Hydrocarbon recovery forms the crux of the oil and gas energy. Ever since petroleum was established as a source of energy, the oil and industry has always persevered to improve and optimize conventional recovery techniques in an effort to boost production and profits. Nevertheless, the increased over- dependency on hydrocarbons has exhausted reserved from the most commercially viable wells/plays, which is to say that wells requiring standard exploration and production techniques are now on a decline. However, oil and gas deposits are very much available in many regions as shown in Figure 1.1. Most of them exist as unconventional resources usually treated as possible reserves.
Figure 1 - Distribution of oil reserves
When dealing with unconventional resources, conventional recovery methods become obsolete. In fact, the costs of recovering unconventional resources are significantly higher than conventional resources due to presence of additional, more sophisticated processes such as hydraulic fracturing and steam assisted gravity drainage. An example of an unconventional resource would be shale rock, which contains shale oil and shale gas. Unlike regular sedimentary rocks, shale rock requires a combination of hydraulic fracturing and horizontal drilling in order to be commercially viable for further marketing purposes. Unsurprisingly, unconventional hydrocarbon recovery poses much more of a challenge than regular techniques and should therefore be considered a resource play rather than an exploration play.
This paper serves to examine the prospect of using a single perforation cluster as opposed to multiple perforation clusters within a single stage. Institutively speaking, the usage of multiple clusters is thought to result in a h...
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...f pathways to promote hydrocarbons flow, by increasing the number of perforation clusters within a single stage of a play, we risk reducing the initial gas rate and overall gas recovery due to a decrease in the width(s) growth of the center and sub center surfaces of the fractures. Based on the analysis of the Marcellus Shale, an optimal number of clusters would be approximately between 1-6. However, given that each formation is unique, it is important to analyze other parameters in order to determine the best/optimal number of clusters for a specific region.
2) However, the problem above can potentially be adjusted by introducing a fair cluster spacing mechanism. Based on the analysis of all four cases, a higher degree of spacing results in a greater recovery factor potentially due to a decrease in the mechanical interaction between rocks (pore systems).
This area is known as the Permian Basin. Most of the oil is being produced from rocks
In today's global economy, energy is one of the most crucial and sought after commodities. Who supplies it and how much they supply determines how much influence they have over other countries as well as the global economy. This is why hydraulic fracturing is currently such an important and controversial topic in the United States. Hydraulic fracturing, more commonly known as "fracking" or hydrofracturing, is the process of using pressurized liquids to fracture rocks and release hydrocarbons such as shale gas, which burns more efficiently than coal. This booming process of energy production provides a much needed economic boost, creating jobs and providing gas energy for Americans. The efficiently burning shale gas reduces carbon emission from electricity production plants, reducing carbon footprints on the environment. However, the process of hydraulic fracturing uses millions of gallons of pressurized liquid, which contains toxic chemicals, and some of this water is left over undealt with. The air near fracking sites is often also polluted and unsafe for nearby community residents. Injecting millions of gallons of water laced with toxic chemicals into the rock thousands of feet deep can cause earthquakes, causing a safety hazards for all nearby areas. Hydraulic Fracturing makes rare natural gases easily attainable, boosting the economy and reducing carbon emissions. However, the negative side effects such as contaminated water and air, make hydraulic fracturing a process that may not be worth the benefits.
Gas in shale formations are“low in permeability,” making it very tedious to extract, but with the increase in technological knowledge in fracking and horizontally drilling into shale beds, the vast reserves of natural gas resource could be extracted (4). Fracking is a large industrial operation that boost the “productivity of a oil or gas well” (5). It is a process by which, under very high pressure, a mixture of water, chemicals, and sand, are pumped into shale formations that causes fractures in the rocks to open wider or create new fractures that would allow otherwise trapped oil and gas to flow into the wells (6).
Two properties are required for fluid movement of Reservoir rocks and Source rocks: permeability and porosity. It consist voids or pores, ability to contain fluid (known as porosity) and the pores are interconnected (permeability) in order to allow flow to occur. Hydrocarbons can be termed as reservoir fluid. The volume of hydrocarbons stored in a reservoir depends upon the porosity of the reservoir rock. The rate and volume at which hydrocarbons are withdrawn depends upon the permeability of the reservoir rock. Almost complete pore space of the superior several kilometres of earth’s crust contains water. Therefore in this water environment hydrocarbons exist with amalgamation of oil, gas and water occurring in different proportions.
...ydraulic fracturing. During Hydraulic fracturing, or fracking, holes are drilled into shale rock formations, deep beneath the earth's surface and injected with more than a million gallons of pressurized fracking fluid. This process creates small fissures within the rock layers that are held open by the sand particles, allowing the natural gas to vacate from the well (10). However, there is much debate over the long-term vitality and validity of the use of unconventional gas as a solution to the United States dependency on foreign oil. Much of this debate stems from what some have coined as the "exploration treadmill", the rate at which new plays must be added to production, in order to maintain a flat line and or growing (carbon)
...luence on migration, aggregation and forming reservoir. There have two aspects. On the one hand, the development of cracks in the shale can greatly improve the permeability of the reservoir; it also can increase the aggregate amount of free gas; and it can promote the migration of shale gas as a drainage system.
