Vaca Muerta

Vaca Muerta shale oil and gas development
Company type	Petroleum exploration and production
Industry	Oil and gas industry
Founded	2010
Headquarters	Argentina
Area served	Neuquén Basin, northern Patagonia, Argentina
Key people	Tomas Garcia Blanco (Repsol-YPF executive who initiated exploration)
Products	Shale oil, shale gas

The Vaca Muerta Formation, whose name translates to dead cow in Spanish, is a geologic unit dating from the Late Jurassic to the Early Cretaceous, situated within the Neuquén Basin of northern Patagonia, Argentina. It serves as a crucial source rock for vast accumulations of shale oil and shale gas.

In 2010, a major oil discovery was announced by the then-operator Repsol-YPF. Proven reserves are approximated at , with YPF reporting production close to in 2014. By 2012, Repsol YPF had increased its reserve estimates to . The US Energy Information Administration (EIA) assesses recoverable quantities at of oil and of natural gas, exceeding even those found in the Middle Jurassic Los Molles Formation within the Neuquén Basin.

By 2017, hydraulic fracturing operations had expanded to nearly 500 wells in Vaca Muerta, ranking it among the most intensively fracked regions outside North America; this figure surpassed 1500 wells by October 2024.

Concerns regarding environmental impact and social issues have arisen, including protests focused on excessive water consumption and sand mining affecting local agriculture. In 2018, the Mapuche community initiated legal actions against Exxon, TotalEnergies, and Pan American Energy over alleged improper disposal of waste near Añelo, highlighting contamination from hazardous oily sludge linked to fracking activities.

Aside from its energy importance, the formation is recognized for yielding marine reptile fossils.

Geography

The Vaca Muerta Formation—meaning Dead Cow in Spanish—is a Late Jurassic to Early Cretaceous geological unit located within Argentina's Neuquén Basin in northern Patagonia. Since oil extraction commenced in 2011, waste deposits have been reported near Añelo, situated roughly 1,200 km west of Buenos Aires.

Geology

The Vaca Muerta Shale constitutes a continuous reservoir of tight oil and shale gas from the Late Jurassic (Tithonian) through Early Cretaceous (Berriasian), spanning approximately . Positioned at an average depth of , it produces both oil and natural gas. Its composition predominantly includes marl with mature black shales and lime mudstones, exhibiting total organic carbon content between 1% and 5%. Deposited in a marine environment characterized by brittle rocks, this formation generally exceeds in thickness and extends basin-wide. During its formation period, it occupied the eastern margin of the Pacific Ocean.

The term "Vaca Muerta" was coined in 1931 by geologist Charles E. Weaver; however, bituminous shales from southern Mendoza had been described as early as 1892. The formation has also delivered notable paleontological discoveries such as crocodylomorphs and pterosaurs.

Vaca Muerta represents the distal facies within the Lower Mendoza Mesosequence—a sedimentary cycle spanning Tithonian to Valanginian stages. In the southern Neuquén Basin, it grades south-southeastward into carbonate-siliciclastic nearshore units like Carrin Cura and Picún Leufú formations, as well as continental Bajada Colorada deposits. Within the central basin area (Neuquén embayment), it transitions eastward into shoreface Quintuco and sabkha Loma Montosa formations, creating a mixed carbonate-siliciclastic depositional system. Towards the west, it includes slope facies represented by the Huncal Member and extends into shallow marine and volcanic deposits found in Chile.

In southern Mendoza, the Lower Mendoza Mesosequence comprises aggradational sequences up to thick centered within the basin. This includes basinal to middle carbonate ramp deposits of Vaca Muerta alongside middle to inner ramp oyster-bearing Chachao Formation units that form a homoclinal carbonate ramp system. To the west, tidal to continental mixed deposits correlated with both Vaca Muerta and Chachao are designated as the Lindero de Piedra Formation.

