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  2. Types

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- [Voiceover] If we look at the different types of geothermal resources that we around the world, the most obvious one are the volcanic geothermal systems for example, Los Azufres in Mexico and practically all the geothermal systems that are in exploitation in Central America and part of the United States too, we have other geothermal systems that are less evident in the sense that they don't have an evident volcano related to them. In the basin and range programs in in the United States we have many hot springs which thermal energy is probably coming from distribution of fluid through the deep folds that pick up the heat and they are discharged at the surface, we also geopressurized systems that are related are related to these geopressurized sedimentary basins especially here in the United States and finally the enhanced geothermal systems that can be divided into Conduction-dominated Systems, sedimentary basins, sedimentary systems and basement systems. So let's look at the characteristics at least of the systems that are of interest for us for the oil industry, which is the geopressurized systems and the hydrothermal systems. The geopressurized systems are reservoirs that are deep in the earth between four and five kilometers and large sedimentary basins that contain water. This water has remain trapped at the time of deposition have been subjected to very high temperatures and pressures. Pressures can be in the range of 1000 to 4000 psi, temperature can be between 250 and 400 Fahrenheit degrees, and they're characterized by a very high salinity that can be on the order of 85% sodium chloride. In addition they can contain a relatively high concentration to gases and the depths at which we find them is up to on the order of 10 thousand feet. Obviously because of the charaacteristics of theses systems we have many potential uses for the fluid, one of them is obviously the thermal energy production with the pressurized hot water but also we can get hydraulic energy and we can also extract the gases. In the case of the United States one interesting thing is that we have many systems that conform to those characteristics, as you can see in this map of the United States with all the different geopressurized basins that we have already available. These basins that we are going to see later have already in many cases been exploited for oil and gas production, too, so in many of these basins we already have a well that has been drilled and that have been used for ensuing production. So in terms of the enhanced geothermal systems the conduction-dominated systems were initially called hot dry rock and these were systems where we have a great amount of heat, the temperature was good, hot, we didn't have wells that needed anything, for example systems are hotter in granite, the way that these systems have been exploited in the past is to crack the rocks using cold water, we have a well here that injects the cold water, thermal shock together with the pressure makes the rocks to fracture and then you can see that in these fractures you can transport the fluid and then pick up the heat that is later extracted through a production well, this is the way that originally geothermal systems were exploited and that's the worry in this comes precisely from the fact that you have to produce these additional fractures. On the other hand we also have sedimentary and basement type systems these are, the difference between them and the conductive-dominated systems is only the type of rock. In the case of the sedimentary and basement types we still relatively low permeability that doesn't allow us to extract the fluid easily We need to apply also the fractures to be able to recover the fluid. Heat is transferred to the injected water obviously and in this way we can extract the fluid to generate electrical energy.