Petroleum Development Oman (PDO), the nation’s biggest Oil & Gas producer, anticipates more than a third of its oil production coming from fields that use tertiary recovery methods – also known as Enhanced Oil Recovery (EOR) – by 2030.
Accordingly, the majority state-owned energy company is ploughing sizable amounts of money into the development and operation of EOR projects to help sustain oil production, which averaged around 635,000 barrels per day in 2021.
Oil output based on EOR methods is projected to account for around 36 per cent of total production by 2030, up from 13 per cent in 2021. This compares with primary and secondary recovery shares of 39 per cent and 25 per cent respectively in 2030, down from 41 per cent and 46 per cent respectively in 2021.
At present, PDO employs a range of EOR technologies – notably chemical EOR, miscible gas injection (MGI) and thermal applications – to sustain oil production. The company continues to make headway in the implementation and operation of a growing portfolio of EOR projects across its Block 6 concession.
Notable is the Marmul Polymer project where the construction of a third phase will help develop 61 million barrels of incremental oil, with the first oil expected by Q1 2023, PDO revealed in its latest 2021 Sustainability Report. Phase 1 and 2, commissioned in 2010 and 2015 respectively, contributed a total oil production of 26 million barrels as of end-2021.
At the Birba field in south Oman, gas injection over the past 29 years has helped yield an additional 65 million barrels of oil with a current field recovery rate of 24 per cent. “To date, 6.78 billion m3 gas have been injected and we are on target to achieve up to 50 per cent total recovery from infill horizontal drilling and additional gas injection,” said PDO in its report.
Also in south Oman, miscible gas injection is expected to boost total recovery from the Zalzala field to about 50 per cent. So far, 6.67 billion m3 of gas have been injected into the field, with incremental oil to date of about 29.4 million barrels.
PDO’s flagship thermal EOR project centring on the Amal West and Amal East heavy oil fields continues to deliver positive results. Oil production from the Amal Steam project averaged 19,015 bpd in 2021, with steam injection hitting a new high of around 13,920 tonnes per day last year.
“Currently, there are 406 active thermally compliant wells (producers, injectors and observation) in both Amal West and Amal East. These are developed with thermal steam injection from the Miraah solar and heat recovery steam generators in Amal West and Amal East, demonstrating a thermal response in both fields. Reservoir performance continues to improve with steam injection,” said PDO.
PDO’s Rabab Harweel integrated project (RHIP) – the largest and most capital intensive project in the company’s history – joined the company’s portfolio of EOR schemes in June 2019. A complex project in its own right, gas recycling into the Rabab gas field has reached 5.5 million m3/d while mixed gas injection (MGI) into the Sakhiya field was close to its 2021 target of approximately 6.3 million m3/d, the company said.
To help optimise output from challenging reservoirs, PDO is also studying and field-testing a range of novel EOR technologies, such as the injection of foam, surfactant foam, cyclic solvent and simultaneous polymer and water, along with other chemical formulations.
