Solving the Mystery of Angolan Oil

It was a milestone year for everyone living in Angola. In 2002, Jonas Savimbi, the leader of the rebel group UNITA, was killed on Feb. 22 that year, bringing an abrupt end to the long and horrible 27 years civil war.

Suddenly it was possible to leave Luanda and travel in the countryside, something that was much too dangerous during the war years.

But before I embark on this story, first I must briefly explain how I ended up in Angola.

I’ve been living and working in Luanda, the capital city of Angola, since 1995. Unquestionably, 17 years is a long time for an expatriate to stay in one place, especially in a not-so-easy country like Angola, which is still recovering from a civil war.

In 2002 I retired from Chevron as a Texaco-legacy employee after 30 years of service worldwide in technical and management positions. The retirement occurred while I was living in Luanda, and rather than returning home to Canada, my wife, Henriette, and I decided to stay on in Angola.

Why stay longer? We like the people, and it is a place where one can “make a difference.”

In 2003 I became the in-country consultant for Tullow Oil, and at the same time served as country representative for a Norwegian humanitarian organization, Yme Foundation, which was drilling water wells in northern Angola. In 2010 I became a consultant for Gaffney, Cline & Associates in Luanda.

While working for Texaco, I heard rumors about some oil seeps located north of Luanda. I read copies of some old records, which indicated that as early as the 1700s Portuguese explorers found oil seeps and asphalt deposits exposed at Libongos, about 60 kilometers northeast of Luanda. These are located along the outcrop edge of the Pre-Cambrian granites, which mark the eastern edge of the Kwanza sedimentary basin.

In 1820, 34 barrels of “bitumen” were shipped to Rio de Janeiro to be used as caulking to prevent ships from leaking. When the Portuguese explorer J.C. Monteiro was in Angola from 1855 to 1866, he described various seeps along the coast; other explorers mentioned the existence of “petroleum springs” they witnessed in the country.

I found this to be highly intriguing, but due to the war, travel outside of the city of Luanda was strictly off limits. When the war ended and the countryside slowly opened up, I finally saw for myself the Libongos oil seeps. That was mid-2003, and soon I started leading geological field trips there on a regular basis.

The field trip participants were not just geologists, but also engineers, economists, diplomats, university students and other non-industry types. I developed a geological familiarity with the area, perhaps better than anyone else in the country, since I was making repeated visits there.

A Challenge Accepted

2005 was the 30th anniversary of Angola’s state oil company, Sonangol. The editor of Sonangol’s corporate magazine, Universo, heard that I was leading geological field trips outside of Luanda and he challenged me to find the evidence of the first-ever drilling for oil in Angola.

Fortunately, AAPG member Mario Brandao, an Angolan geologist working for Sonangol who passed away in 2011, gave me photocopies of some bits and pieces of historic information about this drilling.

Brandao was a walking encyclopedia of information about Angolan geology, and the information I received from him indicated that the first-ever drilling was in 1915 – almost 100 years ago, about 15 kilometers inland from the Atlantic Ocean along the small Dande River, 30 kilometers northeast of Luanda.

I was pessimistic about finding any evidence of the drilling, since the information was so limited.

The records included a table summarizing the first drilling in Angola. In 1915, the Portuguese oil company Companhia de Pesquisas Mineiras de Angola (PEMA), drilled the first exploration well, which was called Dande-1. It went to a depth of 602 meters, and 13 wells were thereafter drilled – eight of which were drilled in the valley of the Dande River.

The records do not indicate why this area was targeted by PEMA. Seismic technology had not yet been developed, so perhaps they had mapped out an anticline based on surface geological mapping.

What I found to be extremely interesting was that one of the wells, Dande-4, drilled in 1916, was reported to have been drilled to a depth of 857 meters and flowed “Oleo denso, ¾ bl/12h; 850.6 – 857 m, recuper 6 bbls/dia,” meaning the well flowed at six barrels of dense oil per day.

