Vaca Muerta
The Vaca Muerta Formation, commonly known as Vaca Muerta, is a geologic formation of Late Jurassic to Early Cretaceous age, located in the Neuquén Basin in northern Patagonia, Argentina. It is well known as the host rock for major deposits of shale oil and shale gas.
The large oil discovery in the Vaca Muerta Formation was made in 2010 by the former Repsol-YPF. The total proven reserves are around, and as of 2014 YPF's production alone was nearly. In February 2012, Repsol YPF SA raised its estimate of oil reserves to. The US EIA estimates total recoverable hydrocarbons from this Vaca Muerta Formation to be of oil and of natural gas, more than even the Neuquén Basin's hydrocarbon-rich Middle Jurassic Los Molles Formation holds.
As of 2017, there were almost 500 fracking wells, one of the most fracked sites outside North America, and as of October 2024, there were over 1500 fracking wells.
In July 2013, protests were heavily repressed by the police. The huge water consumption of fracking as well as the sand mines interfere with agriculture. In 2018, the Mapuche sued Exxon, French company TotalEnergies and Pan American Energy for "dangerous waste" due to "deficient treatment" close to the town of Añelo as oily sludge residue from fracking was tipped in illegal waste dumps.
The formation is also known for its fossils, such as those of marine reptiles.
Geography
The Vaca Muerta Formation, commonly known as Vaca Muerta, is a geologic formation of Late Jurassic to Early Cretaceous age, located in the Neuquén Basin in northern Patagonia, Argentina.Waste from the oil exploitation since 2011 has been deposited close to the town of Añelo, which is about 1,200km west of Buenos Aires.
Geology
The Vaca Muerta Shale is a continuous tight oil and shale gas reservoir of Late Jurassic and Early Cretaceous age. The formation covers a total area of. The shale is at a depth of about, where it has been found productive of oil and gas. Although called a shale, and with a total organic carbon content varying from 1 percent to 5 percent, the Vaca Muerta is predominately marl and consists of mature black shales, marls and lime mudstones. Formed in a marine environment with little clay and brittle rock, the deposit is thick, extending throughout the basin. At the time of deposition, the Vaca Muerta was situated on the eastern margin of the Pacific Ocean.Although the name Vaca Muerta Formation was introduced to the geological literature in 1931 by American geologist Charles E. Weaver, the highly bituminous shales in the Salado River valley in southern Mendoza were described in 1892 by Dr. Guillermo Bodenbender. German paleontologists Beherendsen and Steuer determined the Tithonian age of these shales. In several outcrop locations, the Vaca Muerta Formation has been the site of paleontological finds: the crocodylomorph Cricosaurus and possibly Geosaurus, the ichthyosaur Caypullisaurus, and the pterosaurs Herbstosaurus and Wenupteryx.
The Vaca Muerta Formation represents the most distal facies of the Lower Mendoza Mesosequence, a Tithonian–Valanginian broad shallowing-upward sedimentary cycle.
In the southern part of the Neuquén Basin the Lower Mendoza Mesosequence includes the basinal deposits of the Vaca Muerta Formation, which to the south-southeast change to mixed carbonate-siliciclastic nearshore deposits of the Carrin Cura Formation and Picún Leufú Formation, and to continental deposits of the Bajada Colorada Formation of Tithonian – Berriasian age.
In the central part of the Neuquén Basin, also known as Neuquén embayment, the Lower Mendoza Mesosequence consists of basinal deposits of the Vaca Muerta Formation, which to the east change to shoreface deposits of the Quintuco Formation, and to sabkha deposits of the Loma Montosa Formation, forming a mixed carbonate-siliciclastic depositional system. Westward the Vaca Muerta Formation includes slope facies, and in the Chilean territory pass into shallow marine/volcanic deposits.
By contrast, in the southern Mendoza area the Lower Mendoza Mesosequence consists of aggradational and divergent sequences, with a maximum thickness of towards the center of the basin. It includes basinal to middle carbonate ramp deposits of the Vaca Muerta Formation and middle to inner ramp oyster-deposits of the Chachao Formation, which form an homoclinal carbonate ramp system. Westward, undated tidal to continental mixed deposits have been recognized and correlated with the Vaca Muerta and Chachao Formations, receiving the name of Lindero de Piedra Formation.
Paleobiota
Vertebrates
Plesiosaurs
Ichthyosaurs
Pseudosuchians
Pterosaurs
Turtles
Fish
Invertebrates
Cephalopods
Oil and gas exploration and production timeline
The Vaca Muerta Shale had long been known as a major petroleum source rock for other formations in the Neuquén Basin, which has had oil production since 1918. Wells producing from the Vaca Muerta itself are in several oil fields, including the Loma La Lata, Loma Lata Norte, and Loma Campana fields.2008-2013
Given the natural decline in gas production and dimininishing returns from conventional exploration activity, in 2008 Repsol-YPF executive Tomas Garcia Blanco sponsored the search for "unconventional" shale gas by:1) Configuring a team of explorationists under the leadership of Mikel Erquiaga with German Bottessi heading the team searching for gas. M di Benedetto was added to the team once the oil potential was fully identified.2) Assigning budget and resources to that team. 3) Appointing a Welshman as engineering advisor.This team screened all Argentine source rock formations and proposed Vaca Muerta as principal objective because logistics were easier and it held greater potential.
