Oil and water don’t mix. That’s why water is used to help drive oil out of a reservoir and maintain reservoir pressure in a process known as waterflooding.
In that process, seawater and produced water (the water that comes out of the well when oil is produced) are used to physically sweep the oil toward oil-producing wells in a field.
Saudi Aramco’s main seawater treatment facility, Qurayyah, can process millions of barrels per day of water for injection into the giant Ghawar and Khurais oil fields.
To capitalize on the existing water-injection facilities, a new “Smart Water” focus area was launched at the EXPEC Advanced Research Center (EXPEC ARC). At the heart of the initiative is the question: Is it possible to perform minimal chemical alteration to the injection water to help increase recovery while relying on the existing vast water-injection infrastructure and current field-injection practices?
That simple idea is based on optimizing water properties such as salinity and ionic content without adding foreign fluids or chemicals.
“If the current lab results are demonstrated in the field, it will change the way we conduct waterflooding in the company,” said Amin H. Nasser, senior vice president of Exploration and Producing. “The application of this approach will not be limited to mature fields, but also to fields in early development stages.
“This research seems to have changed our perception of waterflooding from being a mere physical process — increasing reservoir energy and sweeping oil toward producers — to one that also entails chemical interactions between reservoir fluids and rocks,” said Mohammed Y. Al-Qahtani, executive director of Petroleum Engineering and Development.
“This is a new concept to this industry and a strategic element of our research excellence,” said Al-Qahtani.
“Smart Water is the most recent research focus area in our broad and balanced research portfolio at EXPEC ARC,” said EXPEC ARC acting manager Samer S. AlAshgar.
“This initiative is unique and distinctive in its simplicity and impact, and the early tests conducted in-house support significant incremental oil-recovery values from Arab-D reservoirs at laboratory scale,” AlAshgar added.
Oil reservoirs are made of porous rocks, and from their microscopic pores, oil is extracted. Injecting conventional seawater displaces significant amounts of the oil from the pores. But some immovable oil remains, clinging to the rock.
Tuning water properties such as salinity and ion composition can change the tendency of remaining oil to cling to reservoir rocks, leading to additional oil recovery. That is one of the potential mechanisms that could explain the substantial increase observed in recent research.