International engineering, procurement and construction (EPC) firms have submitted commercial proposals for an estimated $300m brownfield contract at the Zubair oil field in the south of Iraq.

The firms submitted their prices on 30 March to the field’s developer, Italian oil firm Eni, after seeing the deadline extended by just a week from 23 March, according to a source close to the deal.

At least five firms submitted technical proposals in September 2011, including three Italian firms; Bonatti, Techint and Tecnimont; Punj Lloyd of India and Dubai-based Dodsal.

Technical clarification meetings were held in Italy with bidding firms on 13-14 February for the scheme, which covers the refurbishment of the Zubair field’s existing facilities, which include two gas compressors.

Bids were submitted in February for greenfield production facilities worth an estimated $1bn, but Eni is yet to choose a contractor. Four bidders submitted offers, Italy’s Saipem, Samsung Engineering and Hyundai Engineering & Construction, both of South Korea, and the UK’s Petrofac with Japan’s JGC Corporation.

Contractors are also still waiting for news from Eni for a final deal to build initial production facilities (IPFs) consisting of six oil trains which were initially tendered in April last year. Eni shortlisted only three firms; Weatherford and Schlumberger of the US and a joint venture of Monaco-based Unaoil and Italy’s Rosseti Marino.

The engineering for the deals has been prepared by Saipem.

Eni leads a consortium with the US’ Occidental and Kogas of South Korea for the development of the 4-billion-barrel field. The partners plan to invest $20bn to lift production to a plateau of 1.12 million barrels a day (b/d) by 2017 for a fee of $2 for each barrel.