Big conference, spectacular setting

Conjugate Margins Are (Again) in the Spotlight

Outcrop of Tithonian fluvio-deltaic deposits, 60 kilometers north of Lisbon, Portugal – one of the best reservoir-rocks of the Lusitanian Basin and a good analog to the North Sea’s Statfjord Formation. 
Photos courtesy of Nuno Pimentel
Outcrop of Tithonian fluvio-deltaic deposits, 60 kilometers north of Lisbon, Portugal – one of the best reservoir-rocks of the Lusitanian Basin and a good analog to the North Sea’s Statfjord Formation. Photos courtesy of Nuno Pimentel

Commercial discoveries on conjugate sides of the North and Central Atlantic margins are propelling an industry renaissance in the multi-disciplinary study of plate tectonics, petroleum systems, and source rock mapping.

A multi-year, scientific focus on the vast potential of these economically significant passive margins continues this fall, in a spectacularly beautiful setting.

The second Central and North Atlantic Conjugate Margins Conference – co-sponsored by AAPG and AAPG’s European Region, among others – will be held Sept. 29-Oct. 1 in Lisbon, Portugal.

In addition to attending technical sessions, participants will have numerous opportunities for some hands-on experience, whether viewing core or travelling to classical geological outcrops in Portugal and Morocco.

In the Lusitanian Basin, for example, geologists will be able to touch Jurassic age salt diapers that have pierced through overlying sediments, dragging them upwards and creating textbook-style traps for oil and gas.

Used in conjunction with seismic data and wireline logs, Portugal’s outcrops illustrate the geodynamic and tectono-sedimentary history related to the opening and closing of the Atlantic and Tethys Oceans, respectively.

Nuno Pimentel
Nuno Pimentel

“The study of Portugal’s outcropping stratigraphy, salt tectonics and associated oil shows allows a better understanding of the petroleum systems of the basin, and provides a better prediction of what may be expected in the deep offshore where intense exploration is going on at the moment,” said AAPG member Nuno Pimentel, co-chair of Lisbon 2010.

According to Pimentel, an assistant professor of geology at the University of Lisbon, most of the dozens of wells drilled onshore have targeted Portugal’s diapiric structures.

Geoscientists studying coastal and deltaic Oxfordian marls and sandy clays, 80 kilometers north of Lisbon. These prograding siliciclastics underline the intense subsidence and infill related to the Late Jurassic rifting at the Lusitanian Basin, coeval with the conjugated Jeanne D’Arc Basin.
Geoscientists studying coastal and deltaic Oxfordian marls and sandy clays, 80 kilometers north of Lisbon. These prograding siliciclastics underline the intense subsidence and infill related to the Late Jurassic rifting at the Lusitanian Basin, coeval with the conjugated Jeanne D’Arc Basin.

Although unsuccessful, many of the wells contained oil shows.

“Understanding the evolution of the Central and North Atlantic conjugate margins,” Primental said, “is essential to defining the petroleum systems and the oil and gas potential of these promising regions.”

Lisbon 2010’s theme, “Rediscovering the Atlantic: New Winds for an Old Sea,” has been designed to enhance the E&P industry’s knowledge – and opportunities – in these passive margin basins.

“The oil and gas potential of Portugal’s conjugate margin is virtually unexplored,” Pimentel said. “Yet, we’re facing Newfoundland and Nova Scotia, so why not?

“We hope this conference will contribute to putting Portugal on the map of the oil and gas basins of the North Atlantic.”

Building On Success

Although steeped in a long E&P history, Portugal’s oil and gas industry is still in its infancy. During the 20th century, 50 wells were drilled onshore and a dozen offshore (primarily in the 1970s, in waters less than 200 meters), yiedling several oil and gas shows but no commerical discoveries.

A recent regional multi-client seismic data program in Portugal’s deep waters, however, precipitated a renewed interest in Portugal’s offshore, leading to the signing of several exploration concessions.

Lisbon 2010 will provide an international forum for researchers and industry to share geoscience knowledge focusing on the Central and North Atlantic passive margins via sessions built on three themes:

  • Evolution of Atlantic Margins.
  • Atlantic Petroleum Systems.
  • Atlantic Margins E&P.

Two-day short courses will be offered by internationally renowned specialists Octavian Catuneanu (University of Alberta, Canada), who will present sequence stratigraphy and its application to petroleum exploration and production, and Mateu Estebán (Carbonates International, Spain), who will present a multi-scale approach to understanding carbonate reservoirs and related play types.

A post-conference field trip will head to Morocco to study Triassic to Cretaceous age outrcops of the the Agadir and Essaouira basins – including some equivalents to the oil and gas producing reservoirs in offshore Nova Scotia.

Lisbon 2010 will be building on the successes and momentum of two previous conjugate margin conferences co-sponsored by AAPG – a 2007 meeting in Marrakesh, Morocco and a 2008 session in Halifax, Nova Scotia (see January 2008 EXPLORER).

Highly successful, the Halifax “Central Atlantic Conjugate Margins Conference” boasted over 200 delegates from 17 nations, representing 48 companies and 26 government and academic institutions. More than 90 technical oral and poster papers were presented.

Dave Brown, the Halifax co-chair, was pleased to pass the baton across the Atlantic to Pimentel and Rui Pena dos Reis, the co-chairs of Lisbon 2010.