Brandao also provided me with information that in 1919, a Portuguese oil company, COPA (Companhia do Petroleo de Angola), was created in association with Sinclair Consolidated Oil, an American company, to explore in the north along the Congo River.

The American geologist who was contracted as exploration manager for Sinclair in Angola was Kessack Duke White, who went by ship from New York to Lisbon and then transferred to a ship to Luanda carrying Portuguese military prisoners.

White later wrote, “The entire trip required only one month, which was not bad.”

Another American geologist, Chester Washburne, started a geological investigation in 1921 in a vast part of western Angola, which led to a drilling program of 21 wells. The reports indicated “the results were not very successful.”

The concessionary contract with Sinclair ended in 1932, and that marked the end of the first phase of the Angola petroleum exploration.

The Search Begins

Spurred on by the challenge to discover the first-ever drilling, in June 2005 I rounded up some friends and headed to the Dande River valley to find evidence of the drilling. Thank goodness we had strong four-wheel drives since the roads soon deteriorated into narrow tracks.

We were expecting to find nothing due to the passage of so much time. One hundred years of exposure to a hot tropical environment like Angola had probably destroyed all evidence of drilling, such as wellheads.

As we drove along we asked local people in small settlements we passed through if they knew anything about the drilling in the area 100 years ago. You could sense them asking themselves why are these people looking for something that happened 100 years ago? I am sure some thought we were crazy.

At the same time we would ask in Portuguese, “Existem minas aqui?” meaning, “Are there landmines here?” We wanted to be sure that we were not driving through minefields laid down during the war.

Our luck changed, however, along the south bank of the Dande River, where we met Chico Fonseca, the administrator of the village of Catanga, and his colleague, Jose Nelito. We asked them if they knew anything about wells drilled by the Portuguese almost 100 years ago.

I was dumbstruck when Fonseca nodded and said, “Yes, we will take you there.”

He and Nelito climbed into our cars and we drove for a few kilometers, then hiked through a bit of jungle toward the river when he announced, “There it is.”

I was absolutely amazed to see an oil-covered pipe sticking up from the riverbank opposite us.

Fonseca then disappeared and returned with an old dugout canoe. As he paddled us across the river he casually mentioned that there were crocodiles in the river, but he assured me, “Don’t worry, they only attack dogs and not people.”

When I clambered out of the canoe and onto the river bank, I realized that I was looking at wide diameter casing sticking about two meters high above the river bank, full of heavy oil with a small amount dripping down the outside of the casing. The oil was dense and tar-like, probably due to biodegradation of the lighter components. I concluded that I was looking at Dande-4.

Of the eight wells that had been drilled in the Dande River valley, none except for Dande-4 was reported to have found oil. That meant I was looking at Dande-4, the first well in Angola to have actually tested a flow of oil.

In 1916 cementing and plugging of wells would have been rudimentary technology, so likely the well had not been properly plugged off. I also concluded that the continuous, very slow flow of heavy oil both inside and outside of the casing probably helped preserve the wellhead from the effects of a century of tropical weathering.

Standing and looking at the wellhead gave me a rush of emotions. It was like going back a century in time – I imagined these now long-forgotten pioneers drilling here in the first serious attempt to find oil in Angola. The conditions would have been extremely difficult due to the heat, humidity and the ever-present threat of malaria and other tropical diseases, plus a possibly hostile local population.

I envisioned these long-forgotten engineers, geologists, drillers, roustabouts and roughnecks as they wrestled with their primitive rig in the wild bush – and I am sure that many men, both Portuguese and Angolan, died in this effort. These early explorers for oil truly were heroes having worked so far away from home and under such difficult conditions.

Bonus Discovery

But the story does not end there.

While crossing back to the south bank of the Dande River, I remembered I also had with me a good Petro-Consultants well-base map of the Kwanza Basin, showing that in 1974, Compagnie Francaise des Pétroles (CFP) the forerunner of Total Petroleum, had drilled a well, Catanga-1, to a depth of 1,408 meters on the south bank of the Dande River.

Likely CFP was trying to intersect the same oil zone found in the nearby Dande-4.

