State-run Saudi Aramco, the world’s largest oil producing firm, is also operating the world’s largest system for water flow into its massive oilfields to maintain their production capacity. But the company says such a system is beset with challenges.
For Saudi Aramco, keeping the nation’s oil fields in optimal condition is not simply an option — it’s a must, Aramco said in its latest bulletin, Dimensions.
Part of this responsibility falls on the shoulders of the company’s Sea Water Injection Department (SWID), which operates the world’s largest seawater injection system. “Water injection for oil fields is critical,” said Mohammed Sowayigh, SWID manager.
“Without water injection, oil production levels cannot be maintained and could be significantly impacted and drop. It’s a necessity,” he added.
Although oil production would not immediately stop without water injection, the health of the oil field would be severely affected, causing a decline in the oil it produces over time. Injected seawater replaces the oil that is extracted from the reservoir.
This offsets the pressure decrease in the field that is caused by oil production, the bulletin said, adding that it is this decrease in field pressure that affects how much oil the reservoir can produce.
The hub and center piece of the seawater injection system is the Qurayyah Sea Water Plant (QSWP), it noted. Inaugurated in 1978, the plant is capable of treating 14 million barrels per day (MMBPD) of seawater.
“That’s equivalent to more than 800 Olympic-size swimming pools, making it the largest plant of its kind in the world,” said Aramco, which has pumped oil for over 70 years.
The complex process of injecting seawater begins when raw seawater from the Arabian Gulf is drawn through an enclosed lagoon and funneled to QSWP.
At this point, the drawn seawater is screened and chlorinated and lifted into two massive open concrete channels, known as Above Grade Canals (AGCs). The AGCs then serve as supply reservoirs for 28 treatment modules.
The modules contain sand filtration media that further separates the water from the solids and a system to remove the oxygen from the water. Six giant cross country pipelines then send this treated water to injection plants in ‘Uthmaniyah, Ain Dar, Shedgum, Khurais, Hawiyah and Haradh.
“The whole operation consists of different parts,” said Sowayigh. “The water from Qurayyah is shipped through a piping network to intermediate stations in ‘Uthmaniyah and Ain Dar. From there, it goes to water injection plants, and then its pressure is boosted and distributed to injection wells along the flanks of Ghawar and Khurais fields.”
The bulletin described such an operation impressive and said that it has taken great strides over the decades.
In the late 1970s, the company’s seawater injection capabilities stood at 5.5 MMBPD at the Grass Root Sea Water Plant, which eventually became QSWP.
Subsequent expansion projects, the most recent being in 2008, made QSWP capable of processing almost three times that amount.
The success of SWID depends on smooth and reliable operations at the plant. Ayedh Al-Otaibi, superintendent at QSWP, believes the plant’s success is attributable to the hard work of its team.
“It’s a strategic plant for the company because it supports the crude production of Ghawar and Khurais. There are more than 200 employees in operations, maintenance, engineering and support. It’s a collective team that works in synergy to keep our production running,” Al-Otaibi said.
The Kingdom’s oil fields are among the largest in the world. Keeping a steady supply of treated seawater flowing into these vast reservoirs through more than 600 wells is not without its challenges, he noted.
“We have to maintain the water quality and achieve the objective of proper reservoir support,” said Mohammed Al Ghamdi, supervisor of Sea Water Engineering.
“There are many specifications we have to meet, which is a challenging task. We have to check the pH of the water, check for suspended solids, bacteria and oxygen. If the water quality specifications are not met, then it would have an impact on the piping integrity and the reservoir,” he added.
Other measurements also are taken to ensure the water quality is within acceptable levels before it is injected into the reservoir. Bactericide is injected into the piping system twice weekly to combat bacteria in the system.
Engineers in SWID also inspect water pipelines and repair corrosion and coating failures. Injection of poor quality water could have devastating effects, causing the tiny pores in the reservoir to be blocked, which would limit the amount of water that can be injected into the well and therefore affect future oil recovery.
And as Sowayigh explained, the Qurayyah plant is also crucial in preserving the Kingdom’s precious water aquifers. “If we didn’t process seawater, we would have to use some of the natural water aquifers like the Wasia aquifer, which has mild salinity, to inject water into the oil fields.
The use of seawater means that we are able to preserve the nation’s natural water resources for potential use by future generations. This is important, especially considering the Kingdom’s arid environment.”