SELEX-Asp: A Clean, Commercially Proven Solution to Partial Upgrading
The topic of partial upgrading in Alberta has received a lot of attention lately. Earlier this year, the Canadian Energy Research Institute and the University of Calgary’s School of Public Policy both published reports discussing the merits of partial upgrading and the status of many technologies in development within this space.
The partial upgrading model is simple: reduce diluent dependency and capture additional value in-province for every barrel of bitumen destined for export.
The majority of Alberta’s bitumen is currently exported as a raw product, and it has become increasingly difficult to justify the economics of building new, full-scale upgraders or refineries in the province. Combined with low commodity prices, regulatory uncertainty for new pipeline approvals, and a projected growth of over 50% in oil sands production by the end of the next decade, implementation of partial upgrading technology in Alberta is the logical solution.
Partial Upgrading Isn’t New
Partial upgrading is not a novel idea – it is a model over 20 years in the making. Proponents of this model have faced many historical barriers to market penetration, including:
Large, integrated oil companies having already invested billions in full-scale upgraders
Competition for capital in a high oil price environment - petroleum industry diverting capital to upstream instead of downstream
Timing is everything, and it is only now that the right social and economic circumstances exist in Alberta that allow the partial upgrading model to gain traction. Currently there is a race to develop new, commercial partial upgrading technologies, with academia and industry experts working towards solutions in the name of innovation, and lots of research funding is at stake.
A Commercially Proven Solution Exists
In the time that it has taken the Canadian petroleum industry to embrace partial upgrading, Well Resources Inc. (Well) was able to successfully commercialize its Selective Extraction of Asphaltenes (SELEX-Asp) technology in other jurisdictions. With 5 commercial units for a nearly combined 40,000 bpd residue processing capacity and almost a decade of operating data, SELEX-Asp has been de-risked for Canadian investors.
What is SELEX-Asp?
SELEX-Asp is a patented, simple, and cost effective technology that is uniquely capable of cleanly removing asphaltenes as solid granules from petroleum residue.
The asphaltene component is largely responsible for the increased viscosity and processing difficulty in heavier oils, and has little economic value. Transport and refining issues associated with asphaltenes are not unique to Canadian crude; asphaltenes exist in crudes all around the world in varying degrees. How best to deal with asphaltenes has been a heavily discussed topic within the industry.
The figure below shows the various components of a single barrel of Alberta oil sands bitumen. When this raw bitumen is exported down a pipeline, it needs to be mixed with 30-40% diluent to meet pipeline density and viscosity specifications.
By subjecting bitumen to the SELEX-Asp process prior to pipeline transport, the low value asphaltene component no longer needs to be transported and diluent dependency is cut to 0-10%. This serves to nearly double the effective bitumen carrying capacity in existing infrastructure. As an added benefit, asphaltene-free bitumen can be sold as a premium feedstock to refineries.
Comparison to Conventional Processes
In typical crude processing, the barrel depicted above is first subjected to conventional atmospheric and vacuum distillation processes to separate the light and heavy gas oil components, leaving vacuum residue.
If the barrel of bitumen is destined for a full-scale upgrader, the vacuum residue is then sent to any number of thermal processing units, such as cokers, which operate at high pressures and temperatures to crack the residue into smaller molecules. As previously mentioned, it is difficult to build an economic case for constructing more of these expensive units in the current price environment.
Conventional solvent deasphalting utilizes a liquid-liquid solvent extraction system to further separate the light residue components from the heavy residue components. As presented in the figure below, due to physical limitations in liquid-liquid extraction, conventional solvent deasphalting exhibits an S-shaped separation curve. Region A shows a certain portion of heavy fractions will still be entrained at the tail end of the light cut. Conversely, Region B shows there will be a certain portion of light fractions entrained in the heavy cut, otherwise known as the “pitch”.
The degree to which light fractions are entrained in Region B of the pitch can severely impact project economics. The pitch will need to undergo further processing to recover additional value.
Heavy fractions entrained in Region A pose their own difficulties because these components can cause fouling issues and catalyst deactivation in downstream processes. To prevent this, solvent deasphalting vendors will often suggest increasing quality through shallow cut extraction. However, doing so sacrifices yield, leaving an even greater portion of lighter ends entrained in the pitch, as shown in Region C below. Costly thermal units are then required downstream to recover the remaining value from the pitch, and this greatly diminishes the economic return.
SELEX-Asp achieves separation through the utilization of solvent at supercritical operating conditions. The system exhibits solid-vapour phase separation (precipitation) and allows for deep and clean separation of vacuum residue with a high degree of specificity. This enables the optimization of both quality and yield.
When residue subjected to SELEX-Asp is cut along Line D in the figure below, asphaltenes are completely rejected as solid granules, which can be disposed in an environmentally responsible manner. The remainder of the residue becomes suitable for conventional refinery processing.
Some of Well’s clients have opted to cut along Line E, producing higher grade refinery feedstock, with the pitch being suitable for a large local asphalt market. Other clients have cut along Line F with the intent of producing feedstock destined for lube oil markets.
Well’s SELEX-Asp technology is ready for commercial licensing. SELEX-Asp is a simple, cost effective technology that exhibits a high degree of flexibility, and it offers Canadians the ability to produce value-added exportable material while simultaneously reducing diluent dependency. Well is committed to the ongoing development and advancement of technologies that are environmentally conscious while simultaneously providing economic benefit.
Interested in learning more? Contact us today at email@example.com.