America is facing an energy revolution. The shift from traditional energy sources such as coal and oil are fading while newer sources are being used to sustain an insatiable thirst for energy. A front-runner is natural gas, a cleanly burning and abundant alternative for conventional energy sources. This nonrenewable resource is found miles underground in prehistoric shale deposits, to show the magnitude “North America has approximately 4.2 quadrillion (4,244 trillion) cubic feet of recoverable natural gas that would supply 175 years worth of natural gas at current consumption rates” locked in these shale deposits (Loris). However, the dilemma comes from how natural gas is extracted from the earth. One of the processes of accessing the natural gas is called Hydraulic Fracturing or “Fracking”. It is the process of shooting a highly pressurized mixture of water, sand, and chemicals into cracks in the shale deposits, essentially fracturing the shale that then releases the natural gas (Malakoff).
Rao, Vikram. Shale Gas: The Promise and the Peril. Research Triangle Park, NC: RTI, 2012. Print.
Fracking is a procedure that uses high-pressure fluids to obtain shale gas through the drilling of underground rocks. According to Broderick et all (2011), shale gas1 is found trapped within the shale2 formations, it is a very flexible substance as it has a wide range of uses, such as automobile fuels, domestic use and power generation. Nowadays, the gas demand is increasing vastly. Shale gas is one of the main sources of energy for some countries, such as United States of America and United Kingdom (Broderick et al. 2011). The low permeability3 of the shale makes difficult the flow of the gas inside it, therefore, it makes inviable to extract the substance without the support of hydraulic fracturing. Higher the permeability of a rock, higher the flowing of the fluid on it (King 2012). In order to improve the shale gas extraction, a high pressure mixture of water, sand and other additives is injected in the rock to increase its fractures and facilitates the flowing of the gas and its capture (Howarth et al. 2011). The figure below illustrates the fracking process.
Tissot, B.P, and D.H Welte. Petroleum Formation and Occurance: A New Approach to Oil and Gas Exploration. N.p.: Springer, 1978. Print.
The extraction of crude oil from the Athabasca oil sands is carried out by surface mining and in situ mining. 90% of recoverable bitumen is located too deep to be recovered by surface mining (Mossop, 1980). Both techniques require invasive processes to successfully extract the bitumen from the subsurface and result in degradation of the land upon which they ar...
The number of wells fracked grew significantly, reached 3000 wells per month by the mid 1950s. During the 1970s, there was a huge proliferation of massive hydraulic fracturing, resulted in an enormous number of wells that were stimulated by fracking. By the late 1970s, the process was widely used all different countries and religions, including Canada, Germany, Netherlands and England. It was not until 1999 that scientists found a new method to apply high pressure fluids to rubblize hard-rock formations and extract oil and gas trapped inside. Also, with the invention and application of horizontal drilling to fracking, it became possible to extract larger amounts of oil and natural gas from fracking shales. This absolutely has brought a revolution for the oil and gas industry of the U.S and changed the U.S energy picture from scarcity to abundance. Producers and drillers are now able to exploit a huge amount of natural gas and oil that were locked away in shells and hard rock formations previously. According to many credible reports, about 90 percent of today’s producing wells are stimulated by fracking; up to 35 percent of U.S natural gas production is from shale gas, compares with only 2 percent ten
In erstwhile decades, the economic practice of oil production has perennially been subjugated to the Middle East. However, the rise of domestic production of crude oil and natural gas from shale in the United States has culminated in the passing of Saudi Arabia in terms of oil production. This economic milestone is owed in due part to a relatively-recent implementation of hydraulic fracturing, commonly referred to as “fracking.” According to Aaron Herridge of Shale Gas España, hydraulic fracturing is “…an effective method of extracting natural gas (and oil) from natural shale formations.” In the process, a well cased in steel is injected with millions of pounds of “fracture fluid,” a mixture of water, sand, and chemicals, and the resulting pressure compels shale rock to create fissures, allowing for natural gas to be pumped back to the surface, along with fracture fluids. In fact, the chemicals in fracture fluid are the catalysts for environmental ramifications. When coinciding with oil spills and dangerous natural compounds, the negatives outweigh the positives. Despite hydraulic fracturing’s auspicious impact upon the U.S.’s production of oil, it poses as a significant threat to the health of the environment; through the proliferation of fractured wells, the use of dangerous chemicals, and high numbers of oil spills, water contamination, land damage, and air pollution have resulted.
As we have discussed, petroleum, natural gas, and its industries are a major factor in our economy. Oil and natural gas’s history, operations, environmental impacts, and present and future challenges demonstrate the importance of these non-renewable natural resources. The exploration of oil will continue to expand through the study of geoscience, engineering, and most importantly, technology. Midstream, containing the main operations of oil and gas, is improving each year in efficient processes for transporting, refining, and storing oil and gas. Despite the numerous challenges that are faced in the petroleum and gas industry, geologists continue to strive to make their operations safer for the environment, but are these efforts enough to save our planet for our future generations?