Target well locatíons were selected in most of the exploration and production leases. A policy of systematically testing the wells after they had been stimulated was adopted with wells in the Loma La Lata/ Loma Campana area being tied into existing production facilities. By March 2012 data was available from over 25 stimulated wells. The D-129 source rock had also started to be explored had tested positive.
As part of the visualization the logistics required to develop the assets were investigated with the need for importation of drilling rigs and fracturing equipment being identified together with an opportunity for ín-country proppant sand production. The critical path was however the availability of heavy motor mechanics.
In July 2010, Repsol-YPF recognized the productive potential of the Vaca Muerta Shale of the Neuquén Basin, and completed Argentina's first shale gas well at the Loma La Lata field. In November 2010, the company completed a tight oil well in the Vaca Muerta Shale in the Loma Campana area. In August 2011, the first horizontal well in the Vaca Muerta was drilled and completed. By October 2012, 31 wells had been drilled and completed, and another 20 had been drilled and were awaiting completion. The drilling had extended the Vaca Muerta producing extent to an area of at least.
As of 2011, the total proven reserves were around, and as of 2014 YPF's production alone was nearly. In February 2012, Repsol YPF SA raised its estimate of oil reserves to. The US EIA estimated in 2013 total recoverable hydrocarbons from Vaca Muerta Formation to be of oil and of natural gas, more than even the Neuquén Basin's hydrocarbon-rich Middle Jurassic Los Molles Formation holds.
One problem in attracting development was Argentina's price controls on natural gas, keeping the price down to US$2.00-$2.50 per million BTU. However, the government exempted tight gas from controls, and in 2011 the Vaca Muerta gas was selling for US$4–$7. The higher gas prices attracted major oil companies, including ExxonMobil, Total S.A., and Chevron Corporation to Vaca Muerta.
In May 2013, YPF announced that it had negotiated a joint venture in which Chevron Corporation would invest US$1.5 billion drilling 132 wells on the Loma Campana field. Chevron's participation was complicated by efforts by the plaintiffs who obtained a judgement in Ecuador with respect to actions by Texaco in the Lago Agrio oil field to collect the judgement from Chevron's Argentine assets. On September 24, 2013, YPF announced that Dow Chemical Company subsidiary Dow Argentina had signed an agreement to drill 16 natural gas wells in the El Orejano block of the Vaca Muerta formation over a 12-month period, with Dow contributing US$120,000,000 and YPF US$68,000,000. Shell Argentina CEO Juan José Aranguren was quoted on December 10, 2013, as saying his company, with 4 producing wells in Vaca Muerta and 2 more drilling, would triple capital spending in Argentine shale to "about" US$500 million in 2014 from US$170 million in 2013. Luis Sapag, of the Sapag family which has dominated Neuquén politics for half a century, was reported by Bloomberg in December 2013 as saying that the YPF-Chevron joint venture would invest as much as US$16 billion if the US$1.2 billion pilot venture was successful by March 2014, which would generate almost US$9 billion in royalties for Neuquén.
Developments in 2014
In February 2014, Archer Ltd. announced it had an "approximately US$400 million" contract with YPF to provide "five new built drilling rigs to support YPF's development of unconventional shale resources in the Neuquén area in Argentina." On February 18 of the same year, YPF announced that it had signed a memorandum of understanding with Petronas on a possible investment in the 187 square kilometer Amarga Chica zone of the Vaca Muerta formation; YPF also indicated that its current production in Vaca Muerta was over 20,000 barrels of oil equivalent a day from over 150 fracked wells using 19 fracking drill rigs. Helmerich & Payne disclosed on March 5, 2014, that it had contracted with YPF to deploy 10 drill rigs under five-year contracts from the United States to Argentina between the third quarter of 2014 and the first quarter of 2015 to work in the Vaca Muerta play in addition to the nine rigs Helmerich & Payne already had in the country. On April 10, 2014, Miguel Gallucio of YPF announced that Chevron had decided to continue its partnership with YPF in the "massive development" of Vaca Muerta; the US$1.24 billion pilot program financed by Chevron and ended in March had developed 161 fracked wells in a 20 square kilometer area. The new phase would frack 170 additional wells that year with a joint investment of over US$1.6 billion, with YPF continuing as operator. The goal agreed upon for future years would be to develop an area of 395 square kilometers with over 1500 fracked wells producing over 50,000 barrels of oil and 3 million cubic meters of natural gas a day. Chevron and YPF also agreed on a US$140,000,000, four-year exploration project to drill and analyze 7 vertical and 2 horizontal wells in a 200 square kilometer area in the Chihuido de la Sierra Negra concession, to be financed by Chevron with YPF as operator. In an interview with the Argentine newspaper La Nación published September 14, 2014, Gallucio indicated that production in the Loma Campana field had reached 31,000 barrels of oil equivalent a day.On October 8, 2014, Argentine Industry Minister Débora Georgi reported that YPF had signed a confidential agreement in principle with Gazprom that could lead to a US$1 billion investment in gas exploration and production "in Argentina".