When I mentioned this to Mr. Fonseca, he said that although he was only 10 years old at the time, he remembered the well drilled by the French. Not far from the shore he located the drill site, now overgrown by trees but with a small depression where the rig had been located.

The records show that Catanga-1 was plugged and abandoned; Fonseca remembered that the drillers were in a big rush to get the rig out because it was the rainy season and the river was already overflowing its banks.

I thought that perhaps there was another reason why the rig left so quickly – it may have been because Catanga-1 was drilled just one year before Angola’s independence from Portugal in 1975. The military regime in Lisbon was overthrown in the Carnation Revolution in 1974, and the new government had announced that in 1975 Angola would cease being a Portuguese colony and be given independence.

There was a lot of political uncertainty in Angola, with various political parties fighting to head up the government at independence – so maybe CFP was in a big hurry to get their rig out of Angola to a safer location.

The Next Chapter?

Today Angola produces almost two million barrels of oil per day. With the exception of 10,000 barrels of oil per day currently being produced near the town of Soyo in northern Angola, Angola’s oil production is entirely offshore.

But perhaps the story of Dande-4 is not yet finished. Perhaps someday, Angola will follow suit and build an oil museum at Dande-4 like the oil discovery site of Titusville in Pennsylvania, where Colonel Drake drilled the first oil discovery well in the United States; or like the historic site near the town of Leduc, Canada, commemorating the 1947 discovery of major oil reserves in Devonian reefs that catapulted Canada into becoming a major oil producing nation.

In the meantime, I continue to lead field trips to the Barra do Dande area to acquaint people with the interesting geology and to teach them about Angola’s fascinating petroleum heritage.

Comments (0)


Historical Highlights - Tako Koning

Tako Koning, an AAPG Public Service Award winner, is a 33-year member of AAPG and is a long time resident of Angola where he currently works as a consultant for Gaffney, Cline & Associates. He also continues as a part-time (volunteer) Residential Representative for the Norwegian NGO, Yme Foundation, which drills wells for drinking water in rural areas of Cabinda province, Angola. He has attended all three DOWAC’s (2004, 2007, 2010) and views attendance at the DOWAC’s as a “must” for anyone involved in West Africa exploration and production.

Historical Highlights

Historical Highlights - Hans Krause

Hans Krause is an AAPG Honorary Member, Distinguished Service Award winner and former chair of the AAPG History of Petroleum Geology Committee.

Historical Highlights

A History-Based Series, Historical Highlights is an ongoing EXPLORER series that celebrates the "eureka" moments of petroleum geology, the rise of key concepts, the discoveries that made a difference, the perseverance and ingenuity of our colleagues – and/or their luck! – through stories that emphasize the anecdotes, the good yarns and the human interest side of our E&P profession. If you have such a story – and who doesn't? – and you'd like to share it with your fellow AAPG members, contact the editor.

View column archives

Image Gallery

See Also: Bulletin Article

The origin of thermogenic natural gas in the shallow stratigraphy of northeastern Pennsylvania is associated, in part, with interbedded coal identified in numerous outcrops of the Upper Devonian Catskill and Lock Haven Formations. Historically documented and newly identified locations of Upper Devonian coal stringers are shown to be widespread, both laterally across the region and vertically throughout the stratigraphic section of the Catskill and Lock Haven Formations. Coal samples exhibited considerable gas source potential with total organic carbon as high as 44.40% by weight, with a mean of 13.66% for 23 sample locations analyzed. Upper Devonian coal is thermogenically mature; calculated vitrinite reflectances range from 1.25% to 2.89%, with most samples falling within the dry-gas window. Source potential is further supported by gas shows observed while drilling through shallow, identifiable coal horizons, which are at times located within fresh groundwater aquifers. Thermogenic gas detected in area water wells during predrill baseline sampling is determined not only to be naturally occurring, but also common in the region.

