Heavy crude oil and its role in energy transition

Heavy crude oil is a dense hydrocarbon with a low API gravity (generally below 20∘) and high viscosity, which distinguishes it from light crude oil. Its complex molecular composition, often rich in asphaltenes and with high sulfur content, poses serious operational challenges. These challenges are particularly evident in its extraction, transportation and processing from large global reserves such as the Orinoco Belt in Venezuela.

To transform this viscous, polluting material into clean, transportable fuels, costly, energy-intensive deep conversion processes are required. Despite concerns about CO2 emissions and regulatory challenges (such as IMO 2020), the vast abundance of heavy crude oil guarantees it a critical role in the global energy security matrix during the transition to more sustainable sources.

The great energy challenge

The high operational complexity and environmental impact of heavy crude oil generate an excessive Energy Intensity for refining. This problem is exacerbated by strict global regulation (IMO 2020), which compromises the economic viability of reserves such as the Orinoco Belt.

What is heavy crude oil? Definition and classification

This technical analysis is part of Inspenet’s Energy Pillar, focusing on Process Engineering in the Oil & Gas sector in the Downstream value chain (Refining and Marketing).

Heavy crude oil is defined mainly by its physical properties, which distinguish it from intermediate and light crude oil. The most widely accepted classification is based on API (American Petroleum Institute) Density and viscosity. A crude oil is considered heavy when its API gravity is less than 20∘. In contrast, extra-heavy crude (or extra-heavy crude) has an API Density less than 10∘, a density comparable to that of water.

The low API gravity implies that the oil type is dense and, crucially, has a high viscosity. This resistance to flow is measured in centiPoises (cP) and represents the first major operational challenge, requiring heating, dilution or the use of downhole pumps only for initial extraction and transport.

API density, viscosity and sulfur: Key properties

In addition to API gravity and viscosity, the chemical profile of heavy crude oil is marked by three critical components that determine its market value and refining challenges:

1. High sulfur content: Most heavy crudes are classified as sour crude. This contaminant is the main cause of corrosion in refining assets:
   • It must be disposed of by costly hydrotreatment to comply with environmental regulations.
   • At high temperatures in distillation and cracking units, sulfur reacts to form corrosive compounds, leading to sulfidic corrosion in steel alloys. In addition, hydrogen sulfide can cause hydrogen induced cracking (HIC) and sulfide stress cracking (SSC) in reactors and pressure vessels, severely compromising Mechanical Integrity and forcing unscheduled shutdowns.
2. High metal and nitrogen content: Heavy crude oil contains higher concentrations of metals (vanadium and nickel) and nitrogen.
   • These compounds act as chemical poisons to catalysts within hydroprocessing reactors (such as hydrocracking), causing their irreversible poisoning and premature deactivation. This impacts asset availability by forcing costly and early shutdowns for catalyst replacement.
   • Refineries should use guard bed catalyst to protect the valuable main catalyst beds from this damage.
3. Rich in asphaltenes: Asphaltenes are complex, heavy and stable macromolecules.
   • The management of asphaltenes is the main cause of the difficulty and high cost of deep conversion, as they define the “bottom barrel”.
   • Their high presence is the main cause of clogging and fouling in heat exchangers and piping, especially when temperature or pressure conditions change. This drastically reduces heat transfer efficiency and operational availability of the units by requiring frequent cleaning.

Crude oil types and technical classification

To complement the detailed information on API Gravity and sour crude oil classifications, below is a video courtesy of Kimray Inc. that illustrates the key differences in the global market:

Operational challenges: Transportation and refining

The challenges of heavy oil do not end at the well. High viscosity makes it difficult to move, requiring dilution or heating systems for pipeline transport. However, the biggest technical and economic hurdle is in the refineries.

Heavy crude is the most complex cargo, due to its high percentage of residue and contaminants. This requires refineries to invest in expensive deep conversion units to efficiently transform the bottom barrel and ensure a positive refining margin, which in turn translates into higher energy intensity per barrel.

Conversion processes: From bottom barrel to utility products

The key to refining heavy crude oil is the upgrading process. The bottom barrel is the fraction that remains after vacuum distillation and contains most of the asphaltenes and metals. To convert this heavy and worthless feedstock into light fuels (gasoline, diesel), a dual strategy is used:

• Contaminant removal: By hydrotreating (hydrotreatment) to remove sulfur and nitrogen, and by protecting the catalysts with guard bed catalyst.
• Molecular breakage: By using thermal or catalytic processes that break down the long hydrocarbon chains.

Coking, Hydrocracking and FCC: Deep conversion

Refineries that process heavy crude oil operate specialized deep conversion units. Three of the most relevant technologies for upgrading are:

• Coking: A thermal process that uses extreme heat to “crack” heavy molecules, leaving petroleum coke (a carbon solid) as a by-product. It is highly effective in eliminating bottom barrel.
• Hydrocracking: High-impact catalytic process that uses hydrogen at high pressure to break down and saturate molecules, producing high-value, low-sulfur fuels. It is the most modern option, but also the most expensive.
• FCC (Fluid Catalytic Cracking): Although historically used for gas oils, modern units have been adapted to process heavier fractions.

