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Shale Gas - Fracking - Vaca Muerta
Have you ever heard of shale gas? It is methane gas, trapped in the microporosity of clay rocks, found in unconventional reservoirs. In this new video we will explain what it is, where it is found, and how it is extracted.
Shale Gas is the term used to specify this particular type of reservoir, that lies at a greater depth than conventional reservoirs. Beyond the aquifers, the limestone and sandstone rock layers, between 2,000 and 4,000 meters deep, we find segments of shale, a sedimentary rock mainly composed of mud and clay minerals; this rock, once decomposed anaerobically, can give rise to the Gas deposits. The nation with the largest shale gas reservoir is China, followed by the United States. Large-scale exploitation of shale gas began in the 2000s when the price of hydrocarbons was rising sharply. The U.S. pioneered new extraction techniques for unconventional wells: from 2000 to 2010, production increased from 10 to 140 billion cubic meters, about 23% of the country’s energy requirements, while in the decade from 2010 to 2020, production exceeded domestic natural gas needs, to such an extent that the U.S. went from being an importer to an exporter of methane gas.
The clay contained in Shale Gas rock makes the reservoir quite impermeable, and to extract methane gas from these particular sources a complex technique called FRACKING must be adopted. This technique was developed in 1860 in Pennsylvania, when efforts were made to increase the productivity of oil wells by fracturing the well’s compact rocks with Nitroglycerin; the technique was improved later in 1947, by the Stanolind Oil and Gas Corporation, using a high-pressure liquid to fracture the rock.
Let’s see how this technique works.
When geophysical analysis detect a new reservoir, first thing they need to set up the site. In every site there is a drill head, a series of high-pressure pumps, seismic monitoring instruments, piping and pressure gauges to regulate the flow; firstly the workers have to drill the soil vertically in order to reach the depth of the reservoir, secondly they drill it horizontally to cross the width of the site. If the rock layer is very compact, explosive is descended into the well to create microcracks. Otherwise, in case microcraks are already there, a high-pressure fluid is injected to expand the cracks and make the rock more permeable; the injected fluid can be water, foam, gel or compressed gas such as nitrogen.
The liquid is mixed with some solid material, called Proppant, such as resin, sand or ceramic spheres which are intended to keep the fractures open when the water pressure is gone. Sometimes natural radioactive tracers are added to the fracturing liquid to follow the progress of the fractures. This whole process is monitored from the surface by Geophones that are placed throughout the area and detect seismic movements. Pumps extract the liquid from the well, taking out the methane gas that has been released from the rock pressure; at the surface the gas get separated from the liquid and stored in tanks which are kept under pressure; the liquid with the excavated waste is discharged into a tank, which filters it with the aim or reusing it.
Have you ever heard of shale gas? It is methane gas, trapped in the microporosity of clay rocks, found in unconventional reservoirs. In this new video we will explain what it is, where it is found, and how it is extracted.
Shale Gas is the term used to specify this particular type of reservoir, that lies at a greater depth than conventional reservoirs. Beyond the aquifers, the limestone and sandstone rock layers, between 2,000 and 4,000 meters deep, we find segments of shale, a sedimentary rock mainly composed of mud and clay minerals; this rock, once decomposed anaerobically, can give rise to the Gas deposits. The nation with the largest shale gas reservoir is China, followed by the United States. Large-scale exploitation of shale gas began in the 2000s when the price of hydrocarbons was rising sharply. The U.S. pioneered new extraction techniques for unconventional wells: from 2000 to 2010, production increased from 10 to 140 billion cubic meters, about 23% of the country’s energy requirements, while in the decade from 2010 to 2020, production exceeded domestic natural gas needs, to such an extent that the U.S. went from being an importer to an exporter of methane gas.
The clay contained in Shale Gas rock makes the reservoir quite impermeable, and to extract methane gas from these particular sources a complex technique called FRACKING must be adopted. This technique was developed in 1860 in Pennsylvania, when efforts were made to increase the productivity of oil wells by fracturing the well’s compact rocks with Nitroglycerin; the technique was improved later in 1947, by the Stanolind Oil and Gas Corporation, using a high-pressure liquid to fracture the rock.
Let’s see how this technique works.
When geophysical analysis detect a new reservoir, first thing they need to set up the site. In every site there is a drill head, a series of high-pressure pumps, seismic monitoring instruments, piping and pressure gauges to regulate the flow; firstly the workers have to drill the soil vertically in order to reach the depth of the reservoir, secondly they drill it horizontally to cross the width of the site. If the rock layer is very compact, explosive is descended into the well to create microcracks. Otherwise, in case microcraks are already there, a high-pressure fluid is injected to expand the cracks and make the rock more permeable; the injected fluid can be water, foam, gel or compressed gas such as nitrogen.
