S. Fontaine, Veolia Water Technologies & Solutions, Orlando, Florida; and R. GUTIERREZ, Veolia Water Technologies & Solutions, Tomball, Texas
The global crude oil supply today looks very different from what it was historically, driven by shifting supply constraints, technological advancements, economic opportunities and other contributing factors. Amid geopolitical changes and global crude trade volatility, crude refining feedstock supplies are expected to evolve rapidly. With these conditions in play, discounted opportunity crudes present a compelling risk/reward scenario. While these crudes offer potential for higher profit margins, their variable feed quality introduces unforeseen processing risks that can bring operational unrest.
Specifically, the instability and incompatibility of opportunity crudes can lead to downstream problems such as fouling, scaling, corrosion, crude oil tank sludging, oily desalter brine, excess slop generation and desalter upsets. Fouling in critical equipment like preheat exchangers and furnaces reduces heat transfer efficiency, resulting in heat loss, decreased plant throughput, higher maintenance costs and unplanned downtime. These issues impact production and profitability. Opportunistic crude buyers must therefore balance the pricing advantages of these crude supplies against the operational challenges they pose.
Limitations of traditional crude stability testing. Traditional methods to evaluate crude feedstocks often rely on time-intensive laboratory testing, leaving refiners reactive rather than proactive when addressing processing challenges. In some cases, refineries skip testing altogether, adopting a “best guess” approach that can amplify operational risks.
Industry-standard ASTM crude stability methods—such as D7060, D7061, D7112 and D7157—are based on solubility parameters like P-value and S-value, measured through optical detection. These methods are tedious and require extensive sample preparation, including the use of chemicals such as heptane to precipitate asphaltenes and toluene to re-dissolve them, altering the original sample in the process.
The newest standard test, ASTM D8253, employs a manual microscopy-based approach that also relies on optical measurements and uses heptane to precipitate asphaltenes and titration with toluene until an endpoint is reached. Similar to the other methods, D8253 is complex and time-consuming, requiring three iterations and mathematical calculations to derive a stability value.
When it comes to optimizing refining processes, time is paramount, and the limitations of traditional crude stability methods highlight the need for faster, more reliable solutions to predict crude oil compatibility and processing risks.
A predictive solution for securing stable crude supplies. To manage operational unrest, the authors’ company’s patented technologya offers refineries a rapid, proactive strategy to address crude processing challenges before they arise. By accurately predicting crude oil compatibility, instability and fouling risks, the technology provides crude buyers, unit operations engineers and other concerned users with advance notice of potential crude processing problems. These issues can subsequently be handled through inventory management, chemical treatment program adjustments and field process optimization.
Unlike time-consuming empirical lab testing, the authors’ company’s technologya employs two rapid specialty tests1 on key markers through easy-to-use benchtop units and a proprietary analytics software tool. Together, they provide more comprehensive guidance than just the standard stability/compatibility measurement.
In the first specialty test, using a drop of crude oil, the process begins with an infrared (IR) scan, which produces a unique fingerprint for each crude sample (FIG. 1). Even crudes with the same name and originating from the same source formation can exhibit vastly different characteristics, and the IR fingerprint captures these nuances. Next, the IR scan is run through the analytics tool to produce: (1) a relative instability index (RIX), which quantifies a crude’s capacity to destabilize itself or other fluids upon blending, and (2) a crude precipitation index (CPI), which provides a measure of the potential precipitant amount upon destabilization of asphaltenes and other colloids in the fluid. The RIX and CPI combination serves as a powerful tool to help refiners optimize blending to decrease downstream issues.
The second specialty test incorporates the measurement of centrifuge solids, which offers a direct method to assess the impact of crude oil instability/incompatibility without changing the nature of the original oil sample. This test bypasses the extensive preparation required by other methods and enables a more accurate prediction of fouling potential, quantifying and classifying the total level of solids (insoluble materials) in a fluid into total centrifuged solids (TCS), toluene insoluble solids (TIS) and toluene soluble solids (TSS). Samples are centrifuged at approximately 70°C (158°F) to eliminate interference from waxes. At that elevated temperature, the method offers better correlation with field conditions. TSS mainly comprises asphaltenes and other relatively organic materials, whereas TIS may comprise relatively inorganic materials such as clays, silica, corrosion products, coke products, coke fines, etc. Historically, crudes with high levels of solids tend to limit desalter performance, produce poor brine quality and cause desalter upset conditions. Combining centrifuge solids with the key predictions from the IR fingerprint generates a fouling potential index (FPX), which characterizes the tendency of a crude oil/blend to foul preheat exchangers and heaters at typical conditions.
The authors’ company’s technologya also supports virtual blend simulations and constrained optimizer using assays or IR fingerprints from historical samples, enabling refiners to predict the instability and fouling potential of different crude blends without the need to use physical samples (FIG. 2). It can also recommend optimal blending strategies within minutes and identify measures to pre-emptively address solids-related challenges in crude feeds.
