The Eastern Venezuela Basin (EVB), a geological marvel, is situated along the northern edge of South America, bordered by the Guayana Craton in the south and the Serranía del Interior in the north. Its passive margin and foreland successions, a diverse mix of Cretaceous carbonates and clastics and Tertiary clastics, were meticulously shaped by marine, deltaic, and fluvial environments. The interplay between the Caribbean and South American plates, a pivotal geological process with pre-Cretaceous fault trends, has molded the basin's structural evolution into two distinct sub-basins (Guárico and Maturin) and their associated stratigraphic and structural plays. The main source rocks, the organic-rich Cretaceous shales of the Querecual Formation, stand as a testament to the basin's historical significance, a stratigraphic equivalent to Canje in Guyana and Naparima Hill in Trinidad and Tobago.
In 2020, a selection of 232 fields for 31 billion barrels in the Eastern Venezuela Basin was analyzed based on their discovery year and published data until 2007. In this analysis we have excluded the Orinoco Oil Belt. Proven and probable reserves (P1+P2) were plotted against discovery dates and analyzed with each field's geological main play types. This analysis generated a cumulative exploration curve, which reveals the progression of reserve growth over time (see Figure 1). The size of each point on the graph corresponds to the relative volume of oil reserves associated with each field, with more prominent points representing significant discoveries of light and medium oil, such as Quiriquire (1928), Santa Barbara (1940), Mulata (1941), Jobo (1953), Melones (1955), Melones Central (1955), Morichal (1958), El Furrial (1986), Carito (1987), and Corocoro (1999).
Figure 1 also highlights key geological structural trapping styles, emphasizing antithetic fault plays, which currently dominate the developed oil and gas resources in the EVB. The trendline shows how discoveries evolved, with early exploration phases focused on shallower stratigraphic and structural traps, while later phases targeted more complex and deeper thrust front plays.
The basin has a succession of several key trapping styles, each with distinct characteristics and contributions to the play’s hydrocarbon potential. The antithetic fault trap accounts for 79.6% of the historical production and dominates the traditional areas within the Guárico and Maturin sub-basins. This trap style has historically been the backbone of EVB production. Additionally, 10.9% of hydrocarbon reserves are associated with the inverted flank of the Jurassic Espino graben, associated with the fields in Guárico and the Greater Anaco area. The fold-bend fold traps are in Paleogene and Cretaceous formations, representing 5.42% of reserves along the El Furrial trend (Figure 2).
This visualization explains the crucial role of historical exploration data in comprehending the basin's resource potential. It illustrates how evolving exploration strategies and geological understanding have influenced the growth of reserves in the region (Figure 1).
Drivers Shaping the Exploration Phases
- Phase 1 (1913-1928) - Initial Exploration: Early exploration efforts, guided by oil seeps and surface geology and using rudimentary techniques like refraction seismic and geomorphology, set the stage for the basin's future. Exploration began in the Pedernales-type play in shale diapirs on the northern edge of the Orinoco delta and expanded west to the pitch lakes in the Guanoco (1913) area, where intensive oil and asphalt extraction occurred. The basin's potential for future discoveries, including deepwater plays in the Orinoco delta front, offers a tantalizing glimpse of the untapped opportunities and significant reserves that await discovery.
- Phase 2 (1928-1936) - First Giant Discovery: This period marked improved seismic techniques and interpretation. The first giant fields of medium and heavy oil were discovered in stratigraphic Quiriquire-type Neogene onlaps along the Sierra Oriental before moving southward to the Llanos de Anzoátegui.
- Phase 3 (1936-1960) - International Investment Boom: The influx of international capital and technological advancements in Venezuela during the mid-20th century led to a surge in large-scale exploration, resulting in significant oil discoveries. Seismic surveys and extensive drilling campaigns characterized this period of rapid expansion. Since 1940, exploration has focused on the Oficina–type Miocene sand play in antithetic fault blocks from productive trends in the Guárico and Maturin sub-basins. This play emerged as a medium and light oil source, with API gravity ranging between 25° and 40°. During the 1960s to 1990s, these fields, e.g., Oficina, Jobo, Dación, Oritupano, Limón, etc., remained among the most productive in Venezuela, benefiting from relatively straightforward extraction methods and high profitability due to the ease of refining medium and light crude oil, making them highly valuable to the country's oil industry. In the early 1950's, the trend of inverted structures of the Anaco gas Miocene play was discovered. A giant gas discovery was also made in the Yucal-Placer stratigraphic play in the Paleogene sands. The Hydrocarbon Law of 1943 marked a turning point, as the Venezuelan government began asserting greater control over its oil resources by raising taxes and royalties on foreign companies. After World War II, global oil demand skyrocketed, positioning Venezuela as one of the world's leading oil exporters. Meanwhile, nationalist sentiment grew in the 1950s and 1960s, with increasing calls for state control of the oil industry, culminating in President Rómulo Betancourt's push for more state participation in oil ventures during his tenure in the 1960s.
