered. An initial feasibility study was conducted by Qatargas project team and based on further discussion with pump manufacturers, Sulzer’s design of the pump was selected as the best solution in this application.
Sulzer has been involved in this specialist area for almost 40 years. It was awarded the contract to supply an API 610 type BB5, multi-stage, opposed impeller pump with a design pressure in excess of 200 barg, driven by high voltage electric motor and associated variable frequency drive.
Along with the relatively high suction pressures, the lightness and effusiveness of the supercritical CO2 needed to be managed well. A detailed rotor-dynamic assessment and clearance review was conducted along with a thorough investigation into the material selections, both metallic and elastomeric components, along with the casing tightness calculations to ensure leak-free operation under all extreme operating conditions.
Martin Uere, head of global technology for Sulzer Pumps said: “High suction pressures and lightness of CO2 have a significant effect on the design of the pump and this is one of the reasons why other manufacturers have steered clear of this application in the past.”