Actionable insights provided by this technology have allowed refiners to mitigate negative processing impacts while improving crude flexibility and operational reliability, leading to operational calm and profitability.
CASE STUDIES
Case studies of real-world field applications demonstrate how the authors’ company’s technologya can address today’s crude processing challenges and deliver significant paybacks.
Case Study 1: Optimizing feed processing for a U.S. West Coast refinery. A U.S. West Coast refinery faced considerable challenges with processing a transmix oil, which was being routed directly into the refinery’s coker unit. The high-variability blend caused frequent fouling in the preheat and coker systems in addition to excessive slop generation, requiring significant and costly reprocessing. The authors’ company collaborated with the refinery to optimize the RIX of their feed as a function of two critical factors:
The amount of transmix being processed
The injection location for the transmix stream.
Using the authors’ company’s technologya, the team conducted 34 onsite tests over three days to identify the optimal transmix quantity and feed location, drastically reducing the refinery’s pain points while improving operational efficiency.
The RIX value, initially near 7, was successfully reduced to a stable range of approximately 1 by changing the destination of the transmix stream to the crude unit. This change alone increased the coker run length by roughly 25%, resulting in annual savings of approximately $1.4 MM. Additionally, the broader optimization reduced coker furnace and crude preheat fouling, decreased slop generation and minimized reprocessing needs, delivering a total net savings of $10 MM/yr.
By leveraging the authors’ company’s technologya, the refinery achieved substantial cost benefits and improved operational stability in a short timeframe.
Case Study 2: Reducing fouling in dumbbell crude processing. A crude oil refiner processing a "dumbbell crude" blend—characterized by a mix of light and heavy fractions—was experiencing significant fouling challenges in its heat exchangers. The fouling caused substantial heat loss across the unit and required frequent cleaning of heat exchanger bundles between turnaround cycles, leading to operational disruptions and considerable maintenance costs.
Using the authors’ company’s technologya, the team analyzed the crude oil blends and discovered that the RIX was in a critically unstable range. The analytics also identified the FPX with a medium fouling severity (FIG. 3).
Armed with these insights, the team implemented a two-pronged strategy to enhance crude stability and reduce fouling rates:
Anti-foulant treatment: A dispersant-type chemistry was applied to address fouling. This treatment alone decreased the fouling rate by approximately 62%.
Crude stability additive: A stability additive was introduced to manage asphaltene precipitation and mitigate crude incompatibility. This further reduced fouling by an additional 34%.
Combined, these measures lowered the overall fouling rate by 96%. The crude stabilizer effectively kept asphaltenes in the solution longer, addressing the incompatibility highlighted by the RIX. At the same time, the anti-foulant minimized the size of the precipitated material and prevented it from adhering to the heat exchangers by dispersing it into the bulk phase, allowing it to flow downstream without forming deposits.
As a result, the refinery eliminated the need for six bundle cleanings between turnaround cycles, leading to annual savings of approximately $5.7 MM. By lowering the maintenance workload, the solution improved operator safety and decreased the time spent managing issues related to fouling.
From uncertainty to strategic advantage. As future crude oil supplies become even more variable than they are today, refiners require solutions to ensure that increasing crude complexity does not translate into escalating problems. To stay competitive, they must also adopt proven strategies to balance crude cost-effectiveness with operational stability.
With the predictive capabilities of the authors’ company’s technologya, refiners can quickly assess the operational risks of each crude supply and implement mitigation strategies before issues arise. By turning uncertainty into actionable insight, this technologya empowers refiners to process difficult and unknown crudes both safely and effectively, maximizing profitability. HP
NOTE
CrudePLUS
LITERATURE CITED
Teran, C. K., “Crude oil fingerprinting and advanced predictive analytics,” AFPM, 2017.
Sylvain Fontaine is a Senior Application Expert for the hydrocarbon processing industry at Veolia Water Technologies & Solutions. He provides global technical support to the refining industry with a principal focus on crude units, desalting, phase separation, antifoam and solid settling best practices, knowledge management and technology development. Throughout his 42-yr career, Fontaine has held various roles in research, technical and application support, sales and sales management. His responsibilities included servicing, product line management, new product development, marketing and field sales support for cooling and boiler water, wastewater, emulsion breakers, antifoulants and corrosion control chemistries to the refining processing industry. He earned a BS degree in biology from Sherbrooke University in Quebec, Canada.
Rob Gutierrez serves as a Lead Researcher at Veolia Water Technologies & Solutions, based at the Tomball Technology Center in Tomball, Texas (U.S.). Since joining the company, he has developed more than a decade of experience in the refining industry with a focus on phase separation, crude stability, fouling mitigation, finished fuel additives and accompanying advanced analytics. Gutierrez earned a BS degree in chemistry from Sam Houston State University in Huntsville, Texas (U.S.), and his work has resulted in four published patents, with multiple others pending spanning the entirety of the refining industry.