“A regional and thematic-focused conference benefits from the continuity of meeting on a scheduled basis,” said Brown, an AAPG member and senior geologist with the Canada-Nova Scotia Offshore Petroleum Board. “Coming together every two to three years provides a reasonable period to collect new data and to develop new ideas, encouraging collaboration and facilitating joint projects and initiatives.

“Interestingly, exploration on opposing conjugate basins is imbalanced,” Brown added. “Relatively speaking, there are a greater number of wells, seismic, discoveries and fields on the Brazilian, Nova Scotian and Newfoundland margins than their conjugates in Angola, Morocco and Iberia and Ireland, respectively.

“There are a number of varied reasons for this,” he said, “many of which are not geological.”

Jurassic Parkway?

Michael Enachescu, one of Lisbon 2010’s keynote speakers, will deliever an address on “Late Jurassic Source Rock Super-Highway on Conjugate Margins of the North and Central Atlantic (offshore East Coast Canada, Ireland, Portugal, Spain and Morocco).” Mapping the distribution of the Kimmeridgian-age source rock, Enachescu, said, is the key to exploration success in the Atlantic passive margins.

“Find me the pre-rift, intra-continental system that was filled, from time to time, with a Jurassic sea,” he said. “Map it, determine whether it survived and whether it’s mature.”

Enachescu, an AAPG member, is the chief geophysicst at Calgary-based MGM Energy Corporation, and an adjunct professor at Memorial University’s Department of Earth Sciences in St. John’s, Newfoundland.

He’s dedicated the past 30 years of his career to evaluating the oil and gas potential Canada’s East Coast frontiers, looking for “ponds where the source rock is preserved.”

He’s also promoting a three-step research program – to be undertaken by a coordinated international initiative – to accomplish the following tasks:

  • Reconstruct the paleogeography of the intra-continental rifting in the north and oceanic rifting in the south.
  • Identify and map, with regional seismic grids and geochemical well results, the Late Jurassic source rock super-highway.
  • Characterize and connect source rocks to crude oil in discoveries and shows, correlating along and across the Atlantic margins.

Discrete portions of the three-step research program, he said, already have been kicked off by various international government agencies and consulting groups. The research results, he said, will enable geoscientists from Ireland, Spain, Portugal and Morocco to connect their data points to Canadian data points.

"These geoscientists are keen to collaborate and learn because, up to now, the Canadian side is the only successful North and Central Atlantic Conjugate Margins,” he said.

Today, 350,000 barrels per day are produced from three oil fields in the Jeanne d'Arc Basin offshore Newfoundland, while 450 million cubic feet flow daily from five gas fields located in the Sable sub-basin, offshore Nova Scotia.

Additional developments are under construction in the Canadian frontiers: the giant Hebron oilfield offshore Newfoundland, and the large Deep Panuke gasfield offshore Nova Scotia.

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The Bond Remains Strong

Situated on opposite sides of the Atlantic Ocean, Portugal and Brazil are connected by more than 500 years of a common history, culture and language.

The two nations also are connected by a common economic interest in the oil and gas potential of their respective continental margins. Just as the Old World transported its culture and traditions to Brazil, today’s New World Brazilian geologists travel to Portugal to study the evolution of the Central Atlantic’s conjugate margin, a tectonic history illustrated by spectacular outcrops, ranging in age from Triassic to Cretaceous.

For several years, Nuno Pimentel and Pena dos Reis have led geological field trips for Petrobras, Brazil’s state oil company, using Portugal’s Lusitanian Basin outcrops as their Old World analogs.

Portugal’s “Natural Oil Triangle,” AAPG member Pimentel said, lies between two giants: Brazil and Angola. All three countries are linked by a common history, culture and language.

“There is a strong feeling of friendship between Brazil and Portugal,” said AAPG member Mario Carminatti, Petrobras’ executive manager of exploration. “The two countries feel like two close friends who have been separated for a while. In our case, the separation distance is defined exactly by the formation of the Atlantic Ocean and its marginal basins!

“Even though the timing and the details of Portuguese conjugate basins differ from those in Brazil,” Carminatti added, “the general process of formation of marginal basins shares many similarities.”

Buoyed by offshore exploration successes in Brazil’s conjugate margin – the Tupi field with eight billion barrels of oil equivalent in place – and encouraged by similar geological histories and mechanisms in the Lusitanian Basin, Petrobras recently picked up offshore exploration licenses in Portugal with commitments ranging from 2-D and 3-D seismic data acquisition to the drilling of exploratory wells.

“We consider these licenses as an important new frontier to be explored in the coming years,” Carminatti said. “In spite of the natural geological risks, we consider that the prospectivity of these areas presents an enormous potential to be assessed.”

“Portugal discovered Brazil 500 years ago, and now Brazil is helping Portugal discover oil in the 21st century,” Pimentel said.

Recognizing significant value in these intimate, trans-Atlantic conjugate margin conferences, Petrobras sponsored Halifax 2008 and is a Diamond sponsor for Lisbon 2010. According to Carminatti, the conference format – there are no concurrent sessions, so attendees don’t have to choose between talks – provides excellent opportunities to meet the top specialists on the studies of continental break-up, basin formation and ocean spreading, both from academia and oil companies.

“It’s like having a crash course on some of the hottest topics in marginal basins with the best specialists, in person!”

- SUSAN R. EATON