Danger, Challenges and Luck in the Putumayo-Napo Basins

From first oil to export in the Amazon Rainforest

I landed in Bogota in June 1963 for employment with Texpet Colombia, the local exploration company of Texaco. At 8,600-feet elevation, I found the city a sometimes cold, damp and somber place after having earlier worked for four years with Kewanee Oil Company of Tulsa in sunny Havana, Cuba.

A couple days later, while I was going through orientation in the Texpet office, the news broke that Orito-1, the first wildcat drilled on a 3.5 million-acre concession (held 50/50 with Gulf Oil) in the Putumayo jungle, came in at 1,600 barrels of oil per day with total depth of 6,443 feet. The well tested oil (32.0 API) from sandstones of the Caballos Formation (Hollin in Ecuador) in addition to oil from sands in the overlying Villeta Formation (Napo in Ecuador), both Cretaceous. This was the first discovery of oil east of the Andes in the almost 1,500-mile stretch between the Barinas Basin in Venezuela and central Peru. A spontaneous office party ensued, celebrated with shots of the popular aguardiente Cristal to warm things up. This find was only the start of the company’s good luck in the challenging Amazon jungles of Colombia and eastern Ecuador, known as the Oriente.

Putumayo Basin Exploration

Exploration of the asymmetrical Putumayo sub-Andean Basin (with basement rocks of the Guyana shield shallowing to the east) had begun in the 1940s when Texpet sent exploration geologists, traveling by canoe, to document any surface outcrops, with supplies provided by airplane drops. Geologist Don McGirk found evidence of an anticline at Orito, but the area was still too remote for further exploration.

Ten years later, Texpet drilled some two dozen core wells without finding oil. Then, in 1962, exploration picked up and the company moved a houseboat from the Amazon up the Rio Putumayo to a site upstream from the small, remote river town of Puerto Asis. At the end of a gravel road that was built during the Colombian/Peruvian War in 1932, this was the only settlement for miles around. The boat became the Texaco base camp called Santa Ana and a heliport was constructed.

In early 1963, a land-rig from Peru was brought up the Rio Putumayo to Santa Ana by barge. After disassembly, it was dragged by tractors, piece by piece, for three months and some 35 miles along a machete-cleared trail through dense jungle to the Orito-1 drillsite, located on a faulted north-south anticline. After this difficult operation, Texpet decided that future wildcat drilling would use two heli-rigs, which Loffland Brothers Drilling shipped to the Pacific port of Buenaventura and trucked over the Andes to Santa Ana, then flown to the drill sites by Helicol (an Avianca helicopter subsidiary).

Four Bell 204 choppers, with load lifting capacity of 4,000 pounds, were put into service. Some well site moves required 700 flights, carrying living quarters, tractors, drill pipes, field geologists like me, and more. The heli-operation was said to be the largest in the world after Vietnam, and news stories appeared everywhere.

Image Caption

Cofan men at Ambrose camp on Rio San Miguel in 1965

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I landed in Bogota in June 1963 for employment with Texpet Colombia, the local exploration company of Texaco. At 8,600-feet elevation, I found the city a sometimes cold, damp and somber place after having earlier worked for four years with Kewanee Oil Company of Tulsa in sunny Havana, Cuba.

A couple days later, while I was going through orientation in the Texpet office, the news broke that Orito-1, the first wildcat drilled on a 3.5 million-acre concession (held 50/50 with Gulf Oil) in the Putumayo jungle, came in at 1,600 barrels of oil per day with total depth of 6,443 feet. The well tested oil (32.0 API) from sandstones of the Caballos Formation (Hollin in Ecuador) in addition to oil from sands in the overlying Villeta Formation (Napo in Ecuador), both Cretaceous. This was the first discovery of oil east of the Andes in the almost 1,500-mile stretch between the Barinas Basin in Venezuela and central Peru. A spontaneous office party ensued, celebrated with shots of the popular aguardiente Cristal to warm things up. This find was only the start of the company’s good luck in the challenging Amazon jungles of Colombia and eastern Ecuador, known as the Oriente.

Putumayo Basin Exploration

Exploration of the asymmetrical Putumayo sub-Andean Basin (with basement rocks of the Guyana shield shallowing to the east) had begun in the 1940s when Texpet sent exploration geologists, traveling by canoe, to document any surface outcrops, with supplies provided by airplane drops. Geologist Don McGirk found evidence of an anticline at Orito, but the area was still too remote for further exploration.

Ten years later, Texpet drilled some two dozen core wells without finding oil. Then, in 1962, exploration picked up and the company moved a houseboat from the Amazon up the Rio Putumayo to a site upstream from the small, remote river town of Puerto Asis. At the end of a gravel road that was built during the Colombian/Peruvian War in 1932, this was the only settlement for miles around. The boat became the Texaco base camp called Santa Ana and a heliport was constructed.