- Phase 4 (1960-1977) – pre-Nationalization: As Venezuela geared up for the nationalization of its oil industry, exploration activities significantly slowed, with the focus shifting to maintaining production from existing medium-light oil fields. While discoveries became less frequent, the country relied on its established reserves to sustain output, and exploration in the Eastern Venezuela Basin remained after the Oficina-type play.
- Phase 5 (1977-1995) - Nationalization & Major Discoveries: After the nationalization of Venezuela's oil industry in 1976, PDVSA assumed control and in the EVB focused initially on the Orinoco Oil Belt, la Faja Petrolífera del Orinoco. Thus, in the 1980s, exploration was completed for the super-giant Orinoco Oil Belt of heavy and extra-heavy oils in an extensive stratigraphic Miocene play wedged against the Guayana craton, setting the stage for subsequent advances in oil recovery techniques and a downstream industrial current of oil upgraders in the Anzoátegui coast on the Caribbean. Further to the north in the Maturin sub-basin, exploration involved in the 1980s and 1990s Furrial-type Paleogene and Cretaceous thrust plays along the southern flank of the Serranía Oriental, deep below the shallow stratigraphic traps, aided by advancements in seismic technology. The discovery of thrust front play boosted the country's production in the '80s and 1990s. This period saw a strategic shift in exploration, with an increasing focus on tapping heavy oil reserves and exploring offshore fields. During the 1980s and 1990s, PDVSA grew into one of the world's largest and most successful state-owned oil companies, pioneering new technologies and maintaining partnerships with international partners. This era cemented PDVSA's leadership in the global oil industry.
- Phase 6 (1995-2000) - Apertura and Chávez Era: During the Apertura Petrolera in the 1990s, PDVSA invited foreign investment to develop Venezuela's mature fields and boost production. This era saw substantial investment in oil and gas, with international oil companies partnering with PDVSA under more favorable terms to modernize infrastructure and introduce advanced technologies. Production surged, making Venezuela a more prominent global oil producer. Exploration in the EVB under PSC contracts led to additional discoveries in the thrust front play in Oligocene and Cretaceous sandstones, e.g., Pirital and Jusepin Deep.
However, political instability under President Hugo Chávez, particularly in the early 2000s, led to national strikes and disruptions in the sector. The shift toward renationalization involved the creation of Empresas Mixtas, joint ventures between PDVSA and international oil companies. This aimed to maintain foreign participation while increasing state control. Despite this, mismanagement and shifting policies undermined production growth, stalling the momentum gained during the Apertura and discouraging further foreign investment in the long term.
The undiscovered oil reserves in the Eastern Venezuelan Basin to the east, merging the Orinoco Delta offshore and the Guyana Basin, have been subject to various estimates based on geological studies, seismic data, and recent exploration activity. While it's difficult to pinpoint exact figures, here is a breakdown of these regions' expected undiscovered light oil reserves.
The U.S. Geological Survey (USGS) estimated in 2009 that the onshore Eastern Venezuelan Basin (EVB) could contain between 2 to 4 billion barrels of undiscovered conventional oil resources, primarily light and medium grades. In contrast, the offshore Orinoco Delta, which has received less exploration attention than its onshore counterparts, is believed to hold an estimated 5 to10 billion barrels of undiscovered oil resources, with a significant portion likely to be light oil. However, these estimates highlight the geological challenges currently faced in understanding the EVB's complex geology, particularly its relationship with the Guyana Basin and the southern border of the Caribbean Plate. Additionally, the influence of the Orinoco River as a significant sediment fairway complicates the geological landscape, necessitating a more nuanced exploration of play-based distributions and the region's upside potential. Enhanced geological knowledge is critical for unlocking the full resource potential in this promising basin.
In the past 20 years, advances in geology and geophysical technology have revolutionized exploration and production in many basins in the world. These improvements have led to more precise imaging of subsurface structures, better identification of hydrocarbon reservoirs and petroleum systems and optimization of exploration strategies. In the EVB, these advances are waiting to be capitalized in the context of renewed E&P activity after more than ten years of stagnant E&P activities.