Plesiosaurs

Plesiosaurs identified in the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Remarks	Images
Liopleurodon	L. sp.				A pliosaurid belonging to the thalassophonea clade
Pliosaurus	P. patagonicus				A sizeable pliosaurid within the thalassophonea group
Pliosaurus	P. almanzaensis				A sizeable pliosaurid within the thalassophonea group

Ichthyosaurs

Ichthyosaurs from the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Remarks	Images
Arthropterygius	A. thalassonotus				An ichthyosaur classified as an Ophthalmosauridae member
Catutosaurus	C. gaspariniae				An ophthalmosaurid ichthyosaur species
Caypullisaurus	C. bonapartei				A platypterygiine within the Ophthalmosauridae
Ophthalmosaurus	O. sp.				Ichthyosaur of the Ophthalmosauridae family
Sumpalla	S. argentina				A platypterygiine ophthalmosaurid ichthyosaur

Pseudosuchians

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Pterosaurs

Pseudosuchians discovered in the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Remarks	Images
Cricosaurus	C. araucanensis				A metriorhynchine metriorhynchid species
Dakosaurus	D. andiniensis				A geosaurine metriorhynchine metriorhynchid
Geosaurus	G. araucanensis				Geosaurine member of the Metriorhynchidae family
Purranisaurus	P. potens				Geosaurine metriorhynchid species

Pterosaurs recorded from the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Remarks	Images
Herbstosaurus	H. pigmaeus			Partial skeleton	A pterodactyloid pterosaur
Wenupteryx	W. uzi			Partial skeleton of a subadult, including an incomplete ulna	Pterodactyloid pterosaur related to Archaeopterodactyloidea
Pterodactyloidea	Indeterminate			Tibiotarsus	Wingspan estimated to exceed 3 meters; differs from named taxa based on size.

Turtles

Turtles documented in the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Remarks	Images
Neusticemys	N. neuquina				A sea turtle classified as a thalassochelydian
Notoemys	N. laticentralis				A turtle belonging to the Platychelyidae family

Fish

Fish species from the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Notes	Images
Bunoderma	B. baini				A ray-finned fish species
Catutoichthys	C. olsacheri				A member of the caturid group within amiiform fishes
Jonoichthys	J. challwa				Belongs to the aspidorhynchid family of fishes
Leedsichthys	'L. problematicus'				Classified as a pachycormid fish
Leptolepis	'L. australis'				A fish from the leptolepid family
Leptolepis	'L. dubius'				A fish from the leptolepid family
'Notodectes'	'N. argentinus'				A fish belonging to the pachycormiform order
'Pholidophorus'	'P. argentinus'				Part of the pholidophorid family of fishes

Cephalopods

Cephalopods documented in the Vaca Muerta Formation
Genus	Species	Location	Member	Material	Notes	Images
Argentiniceras	A. noduliferum
Aspidoceras	A. euomphalum
Blanfordiceras	B. cf. wallichi
Catutosphinctes	C. sp. A
	C. guenenakenensis
	C. cf. proximus
	C. rafaeli
Corongoceras	C. alternans
Corongoceras	C. mendozanum
Cieneguiticeras	C. perlaevi
Himalayites	H. cf. andinus
Indansites	I. picunleufuense
Karakaschiceras	K. attenuatus
Lissonia	L. riveroi
Mazatepites	M. arredondense
Olcostephanus	O. atherstoni
Physodoceras	P. sp. A
Pseudhimalayites	P. subpretiosus
Pseudolissoceras	P. zitteli
Windhauseniceras	W. internispinosum

Timeline of Oil and Gas Exploration and Production

The Vaca Muerta Shale, serving as a principal petroleum source rock within the Neuquén Basin, supports several oil fields with extraction activities dating back to 1918. Key fields tapping directly into Vaca Muerta include Loma La Lata, Loma Lata Norte, and Loma Campana, mostly managed by YPF. Since operations commenced in 2011, these sites have played a vital role in Argentina's oil production, currently yielding approximately 45,000 barrels per day, highlighting Vaca Muerta's importance in regional energy supply and investment potential.

2008-2013

Confronted with a downturn in gas output and reduced profitability from traditional exploration methods, Repsol-YPF executive Tomas Garcia Blanco launched an initiative in 2008 to explore unconventional shale gas. He assembled a dedicated exploration unit led by Mikel Erquiaga, with German Bottessi concentrating on gas prospects and later M di Benedetto focusing on oil potential. The project received allocated funding and resources, alongside the appointment of Welsh engineer R Ll Lolley as a consultant.

The group pinpointed Vaca Muerta as the foremost target area due to its logistical benefits and significant resource potential. They selected wells across exploration blocks with a systematic approach to testing hydraulically stimulated wells. By March 2012, data had been collected from more than 25 stimulated wells, and investigations into the D-129 source rock yielded encouraging outcomes.

