Geological Structures Within The Earth

Hydraulic fracturing is also known as “fracking” is a technique which involves drilling down, then horizontally as far as 10,000 feet below the surface to release natural gasses stored in the sedimentary rock known as Shale. The channel is then encased with concrete or occasionally steel to allow millions of gallons of water to be injected into the wellbore. Most water used in fracking comes from surface water sources such as rivers, lakes, or other accessible bodies of water nearby. Not only is there water being funneled into the wellbore, but also a mixture of sand and other chemicals. When the high-pressure mixture is injected underground it fractures the Shale around the wellbore and creates fissures. The fissures are then held open with

The extraction of natural gas requires a borehole which is dug down to the deep shale formation. After the hole is dug, a steel pipe is inserted into the borehole where it is encased with cement on the outer perimeter of the pipe. A perforation gun is lowered into the cement-encased piping. Using an explosive, the perforation gun perforates the casing and puts initial fractures into the shale at targeted locations. The shale is fractured further by inserting fracking fluids, which consists of 98% water and sand, plus 2% proprietary fluids. The fracking fluids are pushed down into the wellbore and pressurized to 3000 psi causing the initial fracture to spread in the shale, along the shale natural fracture lines. The sand in the fracking fluids keeps the created fractures open which allows the gas from the shale pores to flow into the casing and then to the surface, where it is collected.

Generally, shale is a fine-grained sedimentary rock created from silt and clay-size mineral particles with properties to substance we commonly call “mud”. In geological term, shale is categorized as one of the mudstones. Properties of shale is rather distinguishing as it is made up of many thin layers which readily splits into thin pieces of layers. Shale can be used for numerous application based on the substance which exist in the shale formation. Most shale can be crushed and mixed with water to create clays for molding into object or bricks for houses. Some shale can even create cement by combining with limestone. For this paper, we only focus on one specific shale category which is oil shale.

The water supply on earth plays a huge role in daily lives. You need to have clean water to drink, do laundry and water your garden. Since water is necessary, the future water supply is very important for future generations. They will need clean water to use daily. Society can not let the water become so polluted and unsanitary that future generations can not use it for their daily needs. Water supply is affected by humans and the area surrounding the water.

Based off of MICP data collected from core (Figure 19), the Pronghorn siltstone has a permeability on par with the upper and lower Bakken shales. The lack of permeability is supported by lithological analysis indicating a clay content of up to 50 % (Figure 20) across the Painted Woods asset. The low permeability and high clay content shows that the Pronghorn does have the potential to occlude primary migration of hydrocarbons from the lower Bakken shale into the underlying upper Three Forks. However, this only has a minimal effect on the overall potential of the upper Three Forks as a whole.

According to an article in The New York Times, hydraulic fracturing is best described as the technique used to drill down into the earth using a high pressure water mixture to fracture the rocks and extract the natural gas and oil. Approximately one million wells have been fracked since the 1940’s, most of these are vertical wells that drill into porous sandstone or limestone. New technology has allowed for horizontal drilling to capture gas from shale rock. Water, sand and other chemicals are injected into the rock at a high pressure to create the fractures that release the gas. The chemicals added to the water dissolve minerals, kill bacteria that may plug up the well and

To those in the energy industry, it refers purely to the process of injecting fluids-which consist of water and between three and twelve chemicals, including hydrochloric acid, sodium chloride, methanol, and isopropyic ethanol, that serve various functions-underground at high pressure to crack open shale rock, release natural gas or oil trapped there, and allow the hydrocarbons to flow to the surface. (24)

and relationships of a working model. If a testable hypothesis is confirmed by a large

The process of the collection of an underground fluid would not be possible without the use of hydraulic fracturing. In the Shale reserves, located about 5,000 feet underground, suffer an extremely low permeability rate. Permeability is the measure of how well a fluid flows through an absorbent material at the depth, and within such nonporous rock, the ability of fluids to travel to the well is greatly limited. Fracturing increases the area of the fluid that is exposed to porous materials and thus greatly increases production. The method of fracturing utilizes a few key components which allow for an economical extraction of resources.

Fissures created by high pressure fracking fluid to increase gas flow to the well also create pathways for leakage and consequent contamination of groundwater (Yu et al. 2014). Boreholes drilled for well access must pass through shallower strata, which may contain groundwater aquifers, before reaching target natural gas reservoirs (Davies et al. 2014). Passing through shallow layers of strata introduces a potential source of contamination to groundwater resources (Davies et al. 2014). Leakage into groundwater wells can occur due to poor well completion practices, the corrosion of steel casing, and the deterioration of cement during production of shale gas (Davies et al. 2014). Therefore, shale gas well integrity is important in reducing contamination events.

One of the most highly debated topics in the gas industry is hydraulic fracking. News about it is on the radio, tv and all over the internet. The truth about hydraulic fracking can be hard to find but is imperative to know the truth. The U.S Energy Information Administration estimates that the United States has 2,119 trillion cubic feet of recoverable gas. They predict that 60% of this gas is “unconventional gas” that is stored in low permeability formations such as shale, coalbeds, and tight sands (Jackson, 2011).

Hydraulic fracturing or “fracking” is a process that fractures rock formations in the earth’s surface in order to release hydrocarbons. When these hydrocarbons are released, they flow more freely through the rocks and up to the wellbore, were oil and gas are extracted to (Suchy, 2012). Not all rock formations require a hydraulic fracturing operation to be done because the fluids move freely through rocks that have been naturally fractured. Shale gas reservoirs on the other hand are not permeable and have very few natural fractures; therefore the trapped gas and oil must be extracted by fracking only.

Gas and oil is usually formed over thousands and thousands of years under large bodies of water, where organic materials have died. The organic material of plants and animals settle to the bottom of the waters floor and

Besides the ideal physical structure for oil and gas reservoirs formed in the Gulf of Mexico, the nature also prepared all of other necessary conditions to form and accumulate oil and gas, such as organic source, pressure and temperature. According to the chemical and biological description, Oil is basically a mix of naturally occurring organic compounds from within the earth that contain primarily hydrogen, carbon and oxygen. Dead animals, algae and bacteria, which are considered as the fundamental source to form oil and gas, were absolutely abundant at the early Jurassic era, when the Gulf of Mexico basin was just well formed. After the death of living creatures such as animal and plants, most of their bodies are destroyed by bacteria. Some of these organic material settled down to the bottom of the seafloor, where there was no oxygen at all, being protected from the bacterial actions. Through certain chemical reaction, the leftover organic material mixed with sediments turned into a substance named Kerogen .

Shale is the most common sedimentary rock. It was deposited and formed by squeezing excess formation water and mineralogical transformations at different temperatures and pressures. Caprocks are essentially defined as low permeability formations, and sometimes, but not necessarily, with low porosity. More than 60% of effective seals for geologic hydrocarbon bearing formations as natural hydraulic barriers constitute of shale rocks. Shale rocks are predominantly composed of clay such as kaolinite, montmorillonite and illite. They might also have other silica and carbonate based minerals that contribute to their geomechanical strength. In 1965, D. Shaw and C. Weaver documented the average mineralogical composition of shale from three hundred