About U3 EXPLORE Venezuela Project
The U3 Explore Venezuela Project, initiated by U3 Explore and Actus Veritas Geoscience, is a pioneering effort to preserve and digitally consolidate Venezuela's extensive geological knowledge. Since its founding in 2019, the project has focused on gathering, validating, and classifying public information into a structured, contextual format to ensure this valuable data is maintained for future generations. The initiative aims to evolve into a Sustainable Development Data Center (SDDC),envisioned as a comprehensive digital hub that centralizes knowledge on Venezuela's natural resources, supporting the country's energy and environmental sectors.
For 2024-2025, the project sets key goals for those who are interested in subscribing:
- Securing Ownership and Funding: Establishing sustainable financial management to ensure the project's long-term viability, focusing on the company's goals.
- We are delivering Peer-Reviewed Insights and collaborating with global experts to validate and enhance the quality of datasets.
- Mentorship and Collaboration: Building partnerships across Venezuela's energy industry to foster innovation and knowledge sharing
- Aligning with Sustainable Practices: Integrating strategies that align with global efforts toward low-carbon solutions and energy transitions.
Through the U3D Web Application available by subscription and U3 Explore Venezuela projects, which include the geospatial digitalization of the basins, fields, and reservoirs of Venezuela, our team aims to reduce uncertainty in investment in onshore and offshore projects of production and exploration for oil and gas, help to optimize hydrocarbon recovery and contribute to the revitalization of Venezuela's energy sector while supporting decarbonization efforts and improvements in information management required for informed business decisions.
Our new CAMGOM Consortium links the tectonic evolution of the margin and the development of Petroleum systems. It is available for new subscribers and will provide participants with an innovative tectonic and geological framework for realistic statistical analysis of all the basins in the region. We started withthe basins along the southern margin of the Caribbean Plate and the adjacent northern South American plate. The Project results will be accessible online through a GIS portal and presented as maps and reports for key tectonostratigraphic intervals.
References
- Arminio, J. F.,, 2020, Virtual Live Discussion: Calculating Resource Potential of Maracaibo and Eastern Venezuelan Basins, U3 EXPLORE.
- Christopher D. French and Christopher J. Schenk, 2004, Map Service Showing Geology, Oil and Gas Fields, and Geologic Provinces of the Caribbean Region, USDI - USGS Open-File Report 97-470-k.
- Galea, F., 2020, Eastern Venezuela Basin, U3 Explore presentation pdf available by subscription.
- Global Energy Monitor, 2024, Energy Profile: Venezuela, Retrieved July 13, 2024, https://www.gem.wiki/Energy_profile:_Venezuela.
- International Energy Agency (IEA), 2020, IEA Venezuela Report.
- Ministerio de Energía y Minas, 1997, Léxico Estratigráfico de Venezuela (digital version).
- PDVSA, 2007, Informe de Gestión 2007, Retrieved February 15, 2024, http://www.pdvsa.com/images/pdf/IGA2007.pdf.
- PDVSA, 2014, Codificación de Proyectos y sus Documentos: Capítulo 3 Planificación de Proyectos, PDVSA #PIC-01-03-05, 65 p., Retrieved March 4, 2024, https://pdfcoffee.com/pic010305-pdf-free.html
- PDVSA, 2016, Informe de Gestión 2016, Retrieved February 24, 2024, http://www.pdvsa.com/images/pdf/Inversionistas/INFORMEDEGESTION2016.pdf
- PDVSA, 2020, Propuesta de Reestructuración, Presentation, Retrieved July 27, 2023, https://petroleumag.com/pdvsa-propuesta-de-reestruccturacion/
- Petróleo y Otros Datos Estadísticos (PODE), 2014 (PDF), Archived from the original on November 11, 2022.
- PETRÓLEOS DE VENEZUELA, S.A., 2016, EX-99.T3, U.S. Securities and Exchange Commission, Retrieved July 13, 2024, https://www.sec.gov/Archives/edgar/data/906424/000119312516712239/d171369dex99t3e.htm
- Sandrea, R., & Essenfeld, M., 2021, The Future of Venezuela's Oil Industry, Eprinc, Archived from the original on December 18, 2023, Retrieved May 8, 2024, https://eprinc.org/wp-content/uploads/2021/09/The-Future-of-Venezuela%E2%80%99s-Oil-Industry.pdf
