The Natural Gas Gathering Process
With a huge recent investment in natural gas reclamation, America has seen a recent upsurge in the amount of natural gas being produced. In 2009 America became the largest producer of dry natural gas in the world. As of the end of 2016, figures show that almost 25% of the world’s gas is being produced in the U.S. which places the country in a strong financial position, especially considering that America is also the largest consumer of Natural gas in the world. With the development of the gas industry, new techniques have become widespread in the business of harvesting natural resources as companies have needed to find modern methods of mining.
The Evolution of Natural Gas Extraction
Until recent years, capturing natural gas was always a very hazardous operation, which resulted in it being a dangerous and very expensive process to remove and transport this resource from the gas fields within the earth. Therefore consumption and reclamation of natural gas wasn’t as widespread as with other fossil fuels such as oil and coal. Despite the fact that gas fields are more often found in close proximity to oil deposits, gas fields were historically often vented into the atmosphere rather than harvested for consumption, due to the relatively high cost of capturing these gasses. This was partly altered when the market value of natural gas increased, thus making the product of higher value to the oil and gas companies. But with advances in technology that allows for greater accuracy in geological mapping, the entire process has become much more viable as an enterprise. Once a natural gas reserve has been identified using various modern exploration methods, the gas then needs to be safely extracted from the ground before it can be refined and used as an energy supply. This is an area of gas production which has also benefited from new technologies.
The most common and conventional method of achieving this is through a process of vertical drilling, which is literally the act of digging a hole directly from the earth’s surface to the fossil fuel below. Once contacted, the reserve can then be piped to the surface where it is then refined from the raw gas, which usually consists of either:
- Dry gas – The majority of American gas wells produce gas streams that have a high percentage of methane, and therefore require minimal amounts of processing to remove impurities such as water, carbon dioxide and sulphur.
- Wet gas – In addition to the impurities found in dry gas, natural gas liquids (NGL’s) such as butane, ethane, and propane are present and this requires further refinement to separate these hydrocarbons before they can be sold for their respective uses.
- Sour gas – When hydrogen sulfide is present in the gas, this causes a further complication due to its toxic and corrosive characteristics. Developments in refinement processing and corrosion resistant materials now allow for sour gas to be an economically viable option.
Once retrieved and refined, the natural gas can then be stored or transported across the country through a natural gas pipeline network. This safely distributes the gas through a series of pressurized routes to any given part of the country.
Advanced Drilling Techniques
The main disadvantage with vertical drilling is that it is limited to extracting only the gas that is located directly below the well due to the non-uniform shape of the deposits. This results in many vertical wells being required to access the whole of an underground source. It creates both an unsightly blemish on the landscape, additional financial costs from digging multiple wells and there can also be problems in reaching areas of the gas field, which are covered by a layer of high-density rock such as shale. One way in which this has been overcome is with new technologies, such as horizontal drilling. It allows a vertical well to be expanded from a kicking-off point under the earth’s surface to send the pipeline in a chosen direction. This allows a greater area to be reached from the single well site with the extended legs, capable of stretching for over a mile in length. A development on this principle is multilateral drilling, which grants for numerous legs to be created from the central bore hole. Coupled with advances in extended reach drilling, these new techniques provide access to greater areas of the gas field that can then be successfully harvested from a small surface footprint.
Improved Recovery of Natural Gas
In a separate development from the boring technologies which enables complex path drilling, another modern technology which has greatly improved the effectiveness of gathering natural gas from underground reserves is the amount of gas that can be retrieved from them. The initial contact of the bore hole with the gas field will result in a primary recovery, which is due to the gas field being a pressurized environment. This forces the gas up the well into an area of reduced pressure through forces of equalization. Due to the difference in nature between gas and liquid, natural gas provides a higher yield in this primary stage in comparison to crude oil. However, the amount of gas which is extracted is often only between 50 – 90% of the total gas in the reservoir. To improve this efficiency rate, a secondary recovery stage can be applied to gather more product by injecting a high-pressure gas into the well and below the reservoir to force the remaining natural gas out of the ground. This has only recently become common practice, as the market value of natural gas has increased which makes the additional process economically viable.
Modern Extractions of Fossil Fuels
The increased financial value of natural gas has also lead to many other developments, as more companies look to exploit the resources that are still being uncovered. With the expansion of the natural gas industry, more techniques are being designed and implemented such as hydraulic fracturing, or fracking. Fracking is the use of a highly pressurized fluid such as water to break through hard rock structures in the ground that prevent the gas field being reached, using conventional drilling techniques. Another commonly used method of reaching the fossil fuel and improving the pathway to the supply reserves is acidizing. This is the use of a corrosive acid, most often using hydrochloric acid, to either dissolve obstructions such as rock from the path or to clean the bore hole of an old well that is to be re-opened.
Despite both of these practices receiving concerns from some quarters which has seen fracking in particular, being banned in some areas of the world, studies have shown that there are no major problems incurred through utilizing these processes. With safety concerns being of paramount importance within the fossil fuel industry, the use of modern materials and equipment have actually resulted in a decrease in the number of leakages and pollution spills into the local environment.
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