Development logistics necessitated importing drilling rigs and fracturing machinery, while also exploring opportunities for local production of proppant sand. A major obstacle was the scarcity of heavy motor mechanics.

In July 2010, Repsol-YPF successfully drilled Argentina’s inaugural shale gas well at Loma La Lata, followed by a tight oil well at Loma Campana in November. The company achieved its first horizontal well in August 2011. By October 2012, 31 wells had been drilled and completed, expanding Vaca Muerta’s productive area to at least 300 square kilometers.

By 2011, proven reserves were estimated at approximately 927 million barrels; YPF’s production neared 45,000 barrels per day by 2014. In February 2012, Repsol YPF revised its oil reserve estimates upward to 22.5 billion barrels. According to the US Energy Information Administration (2013), recoverable hydrocarbons in Vaca Muerta included 16.2 billion barrels of oil and 308 trillion cubic feet of natural gas.

Price controls on natural gas in Argentina restricted development incentives by capping prices between US$2 and US$2.50 per million BTU; however, tight gas was exempt, enabling Vaca Muerta gas prices to range from US$4 to US$7 in 2011. This pricing environment attracted major players such as ExxonMobil, Total, and Chevron.

In May 2013, YPF entered into a joint venture with Chevron involving a US$1.5 billion investment to drill 132 wells at Loma Campana. Chevron’s participation encountered legal challenges linked to prior rulings concerning Texaco’s operations in Ecuador. In September of the same year, Dow Argentina agreed to invest US$120 million alongside YPF’s US$68 million for drilling 16 natural gas wells within Vaca Muerta’s El Orejano block.

Shell Argentina announced plans to increase its shale capital expenditure nearly threefold to roughly US$500 million in 2014 from US$170 million in 2013. Luis Sapag of the influential Neuquén Sapag family forecasted that a successful YPF-Chevron pilot by March 2014 could lead to investments totaling US$16 billion and generate close to US$9 billion in royalties for Neuquén province.

Developments in 2014

In February 2014, Archer Ltd. secured a contract valued at approximately US$400 million with YPF to supply five new drilling rigs aimed at advancing unconventional shale resource development in Neuquén, Argentina. Later that month, YPF signed a memorandum of understanding with Petronas regarding potential investment opportunities within the Amarga Chica area of the Vaca Muerta formation, spanning 187 km². At this point, YPF’s output from Vaca Muerta exceeded 20,000 barrels of oil equivalent per day from over 150 hydraulically fractured wells operated using 19 rigs.

In March 2014, Helmerich & Payne announced agreements to deploy ten drill rigs from the United States to Argentina under five-year contracts supporting Vaca Muerta activities, complementing its existing fleet of nine rigs already operating locally. In April, YPF CEO Miguel Gallucio confirmed Chevron’s ongoing partnership in the large-scale development of Vaca Muerta. Following a US$1.24 billion pilot project that completed 161 fractured wells across a 20 km² area, Chevron and YPF planned an additional phase involving hydraulic fracturing of another 170 wells with combined investments exceeding US$1.6 billion. The long-term goal was development over an area of 395 km² encompassing more than 1,500 fractured wells producing over 50,000 barrels of oil and three million cubic meters of natural gas daily. Additionally, Chevron committed US$140 million toward a four-year exploration program drilling seven vertical and two horizontal wells in the Narambuena sector under YPF’s operation.

By September 2014, production at YPF’s Loma Campana field had reached 31,000 barrels of oil equivalent per day. In October, Argentine Industry Minister Débora Georgi revealed that YPF had signed a confidential preliminary agreement with Gazprom for a prospective investment valued at around US$1 billion targeting gas exploration and production within Argentina.

2015-present

In January 2015, YPF and Sinopec entered into a memorandum of understanding to collaborate on both conventional and unconventional petroleum development projects. Sinopec Argentina Exploration and Production S.A. was carrying out due diligence alongside YPF for exploration and development activities within sections of Vaca Muerta. During that same month, YPF announced that it, together with Chevron, had invested upwards of US$3 billion in the Loma Campana project, which is regarded as the most important unconventional oil initiative outside the United States.

By April 2015, Loma Campana’s production had reached approximately 44,000 to 45,000 barrels of oil equivalent per day. YPF also formalized a cooperation agreement with Gazprom, despite previous denials about such collaboration. By May 2015, more than 30 oil and gas companies were actively operating in the Vaca Muerta region.

