In conventional oil and gas, water management is an integral part of a profitable operation
By Jeff Gunderson
Water is an essential component in oil and gas production, and effectively managing its use from source to disposal can be critical not only in terms of controlling costs but also for addressing other operational issues and considerations. Indeed, the way in which water and wastewater are strategically managed at conventional oil field and refinery sites can directly influence the bottom line, but it can also bring the added benefits of mitigating risk, improving performance, simplifying processes, and protecting future productivity.
Water management strategies play a key role in successful upstream oil and gas operations, said Greg Mandigo, application engineering manager of industrial concentration at Aquatech. As an example, in the water-scarce region of Western Canada, Mandigo said operators are focusing on turning waste stream liabilities into positive assets for plants.
“With the availability of freshwater limited, producers routinely employ produced water treatment technology to condition the produced water for recycling as boiler feedwater for steam generation,” Mandigo said. “But in many cases, the lost opportunity is the blowdown stream leaving a once-through steam generator (OTSG). One of the significant drawbacks of OTSG technology is that only about 80 percent of the boiler feedwater is converted into steam, leaving the remainder as boiler blowdown, which represents a relatively large water flow rate and a liability. However, by converting that waste into a high-quality water, it can be reused in steam generation.”
Mandigo advised that the best technology suited for the recovery and recycle of OTSG blowdown streams is vertical-tube falling film evaporation technology. “The water quality of the evaporator distillate is far superior to the quality achieved by a conventional water treatment system and this serves to improve the boiler feedwater quality, protect the integrity of the OTSG, and reduce OTSG mechanical cleaning frequency.”
According to Mandigo, there are many cases, globally speaking, where the OTSG blowdown stream would go to disposal, either by injecting on-site into a deep well or by collecting and transporting the wastewater to a remote water disposal location. “In water-scarce regions like the oil sands of Western Canada, such a plan would result in very high operating costs, specifically because of a general lack of deep wells in the region that can be used for disposal. Moreover, the producer would be exposed to substantial risk since the operation would become dependent on a third party for wastewater disposal, which could impact the ability to produce oil and maintain positive revenue.”
In such facilities, Mandigo said an evaporation system can be used to both optimize water recovery and minimize the amount of brine for disposal, typically by as much as 95 to 98 percent. “One of the common misperceptions in the industry is that an evaporation system for water balance optimization is only used when it is required to meet regulations, but what we’ve seen is that there are also strong economic incentives for producers to maximize recycle rates — not only for cost savings associated with brine disposal but also for improving OTSG performance and reliability, and enhancing cost savings in the boiler feedwater treatment system,” he said.
Recent project examples leveraging advanced treatment technologies demonstrate how strategic water and wastewater solutions can address a primary issue while also generating efficiencies and supplemental benefits across project sites.
Mobile Water Treatment Solution Mitigates Risk, Provides Long-Term Water Security
In Bahrain, one of the most water-stressed countries in the world, the Bahrain Petroleum Company (Bapco) is employing advanced mobile water treatment units at its Awali refinery located along the country’s eastern coast for converting seawater into usable, highly pure source water. The mobile water technology, supplied by GE Water & Process Technologies, provides Bapco with a cost-effective solution for on-site desalination, ensuring a continual boiler feedwater supply and eliminating the need to deliver water to the refinery via tanker truck.
Previously, the refinery’s existing desalination units produced limited in-house distillate water, which required Bapco to truck in additional water to make up the shortage — a method that caused gridlock on refinery roads and introduced an element of risk from having an unusual number of tankers inside the refinery operating area.
“The high truck volume on the site was a disruption to normal operations, so alleviating that requirement removes a huge logistical burden and mitigates the previous environmental health and safety concern associated with the truck traffic,” said Kevin Cassidy, global leader of engineered systems at GE Water & Process Technologies.
The additional benefit of incorporating an onsite water treatment plant is that Bapco effectively assures its water security, which is especially significant in such a water-scarce region. “The solution provides a reliable, long-term water source, reducing future water supply uncertainty,” Cassidy said. “Additionally, by outsourcing its water treatment, Bapco can focus on its core competency.”
The turnkey solution at the Awali refinery includes six mobile seawater multimedia filter containers, five mobile seawater reverse osmosis containers, two mobile brackish water reverse osmosis containers, and four diesel-operated electrical generators. “The modular approach provides flexibility,” Cassidy said. “If there is ever an increase or decrease in demand or a change in water quality, we can flex by adding or decreasing onsite units or bringing in additional pretreatment.”
Modular crystallization technology delivers multifaceted benefits at SAGD facility
A steam assisted gravity drainage (SAGD) facility in Alberta, Canada, will employ an advanced crystallizer system from Veolia Water Technologies as a solution for minimizing excessive costs for disposal of evaporator blowdown waste. Veolia’s Modular Bulldozer Design (MBD™) using HPD® crystallization technology is anticipated to reduce blowdown waste volume by up to 80 percent, substantially decreasing expenses related to waste hauling and disposal. In addition to providing a significant cost mitigation, the solution will also generate several ancillary benefits.
As the primary driver for implementing Veolia’s treatment technology, the facility owner was motivated to address the expense liability associated with managing its evaporator blowdown — a highly contaminated waste stream requiring a specialized disposal solution, according to Mark Nicholson, senior business development manager with Veolia Water. “Because of its high pH and elevated concentration of dissolved silica, this waste can’t be injected down a conventional deep well due to plugging risks,” Nicholson explained. “Instead it must be trucked a long distance to a salt cavern for disposal, which results in high transportation costs. And, since very few salt cavern facilities are available, the disposal costs run at a premium.”
By significantly lowering the amount of waste that needs to be hauled, the Veolia solution will bring the added benefit of effectively removing an average of six trucks per day from the road. “The Alberta region of Canada is a highly remote and pristine area, and getting those trucks off the road is a really big deal,” Nicholson said. “Those trucks must travel up to 400 kilometers just to get rid of 5,000 gallons of waste. Reducing that truck volume helps mitigate the risks associated with an accidental spill.”
As another benefit, the MBD crystallizer will recycle up to 80,000 m3 of water annually for reuse in generating steam, which in turn will be utilized for producing additional oil — an auxiliary benefit that not only works to fully utilize resources but also helps to justify project costs, Nicholson added.
“The additional water that is recovered from the MBD crystallizer will help alleviate the need to pull water from fresh or lightly saline aquifers for use as makeup water,” said Steve Michaluk, senior sales manager at Veolia Water North America. “Currently, the water that is extracted from these sources represents between 5 and 10 percent of the total amount of water that is used for steam injection.”
Recycling more water will help conserve freshwater resources and is seen as a positive action from a regulatory standpoint, according to Michaluk. “The facility owner will be credited for increasing its ratio of recycling according to Alberta Directive 081, which sets limits for water disposal and reporting with respect to ongoing SAGD operations for existing plants and permitting of new capacity for SAGD facilities.”
About the Author: Jeff Gunderson is a correspondent for Industrial WaterWorld. He is a professional writer with over 10 years of experience, specializing in areas connected to water, environment and building, including wastewater, stormwater, infrastructure, natural resources, and sustainable design. He holds a master’s degree in environmental science and engineering from the Colorado School of Mines and a bachelor’s degree in general science from the University of Oregon.
