Petroleum Development Oman (PDO) has launched a design and procurement tender for a major enhanced oil recovery (EOR) project at two oilfields in the sultanate.

The company released bid documents for the project on 20 January and has asked prequalified contractors to submit bids by 9 February.

The state oil and gas developer expects to award a contract by 31 July.

The deal covers detailed engineering design work and equipment procurement for EOR schemes on two of its oil and gas fields.

It is part a PDO programme of EOR projects to maintain oil and gas production at its ageing fields by injecting gas into reservoirs to maintain pressure and therefore output.

The first part of the scheme involves a 400,000-square-metre-a-day gas compressor at the Al-Noor field, with gas dehydration facilities, two gas injection units, pipelines, electrical design work, and associated computer control equipment and software.

The second project is for a 5.5km pipeline linking an existing gas compression unit with gas injection facilities at the Sakhiya field. This development is regarded as the most technically complex because the pipeline and injection facilities must be able to handle pressures of up to 660 bar, seven times more than is normally used in EOR projects.

The Sakhiya field is particularly specialised because of the gas being used for injection. The gas is concentrated hydrogen sulphide, a highly toxic chemical.