**4. Effect of hydrofracking in the USA and worldwide oil and gas proven reserve**

The rapid rise of combined horizontal drilling and high-volume hydraulic fracturing has opened up large, previously unavailable natural gas and oil resources within the lower 48 states of the USA. The opening-up of unconventional "tight gas" formations to exploration and production has greatly increased estimates of technically recoverable US shale gas reserves. Geologists at the US Geological Survey, US Energy Information Administration, as well as in academic settings and energy producers have known the vast natural gas resource locked within the tight shale formations. It is only with the development of horizontal drilling and the perfection of hydrofracking that portions of this resource have been converted to proven reserves, that is, portions of the resource that are able to be economically extracted. **Figure 1** shows the increase in shale gas as a percentage of all natural gas produced in the USA between 2000 and 2015 and indicates the dramatic rise from less than 3% of US natural gas production in 2003 to over 65% of US natural gas production in 2015.

The technological revolution that has increased US natural gas production in the USA has spilled over into and dramatically increased US oil production as well. Oil exploration and extraction are a mature industry in the USA, having begun in the 1860s. US oil production, as well as US proven reserves, had been in a long-term steady decline since 1970. That decline was reversed in 2008, and since 2014 more than half of the oil production in the USA comes from hydrofracked wells. In fact US oil production increased from under 5 million barrels per day in 2008 to over 9 million barrels per day in 2015, and the US Energy Information Administration projects that US oil production will reach 10 million barrels per day by 2018 [3].

**Figure 1.** Natural gas production in the USA in billion cubic feet per day (2000–2015) [5]. Conventional gas shown in dark shading and shale gas shown in light shading.

Countries with the highest technically recoverable tight shale oil and shale gas, as shown in **Table 1**, are found on every inhabited continent. The US Geological Survey has estimated that the technically recoverable shale gas represents a 47% increase in the world's total technically recoverable natural gas and that the technically recoverable shale oil represents an 11% increase [4]. The capital and know-how intensive hydrofracking revolution has only begun in

Effect of Hydrofracking on Aquifers http://dx.doi.org/10.5772/intechopen.72327 37

In terms of aquifers, hydrofracking presents two threats: it uses too much water, and the water it uses becomes polluted and unfit for any other use. This section will address the threat hydrofracking poses to water resources due to imposing a new demand on already stretched water resources. Hydraulic fracturing as a technology is well known as a water hog. The volume of water used per well depends on the length of the horizontal borehole and the formation, but it is not unheard of for a single well to use 20 million liters. This is a consumptive use of water, in that once the hydrofracking chemicals are added and the water is injected into the subsurface, it cannot be reused. For perspective, consider that 20 million liters of sufficient water to meet the basic needs and few health concerns arise for approximately 200,000–400,000 people, according to the World Health Organization [7]. And, that is just the water used for a

As with the most water resource problems, the geographic distribution of available water resource and water need may not align. A look at the hydrofracking experience in the USA is illustrative. Some shale gas formations underlie areas of abundant water, such as the Marcellus shale and Utica shale in the Northeastern USA. This area is well supplied with rivers, lakes, and abundant groundwater. The area is humid and receives on the order of 100 cm of precipitation annually. In contrast the Uinta-Piceance Province in Colorado, located in the Western USA,

a handful of countries, most notably China, Argentina, Mexico, and Algeria.

**Table 1**. Top 10 countries with technically recoverable shale oil and shale gas resources [6].

**quantity and water resources**

single well!

**5. Aquifers and water resources: hydrofracking's threat to water** 

**Figure 2.** Basins with assessed shale oil and shale gas formations [6].

The technological revolution that has transformed the oil and gas proven reserve and production story in the USA is beginning to affect production worldwide. The US Energy Information Administration has found that tight shale gas and tight shale oil resources are distributed around the world (**Figure 2**).

#### Effect of Hydrofracking on Aquifers http://dx.doi.org/10.5772/intechopen.72327 37


**Table 1**. Top 10 countries with technically recoverable shale oil and shale gas resources [6].

Countries with the highest technically recoverable tight shale oil and shale gas, as shown in **Table 1**, are found on every inhabited continent. The US Geological Survey has estimated that the technically recoverable shale gas represents a 47% increase in the world's total technically recoverable natural gas and that the technically recoverable shale oil represents an 11% increase [4]. The capital and know-how intensive hydrofracking revolution has only begun in a handful of countries, most notably China, Argentina, Mexico, and Algeria.