In early 1963, a land-rig from Peru was brought up the Rio Putumayo to Santa Ana by barge. After disassembly, it was dragged by tractors, piece by piece, for three months and some 35 miles along a machete-cleared trail through dense jungle to the Orito-1 drillsite, located on a faulted north-south anticline. After this difficult operation, Texpet decided that future wildcat drilling would use two heli-rigs, which Loffland Brothers Drilling shipped to the Pacific port of Buenaventura and trucked over the Andes to Santa Ana, then flown to the drill sites by Helicol (an Avianca helicopter subsidiary).

Four Bell 204 choppers, with load lifting capacity of 4,000 pounds, were put into service. Some well site moves required 700 flights, carrying living quarters, tractors, drill pipes, field geologists like me, and more. The heli-operation was said to be the largest in the world after Vietnam, and news stories appeared everywhere.

A September 1966 headline of the Kansas City Star read “Oil Firms Probing Deep Into The Amazon – Biggest Deposit Ever” and included an interview with Capt. Jaime Cuellar, chief pilot of Helicol. Cuellar said, “That’s not all we carry – when the advance camp was open at Orito, the girls from the bordello in town moved right in behind. Texpet called in the police and we flew out three hollerin’ helicopter loads. Two days later the girls had come back up the river to Orito in canoes and set-up ‘business’ in treehouses.”

During 1967, Texpet decided to build a network of roads so land-rigs could drill needed development wells. Earlier, in 1964, a contract was signed with Williams Brothers to manage construction of the 193-mile, 50,000 barrels of oil per day (now 190,000), Trans-Andean pipeline to move oil from Orito over the Andes at 11,540 feet to the Pacific port of Tumaco. Pipeline construction was difficult and dangerous, with deadly helicopter crashes and landslides, especially along the almost vertical east flank of the Andes. The $60 million-line opened in 1969, while Texpet continued to find more oil fields among the Putumayo mountain front structures. In 1980, Ecopetrol, the Colombian state oil company, purchased the entire Texpet assets in the Putumayo – again, the company had good luck, since oil production declined in the 1990s.

Ecuador

After the significant Orito discovery, Texaco-Gulf had the vision to negotiate a 5.2-million-acre concession in the adjacent Oriente area of northeast Ecuador just south of the Rio San Miguel which marks the international border. From 1965–67, the block was evaluated by photo geology, air-magnetometry and seismic, with some surface studies conducted along the mountain front (which in Ecuador is backed by several snowcapped active volcanoes).

In April 1967, after a base camp was hacked out of the pristine jungle, the Lago Agrio 1 wildcat was spudded on a seismic structure and completed for 2,640 BOPD in Cretaceous sandstones with total depth of 10,175 feet. The Napo Formation made 1,241 BOPD at 33.8 API while the Hollin made 1,399 BOPD at 29.3 API. Texaco, again lucky, named the discovery “Sour Lake” (“Lago Agrio” in Spanish), in tribute to the historic Sour Lake Field (1901) near Houston, which launched Texaco. Until the Lago Agrio discovery, Ecuadorian oil production was only about 6,000 BOPD from shallow wells in the Ancon area (1918) on the Pacific Santa Elena peninsula west of Guayaquil.

Napo Basin (Oriente area) oil exploration began in 1931 when Shell started surface studies. From 1946-50, five structures were drilled near the mountain front town of Puyo. All were water-flushed without commercial shows. Why Shell never drilled toward the more prospective Napo Basin axis, which in those days was inhabited by the Auca (now called Huaorani people), is uncertain. As late as January 1956, the Auca were a danger to outsiders, whom they saw as intruders. That month, five Christian missionaries were speared to death after landing in a plane on a sandbar in the Rio Curaray (south of the upper Rio Napo) to make contact with these isolated people. More than 20 years later, in 1977, a seismic crew with Anglo-Ecuadorian Oil was ambushed some miles east at Rio Tiguino, again in Huaorani territory. Maybe Shell was hesitant to operate in this basin axis area, recalling that in the 1940s, a company geologist named Emil Rod was attacked by Aucas near the present tourist town of Misahualli on the upper Rio Napo.

Only a month after the Lago Agrio discovery, Texaco completed its second well – a mountain front wildcat on a surface anticline drilled as Bermejo-1 at TD of only 4,014 feet. The well tested 1,010 BOPD (35.9 API) in the Hollin. Texaco again was very lucky since the anticline was not water-flushed. In January 1969, the company discovered the giant Shushufindi field, which tested 5,117 BOPD from two zones in the Napo Formation, followed in February by equal success at the large Sacha Field.

By 1970, Texaco had developed enough production to begin oil exportation. Work began on the 310-mile Trans-Ecuadorian pipeline (with maximum elevation of 13,400 feet) to the Pacific port of Esmeraldas and was completed in 1972 with a 250,000 BOPD pumping capacity.

