Petroleum Development Oman (PDO) says it still sees in excess of a quarter of crude oil production coming from Enhanced Oil Recovery (EOR) despite the relatively high capital cost of such ventures. “Despite the complexity and cost of EOR projects and the need to prioritise low unit technical cost oil, EOR remains a central pillar of PDO’s evolving portfolio. It is anticipated that by 2025 more than 25 per cent of PDO’s production will come from such projects,” the nation’s largest oil and gas producer said in its newly published PDO Sustainability Report 2016.
A number of commercial-scale EOR projects are currently in operation based primarily on miscible gas injection (MGI), chemical and thermal technologies. At the same time, the company is also pursuing the testing and development of a string of “novel EOR technologies” which it hopes to deploy, once established as commercially viable, in collaboration with international partners. A case in point is the Habhab ultra-heavy oilfield, the hydrocarbon potential of which PDO plans to develop with technical assistance from an international partner.
The biggest of its portfolio of EOR schemes currently in operation is the Marmul polymer project, which as exemplified PDO’s successful application of enhanced oil recovery methods for boosting production. Over the six years since it has been in operation, the Marmul project has delivered around 12 million barrels of oil. It also paved the way for the successful rollout of the second phase in 2015, entailing the injection of polymer into a further 19 injectors.
“The additional injectors have been injecting polymer smoothly and an increase in oil production due to this was observed in 2016 with an oil gain of about 1,800 barrels per day (bpd),” said PDO. Last year, seeking to build on its success, PDO undertook the trial of an alkaline-surfactant-polymer (ASP) flooding pilot at Marmul. The results were gratifying: output rose 30 per cent — well above the target of 20 per cent, while the quality of the produced oil was emulsion-free as well.
“This encouraging outcome from the trial uplifts the commercial outlook for (Alkaline-Surfactant-Polmer) full-field implementation, and a feasibility study is planned to start this year,” the company said. Elsewhere in Block 6, near miscible gas injection (MGI) targeting the Birba field has yielded an additional 8 million bpd of oil for 5.5 billion m3 of gas injected over the past 23 years. MGI is also on target to achieve up to 45 per cent recovery from infill horizontal drilling and additional gas injection.
MGI has also proved a game-changer at Harweeb 2AB where gas injection has helped deliver an increment 10 million barrels of oil to date. Other MGI-related successes of the past year include the commissioning of the Sakhiya A2C mini flood and the Al Noor 3A sour miscible gas injection pilot with positive initial indications, according to PDO.
At Qarn Alam in central Oman, thermal gas oil gravity drainage (GOGD) has helped deliver 6 million barrels of oil based on the injection of 2.9 million tonnes of steam over the past six years. Output rose an incremental 650 bpd above target last year.
Output from the Amal field, the subject of a steam flood, was 12,824 bpd as the year’s average oil production, the company added.