As the cost and supply of fuel continues along its bumpy road, more emphasis has been placed on tapping into the remainder of the world's oil reserves. Canada is home to one of the world's two largest sources of bitumen-a thick, sticky crude oil that joins sand, water and clay to create what are known as oil sands.
In 1967, the Great Canadian Oil Sands Company (GCOS) opened for business with the intent of producing 31,500 barrels of oil per day from the oil sands in northern Alberta. Today, the combined efforts of the 87 active oil sands projects in Alberta alone are estimated to produce more than one million barrels per day, with an anticipated production rate of four million barrels per day by the year 2020.
Bitumen can be extracted by surface mining or subsurface extraction. Mined bitumen must undergo a refining process that is fully dependent upon the reuse of inordinate amounts of water. As a result, the extraction, dilution and transportation involved in the bitumen recovery process require the use of powerful, durable pumps.
Recycling
In the 40-plus years since the GCOS opened for business, the process of extracting bitumen has evolved with an awareness of sustainability that includes sensitivity to the amount of water used. In fact, a report from Canada's environmental think tank, the Pembina Institute, stated that, "To produce one cubic meter (m³) [264 gallons] of synthetic crude oil (SCO) (upgraded bitumen) in a mining operation requires about 2 - 4.5 m³ [roughly 530 - 1,200 gallons] of water (net figures)."[1]
In an effort to reduce the strain this places on the Athabasca River, producers have concentrated on increasing water reuse throughout the process. Part of this reformation has been the introduction of portable, diesel automatic self-priming extreme high head centrifugal pumps.
Recalls Godwin Pumps Senior Service Technician Paul Natalino, "Years ago, the reclamation ponds in the oil sands had a floating ramp in the middle of them with submersible pumps hanging from it. Technicians would have to walk on a narrow catwalk in conditions up to 40 below in the ice and wind to service those pumps. We introduced self-priming centrifugal pumps for two critical reasons. One, there was no safety issue involving technicians working on an icy catwalk, and two, there was no need to run high voltage lines over water.
"The only other alternative had been wet-priming pumps, which were not easy to work with in extremely cold and windy conditions. The introduction of the self-priming pump that could remain on shore and could handle the mixture of sand and water was tremendously successful. The pumps are now enclosed in heated tents. Maintenance can be performed in a safer way."
Self-priming centrifugal pumps have since played a significant role in the extraction and delivery of bitumen and in the reclamation process. These types of pumps are used to supplement the process in applications including:
Increasing Process Water
Canadian-owned fluid management company Canadian Dewatering LP (Canadian Dewatering) sees a significant amount of activity in the oil sands. In its most recent undertaking, Canadian Dewatering supplied a temporary, variable speed, diesel-driven booster pump package to increase process water feed demands from 8,000-gpm to 24,000-gpm at 196-psi.
Canadian Dewatering developed a rental solution that included 18 diesel-driven 8-in by 6-in (200-mm x 150-mm) pumps controlled by a centralized programmable logic control (PLC) and interfacing with a client-supplied master signal speed control to meet the demands of increased production.
Open Pit Dewatering
Portable pumps are used to dewater the open pit from which the bitumen is being extracted.
Raw Intake Water
Portable pumps are often used to supply raw intake water from the Athabasca River to be heated and mixed into a slurry for transport via the hydrotransport pipelines to the primary extraction plant.
Emergency Decant If Transport Line Clogs or Breaks
If a permanent pump breaks and there is not enough pressure to transport the product through the hydrotransport pipelines, portable pumps can supplement the system while the repairs are made.
Cooling Water for the Coke Basin
After being separated from the clay and water and treated with naphtha, the bitumen goes through upgrading to remove the naphtha and then heating in furnaces to remove petroleum coke. Portable pumps can be used in this process to provide cooling water for the coke basin, in addition to tank cleaning, if and when necessary.
Emergency Diversion of Wastewater
Tailing ponds have received increasing attention in the Canadian press, as strict environmental regulations now call for tailing ponds to be ready for reclamation no more than five years after they are no longer actively used. As with any other body of water, these tailing ponds must be contained. Producers rely on portable pumps to contain the recycled wastewater that makes up tailing ponds.
Surviving the Elements
By nature, pumps do not work in the world's most glamorous places. The Athabasca oil sands are no exception. The most highly requested features of those pumps selected for oil sands duty include:
Weather Resilience
The Athabasca County website lists the average temperature in Athabasca in July as 16-deg C (61-deg F), with the average lows between -15-deg C (5-deg F) and -10-deg C (14-deg F). Most pump data sheets list the maximum operating temperature of the fluid being pumped, without regard to the obvious: If the liquid is frozen, it cannot be pumped. Pump ends can be operational in extremely cold conditions, provided that proactive measures are taken.
First and foremost, when possible, pumps in extreme temperatures such as those found on Athabasca should be contained in heated enclosures. In addition, consider equipping pumps operating in extremely cold conditions with heat tracing, drains and insulation.
When preparing a backup pump for cold weather, drain the discharge line and volute so that the suction line and volute drain enough to prevent damage to the volute, wearplates and seals if any remaining water freezes and expands. Consider removing the ejector ball in colder months to prevent freeze-ups by allowing the volute to drain automatically during unexpected engine shutdowns (note that this option may extend priming time).
In addition, consider installing a volute drain hose that extends from the volute to below the waterline on the suction side so that the water column in the line can help re-prime the pump.
Specification Flexibility
Pumps have ratings for pressure, head and flow. To meet the flexibility required in the oil sands, one pump would need to be able to achieve TDH between 100- and 130-ft (30- and 40-m), flow between 0- and 5,000-gpm (1,136-m3/h) and pressure between 60- and 190-psi (4- and 13-bar). In addition, the ability to handle viscous liquid is essential.
Portability
Since one pump can be used in various applications throughout the bitumen refining process, it pays to have a pump that is portable. Although oil sand refineries generally manufacture their own diesel fuel and electric power, diesel pumps are more heavily used than their electric counterparts because they can be more easily transported from site to site throughout the vast production areas.
Communication
Remote telemetry is on the wish list for portable pumps operating in oil sands. The ability to track maintenance intervals, control flow, communicate pump status and operate independently and automatically play an important role in continuing production at each operational point where portable pumps are used.
Summary
As the dependence on Canada's vast oil sands deposits increases, so does the emphasis placed on the environmental impact. Regardless of the extraction process, the availability and maneuverability of water is critical to the production process. More companies are turning to portable, automatic, self-priming centrifugal pumps that can meet the pressure, flow and lift demands necessary to keep water moving without placing an additional strain on natural resources.
References:
Troubled Waters, Troubling Trends, May 2006, The Pembina Institute.
Pumps & Systems, April 2009