Desktop /Portals/0/PackFlashItemImages/WebReady/geologic-and-baseline-groundwater-evidence-for.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 5776 Bulletin Article

Criteria for recognizing stratigraphic sequences are well established on continental margins but more challenging to apply in basinal settings. We report an investigation of the Upper Devonian Woodford Shale, Permian Basin, west Texas based on a set of four long cores, identifying sea level cycles and stratigraphic sequences in an organic-rich shale.

The Woodford Shale is dominated by organic-rich mudstone, sharply overlain by a bioturbated organic-poor mudstone that is consistent with a second-order eustatic sea level fall. Interbedded with the organic-rich mudstone are carbonate beds, chert beds, and radiolarian laminae, all interpreted as sediment gravity-flow deposits. Bundles of interbedded mudstone and carbonate beds alternate with intervals of organic-rich mudstone and thin radiolaria-rich laminae, defining a 5–10 m (16–33 ft)-thick third-order cyclicity. The former are interpreted to represent highstand systems tracts, whereas the latter are interpreted as representing falling stage, lowstand, and transgressive systems tracts. Carbonate beds predominate in the lower Woodford section, associated with highstand shedding at a second-order scale; chert beds predominate in the upper Woodford section, responding to the second-order lowstand.

Additional variability is introduced by geographic position. Wells nearest the western margin of the basin have the greatest concentration of carbonate beds caused by proximity to a carbonate platform. A well near the southern margin has the greatest concentration of chert beds, resulting from shedding of biogenic silica from a southern source. A well in the basin center has little chert and carbonate; here, third-order sea level cycles were primarily reflected in the stratigraphic distribution of radiolarian-rich laminae.

Desktop /Portals/0/PackFlashItemImages/WebReady/a-sequence-stratigraphic-framework-for-the-Upper-Devonian-Woodford-Shale.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 3250 Bulletin Article

The central Black Sea Basin of Turkey is filled by more than 9 km (6 mi) of Upper Triassic to Holocene sedimentary and volcanic rocks. The basin has a complex history, having evolved from a rift basin to an arc basin and finally having become a retroarc foreland basin. The Upper Triassic–Lower Jurassic Akgol and Lower Cretaceous Cağlayan Formations have a poor to good hydrocarbon source rock potential, and the middle Eocene Kusuri Formation has a limited hydrocarbon source rock potential. The basin has oil and gas seeps. Many large structures associated with extensional and compressional tectonics, which could be traps for hydrocarbon accumulations, exist.

Fifteen onshore and three offshore exploration wells were drilled in the central Black Sea Basin, but none of them had commercial quantities of hydrocarbons. The assessment of these drilling results suggests that many wells were drilled near the Ekinveren, Erikli, and Ballıfakı thrusts, where structures are complex and oil and gas seeps are common. Many wells were not drilled deep enough to test the potential carbonate and clastic reservoirs of the İnaltı and Cağlayan Formations because these intervals are locally buried by as much as 5 km (3 mi) of sedimentary and volcanic rocks. No wells have tested prospective structures in the north and east where the prospective İnalti and Cağlayan Formations are not as deeply buried. Untested hydrocarbons may exist in this area.

Desktop /Portals/0/PackFlashItemImages/WebReady/new-evidences-for-the-formation-turkey.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 3705 Bulletin Article

See Also: Energy Policy Blog

During the recent AAPG Congressional Visits Day, staff for the House Natural Resources Committee expressed interest in receiving input on issues and potential legislation from knowledgeable stakeholders. Here is an easy way to get involved in the process of informing Washington, D.C., decision makers: send a quick comment to the committee members in response to a particular hearing.

Desktop /Portals/0/PackFlashItemImages/WebReady/two-house-hearings-on-oil-and-gas-issues-2014-03mar-26.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 12379 Energy Policy Blog

See Also: Field Seminar

Join us on a trip to the Capricorn-Bunker group located around the world-famous Southern Great Barrier Reef.
Desktop /Portals/0/PackFlashItemImages/WebReady/FT8-Geology-of-Heron-Island-hero.jpg?width=50&h=50&mode=crop&anchor=middlecenter&quality=90amp;encoder=freeimage&progressive=true 19061 Field Seminar