In June 2015, YPF revealed a new gas find at the La Ribera I block, with initial production surpassing 1.5 million cubic feet daily. By November of that year, output from Vaca Muerta climbed to 54,000 barrels of oil equivalent per day, with Loma Campana accounting for 47,000 barrels; Chevron’s investment over two years totaled US$2.5 billion. In the third quarter of 2016, production reached 58,200 barrels per day from 522 wells supported by 11 drilling rigs.

Following the governmental transition in Argentina in September 2016, YPF indicated that revised gas tariffs would facilitate continued development at Vaca Muerta. By 2017, nearly 500 hydraulic fracturing wells were operational there, ranking it among the most intensively fracked sites outside North America.

As of October 2024, over 1,500 fracking wells have placed considerable strain on local infrastructure. The rapid increase in oil production resulted in an energy trade surplus for Argentina for the first time since production commenced in 2012. Plans include a $1.2 billion investment to enhance output at the Rincón de Aranda field. Nonetheless, gas exports remain constrained due to the lack of LNG facilities and pipeline infrastructure.

Blocks and financing

By 2013, Vaca Muerta was segmented into development blocks managed by prominent consortiums. The General Enrique Mosconi concession—including Loma La Lata Norte and Loma Campana fields—is jointly operated by YPF (50%) and Chevron (50%). Petrobras (55%, operator) and Total (45%) oversee development at the Rincon de Aranda concession. The Los Toldos blocks are under the operation of Americas Petrogas (45%), ExxonMobil (45%), and Gas y Petroleo del Neuquén (10%). Águila Mora and Sierras Blancas are developed by Shell (65%, operator), Medanito (25%), and Gas y Petroleo del Neuquén (10%). Wintershall (50%, operator) partners with Gas y Petroleo del Neuquén (50%) at Aguada Federal.

Apache Corporation remained active until divesting its Argentine assets to YPF for US$800 million in 2014. The Bandurria block—previously a joint venture between Pan American Energy, YPF, and Wintershall—was divided into three segments: Wintershall operates Bandurria Norte; Pan American Energy manages Bandurria Centro; and YPF controls Bandurria Sur. In 2015, YPF announced plans to drill 20 wells at Bandurria Sur backed by a US$282.2 million investment aimed at initiating shale oil production within a three-year timeframe.

ExxonMobil holds an 85% stake and operates Bajo del Choique and La Invernada blocks; discoveries were confirmed in both areas during 2014. In 2014, YPF partnered with Petronas to form a joint venture for the Amarga Chica block; Petronas committed US$475 million as part of a US$550 million pilot project. By 2016, an additional US$192.5 million was pledged for expanded drilling operations and infrastructure enhancements.

Since 2013, YPF and Dow Argentina have developed the El Orejano block, which by December 2015 was producing approximately 750,000 cubic meters of shale gas daily from 19 wells. Dow and YPF planned a further US$500 million investment in 2016 to triple production through drilling an additional 30 wells. In January 2016, American Energy Partners and YPF agreed on an investment exceeding US$500 million over three years focused on Bajada de Añelo and Cerro Arena blocks; Pluspetrol and Gas y Petróleo del Neuquén are also involved. Exploration and production efforts include participation from Madalena Ventures, Azabache, and Tecpetrol.

By April 2022, funding for Vaca Muerta projects originated from financial institutions including Citi Bank, Credit Suisse, Deutsche Bank, Goldman Sachs, HSBC, ING, ICBC, and Morgan Stanley. Major urban planning initiatives in Añelo city have received financing support from the Inter-American Development Bank (IDB) and World Bank.

Human rights concerns and ecological consequences

In July 2013, law enforcement authorities forcefully suppressed demonstrations opposing the approval of the US$16 billion YPF-Chevron deal to develop the Loma Campana concession. The extraction process for each oil well demands approximately 640 water deliveries throughout its operational life, which is comparable to the volume of nine Olympic-sized swimming pools. Environmental issues also arise from disputes between sand mining operations and agricultural activities in Dolavon, located in Chubut province.

In 2018, the Mapuche community filed lawsuits against Exxon, TotalEnergies, and Pan American Energy, accusing them of generating "hazardous waste" due to the improper handling of oily sludge produced by hydraulic fracturing near Añelo.

External links

Vaca Muerta entry in the Encyclopedia of Science and Technology in Argentina