The liquid is mixed with some solid material, called Proppant, such as resin, sand or ceramic spheres which are intended to keep the fractures open when the water pressure is gone. Sometimes natural radioactive tracers are added to the fracturing liquid to follow the progress of the fractures. This whole process is monitored from the surface by Geophones that are placed throughout the area and detect seismic movements. Pumps extract the liquid from the well, taking out the methane gas that has been released from the rock pressure; at the surface the gas get separated from the liquid and stored in tanks which are kept under pressure; the liquid with the excavated waste is discharged into a tank, which filters it with the aim or reusing it.
The production of shale gas has ignited strong debates over the years because of its possible effects on the world climate and global warming. The technique used, unfortunately, releases small amounts of methane gas into the environment at the initial stage; in addition, earlier created micro-fractures could dangerously allow the gas to reach aquifers. The tanks built with the purpose of holding the fracking fluids, if not well constructed, can leak into the ground and get into the aquifers as well, contaminating the wells from which houses get their water.
The consumption of water mixed with chemicals (to reduce friction and the microorganisms’ creation) that is used for fracturing is really huge! Generally just for a single well 9 to 29 thousand cubic meters of water are used, only 50% to 70% of which is recovered, whereas the remaining added water leaks into the surrounding soil, with the possibility of polluting domestic acquifers.
Seismic risk is another worrying consequence of Fracking, that makes use of explosives to reduce pressure in compact rock layers. By the way, certified data supporting this theory have not been developed yet.
Many countries, especially in Europe, have banned shale gas production because of the negative impact it has on the environment; but there is another factor blocking extraction from these reservoirs, which is the large amount of money involved in exploiting these sites. Unlike conventional reservoirs, shale gas needs more extraction wells; this means higher costs that only a few nations can afford. This is the case of Argentina, with its reservoir called Vaca Muerta, named after the rocky conformation adjacent to the site; we are talking about a 36,000-square-kilometer field, 308 trillion cubic feet of natural gas could be extracted, leading Argentina to be the second largest LNG (liquefied natural gas)-producing nation in the world. The development of Vacua Muerta requires an investment of $7 to $8 billion per year, with a project involving a new distribution network that will cross the entire country, bringing power to the center and the north of the nation. Infact, the Argentine government is keen to welcome investors; at this moment in history Vaca Muerta is a reserve that the world desperately needs.
By this video, we took a short journey to discover shale gas, learning about the technique used for extraction, and its environmental complications that still keep many European countries away from exploiting this resource. The global community is becoming increasingly aware of the actions necessary to protect our earth, but with a society still marching down the road of consumerism, when conventional hydrocarbon supplies are finished, will they make the decision to exploit shale gas reservoirs as well? Please write a comment and share your opinion with us.
The consumption of water mixed with chemicals (to reduce friction and the microorganisms’ creation) that is used for fracturing is really huge! Generally just for a single well 9 to 29 thousand cubic meters of water are used, only 50% to 70% of which is recovered, whereas the remaining added water leaks into the surrounding soil, with the possibility of polluting domestic acquifers.
Seismic risk is another worrying consequence of Fracking, that makes use of explosives to reduce pressure in compact rock layers. By the way, certified data supporting this theory have not been developed yet.
Many countries, especially in Europe, have banned shale gas production because of the negative impact it has on the environment; but there is another factor blocking extraction from these reservoirs, which is the large amount of money involved in exploiting these sites. Unlike conventional reservoirs, shale gas needs more extraction wells; this means higher costs that only a few nations can afford. This is the case of Argentina, with its reservoir called Vaca Muerta, named after the rocky conformation adjacent to the site; we are talking about a 36,000-square-kilometer field, 308 trillion cubic feet of natural gas could be extracted, leading Argentina to be the second largest LNG (liquefied natural gas)-producing nation in the world. The development of Vacua Muerta requires an investment of $7 to $8 billion per year, with a project involving a new distribution network that will cross the entire country, bringing power to the center and the north of the nation. Infact, the Argentine government is keen to welcome investors; at this moment in history Vaca Muerta is a reserve that the world desperately needs.
By this video, we took a short journey to discover shale gas, learning about the technique used for extraction, and its environmental complications that still keep many European countries away from exploiting this resource. The global community is becoming increasingly aware of the actions necessary to protect our earth, but with a society still marching down the road of consumerism, when conventional hydrocarbon supplies are finished, will they make the decision to exploit shale gas reservoirs as well? Please write a comment and share your opinion with us.