The programme, targeting difficult reservoirs that cannot be produced through primary and secondary means, involves the use of a range of commercial-scale technologies, including chemical EOR, miscible gas injection (MGI) and thermal applications. The goal is to boost the contribution from EOR-based production to more than 23 per cent of PDO’s total output by the year 2025, the majority government-owned oil and gas firm said in its 2017 Sustainability Report.
At the same time, PDO is also investigating a number of “novel EOR technologies” for their efficacy in unlocking difficult hydrocarbon resources. “This is being done through a series of dedicated laboratory and field testing programmes,” the company stated.
Notable among PDO’s chemical EOR initiatives in the Marmul Polymer project, Phase 1 of which came into operation more than seven years ago, delivering around 13.7 million barrels of oil since then. The second phase, centring on the injection of polymer into 19 additional wells starting in 2015, has delivered 840,000 barrels of oil to date. Both phases have contributed an average production of 5,755 barrels per day (bpd) of oil in 2017.
Last year, PDO took a Final Investment Decision to implement Phase 3 of the project, entailing the infill drilling of existing wells in the Marmul Al Khlata reservoir, along with waterflood and polymer rotation. Around 80 million barrels of incremental oil is proposed to be developed during this phase, with first oil anticipated by Q1 2023, according to the Sustainability Report.
Miscible sour gas injection - another type of EOR - has boosted oil recovery from PDO’s Birba field by 22 per cent while yielding an additional 50 million barrels of crude since the project was launched around 23 years ago. The recovery rate is projected to climb to 45 per cent as further infill drilling and additional gas injection activities are undertaken.
At Harweel 2AB, miscible gas injection that began in April 2014 was ramped up to full capacity a year later, with the potential to boost recovery from the field by about 45 per cent. Likewise, gas injection in the Sakhiya field, undertaken as part of the Sak miniflood project, is contributing to positive reservoir pressure and slowing depletion rates.
In Qarn Alam, thermal gas-oil-gravity-drainage (T-GOGD) - a thermal based EOR initiative under way since 2011 - is helping enhance hydrocarbon production from the reservoir. Last year alone, 6.8 million barrels of oil was produced following the injection of 3.3 million tonnes of steam into the Shuaiba oil-bearing formation. Injection rates reached peak levels of 15,000 tonnes per day.
The Amal steam project - a signature EOR initiative of PDO - achieved an average output of 15,716 bpd in 2017. “There was a continued strong steam injection performance with 2017 representing the highest annual average injection rate of around 7,700 tonnes per day,” according to the report.
Source Link: www.omanobserver.om