Total Oriente oil production was sufficient for Ecuador to petition OPEC for membership, granted in 1973 (Venezuela is the only other OPEC member in the Americas). By 1970, the government forced Texaco to relinquish 50 percent of its acreage. Roads were rapidly being pushed into the rainforest by Texaco and others, which allowed Ecuadorian settlers easy access to free land grants offered by the government to promote colonization of the Oriente. Texaco continued development drilling with land-rigs in its many fields by contractor Parker Drilling until 1992 when it ceased operations in Ecuador. In 2000, Chevron acquired Texaco along with its alleged environmental damage to the Oriente. Since 2013, Petroamazonas (the Ecuadorian state oil company) has been responsible for operations and exploration.

Colombia

In Bogota in late 1963, I was advised by our chief geologist Ken Bishop that I would be assigned to the Putumayo (in 1983, Bishop was kidnapped in Bogota by guerillas and ultimately released for a $1 million ransom from Texaco). I was to manage a geological field party for a six-month detail mapping project along the mountain front near Orito. While surprised, I thought it might be an interesting challenge – as well as a chance to warm-up on the equator.

The assignment became more of an adventure with associated risks than monotonous work in the hot and humid rainforest with some 250 inches of annual rainfall. Once, along with my machete-man, we killed two large venomous Bushmaster snakes – two in one day! When wading shallow streams in search of outcrops, electric eels and fresh water stingrays were ever present. Tent camp sites were always located on the highest stream banks since flash floods could develop within minutes.

Each GFP consisted of an expatriate manager/geologist, an assistant Colombian geologist, surveyor and rodman (to map with plane table and alidade), a camp cook and helper, and a large trocha crew to machete-cut narrow trails to outcrops for sampling. Weekly chopper flights by Helicol delivered food and supplies and provided camp moves. Every two weeks I spent five days in Bogota, then back to the jungle. On one trip the Texpet DC-3 out of Bogota arrived at the city of Florencia airport too late to make my connection on a big Sikorsky helicopter bound for the Putumayo. This time, it wasn’t just the company, but me who was lucky, as that chopper went down in virgin jungle and, tragically, all seven passengers and pilots died.

In 1965, I had another field project in the Putumayo, this time to map the mountain front Churuyaco (with active oil seep producing 1-2 BPOD from the Villeta Formation) and Sucumbios anticlines toward the Rio San Miguel. As Texpet parties had never entered this area since the 1940s, we were visited by the curious but friendly people of the Cofan tribe. They presented me a necklace of colorful parrot feathers and offered “yagé,” also known as “ayahuasca,” a strong hallucinatory drink made from a jungle vine. Three years later the anticlines were drilled as oil field discoveries, so our efforts paid off during those waning years of surface geological studies. I still have a keepsake from that era – my Brunton compass which recorded the strike and dip on those structures.

The Putumayo and the Oriente Today

The Putumayo, now a department of Columbia, has a population of over 350,000, with Puerto Asis still the largest town with some 70,000 residents. The Orito area has around 60,000, having grown from an opening in the jungle with a few drillers 56 years ago in 1963. Over in Ecuador, the population of Sucumbios Province (unattractive Lago Agrio is the capital, officially named Nueva Loja) the population is nearing 200,000 while the entire Oriente has some 750,000 residents. Much of the once pristine rainforest has been clear-cut or is in second growth. Bird life is the most common fauna, with few other wild animals left. In 2003, a second export pipeline (the OCP) was built to the Pacific. Ecuador is still an OPEC member, producing some 530,000 BOPD in 2018.

Putumayo oil production is now minimal, with some Ecuador oil being moved through the Trans-Andean pipeline. Production peaked at about 80,000 BOPD in the early 1980s, of which 66,000 BOPD was produced at Orito. In 2013, a Canadian firm completed Orito-197 for 1,250 BOPD with 80-percent water cut – an indication of the field’s decline. Over the years, the Fuerzas Armadas Revolucionarias de Colombia (FARC) has been active in the Putumayo, including pipeline bombings. In 1992 Orito was attacked by 300 insurgents, killing 26 security police. Now that FARC has mostly given up its arms and is a political party, the Putumayo may become more peaceful.

Several years ago, I again traveled to the Ecuadorian Oriente and paid tribute to the Lago Agrio-1 well site. On any future trip to Colombia, I hope to once more see the Cofan people on the Rio San Miguel where I was given the parrot feather necklace in 1965, a souvenir which I still have from my work in the jungle.

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 Matthew Silverman at silverman_matthew@yahoo.com.

Thomas Ambrose has been an AAPG member since 1952. He is an Oklahoma native who grew up surrounded by wells in the historic Oklahoma City oil field. After service during World War II and earning a bachelor’s degree in petroleum geology from the University of Oklahoma, he entered Rutgers University in New Jersey. Upon earning his master’s degree, he began a career in foreign oil exploration, with corporate assignments in Cuba, Colombia, Ecuador, Indonesia, Trinidad and Tobago, and Singapore. Ambrose also worked as an exploration consultant in other countries and is now retired and living in south Florida. He is a fellow of The Explorers Club, which promotes non-profit exploration, and recently carried the E.C. flag to Cuba (the epicenter of Antillean karst) to document limestone landforms on the island. Ambrose would like to hear from other early contributors to the exploration in the Putumayo/Oriente area at realthora@yahoo.com.