Geopolitical context and world reserves

Heavy and extra-heavy crude oil reserves are immense, exceeding light and medium crude oil reserves, underscoring their long-term importance in energy security. These resources are not evenly distributed, but are concentrated in geographic giants.

Knowledge of these locations is key to understanding the geopolitics of global supply, the development of transportation infrastructure and the operating costs associated with managing this type of crude oil.

Orinoco Belt and Alberta: Largest global reserves

The two dominant heavy and extra-heavy oil regions are the Orinoco Belt in Venezuela and the Alberta Oil Sands in Canada.

1. Orinoco Belt (Venezuela): Contains the largest proven reserves of extra-heavy crude in the world, a resource that requires intensive heavy oil upgrading or dilution with light sweet crude in order to be exported to high conversion refineries, particularly in the U.S. Gulf Coast.
2. Alberta Oil Sands (Canada): Although technically a bitumen that requires mining or assisted oil recovery (SAGD), the resulting product is processed as synthetic heavy crude oil (synbit), ensuring a stable, high-volume supply to the North American market.

The impact of environmental regulations

The future of heavy crude oil is inextricably linked to environmental regulations and the global drive to reduce CO2 emissions.

The main challenge is twofold: the high energy intensity required for upgrading and the high sulfur content of the product. Modern regulations are designed to penalize fuels that do not meet strict cleanliness limits, directly affecting the economic viability of this resource.

IMO 2020: Sulfur and sweet crude oil demand

A crucial example is the International Maritime Organization’s IMO 2020 standard. This regulation imposed a 0.5% limit on sulfur content in global marine fuel oil. This change generated an immediate demand for sweet crude and VLSFO (Very Low Sulfur Fuel Oil), forcing refineries to maximize the production of clean distillates.

For those processing heavy and sour crude, this accelerated the need to invest in deep conversion units or face reduced refining margins.

Technological solutions for sustainable heavy oil

The long-term viability of heavy crude oil depends on investment and the adoption of technologies that neutralize its high energy intensity and carbon footprint. The industry is focused on two pillars to maintain its role in the energy transition: reducing emissions and optimizing refinery processes.

• Carbon Capture and Sequestration (CCS) as emissions mitigation

Carbon Capture and Storage (CCS) is a crucial enabler to reduce the environmental impact of heavy oil without stopping its use. This system has the function of trapping the CO2 emitted during intensive upgrading processes and storing it in subway geological formations, preventing its release into the atmosphere.

The implementation of CCS in refineries is seen as a strategic investment to meet climate targets and improve the long-term economic viability of heavy crude oil.

• Green hydrogen and advanced catalysts in refining

The desulfurization process is vital to comply with regulations such as IMO 2020, but it traditionally consumes gray hydrogen, which generates CO2. The modern trend is the incorporation of green hydrogen, produced by electrolysis with renewable energies, which allows clean desulfurization with less environmental impact. In parallel, the development of advanced catalysts, more resistant to impurities such as asphaltenes and metals (Ni, V), facilitates deep conversion reactions at lower temperature and pressure, increasing energy efficiency by up to 15%, according to the IEA.

Key strategic solutions

To overcome the technical challenges, the industry is betting on strategic investment focused on two pillars:

• Deep conversion technology: Implementation of Coking and Hydrocracking to efficiently transform bottom barrel.
• Sustainable mitigation: Adoption of Carbon Capture and Sequestration (CCS) and green hydrogen to reduce CO2 footprint and ensure compliance with IMO 2020.

Conclusions

Heavy crude oil remains a strategic and irreplaceable resource in the global energy matrix, with its vast reserves (especially in the Orinoco Belt and Alberta) guaranteeing its permanence in the coming decades. However, its role in the energy transition is conditioned by the sector’s capacity to face its inherent challenges.

The key to its future viability lies in technological innovation. Investments in deep conversion units (such as Coking and Hydrocracking) and the adoption of mitigation measures such as Carbon Capture and Storage (CCS) are essential to reduce its energy intensity and CO2 footprint. Furthermore, the adaptation to global regulations such as IMO 2020 demonstrates that responsible environmental management and operational efficiency are now determining factors for the refining margin.

In short, heavy oil will not be phased out in the short term. Its successful continuation will depend on a strategic balance between ensuring energy security and an inescapable commitment to sustainability through cutting-edge technology.

Successfully managing these technological and regulatory challenges requires the best professionals and companies specialized in deep conversion and ESG solutions. Find industry leaders in our Corporate Directory.

The energy transition is an ongoing process. If this article has been helpful to you in understanding heavy crude, we invite you to continue exploring the challenges and solutions in sustainability and technological innovation.!

References

1. Pulso energético: “El Papel del Petróleo y el Gas en la Transición Energética”
2. Petro Punto: “Tecnologías emergentes en el refinado de Petróleo”
3. Agencia Internacional de Energía: “Innovaciones tecnológicas y métodos de mitigación”
4. Real Instituto Elcano: “Consideraciones ambientales y de seguridad energética”

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