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The Bakken formation is a rock unit from the Late Devonian to Early Mississippian age occupying about 200,000 square miles (520,000 km2) of the subsurface of the Williston Basin, underlying parts of Montana, North Dakota, Saskatchewan and Manitoba. The formation was initially described by geologist J.W. Nordquist in 1953. The formation is entirely in the subsurface, and has no surface outcrop. It is named after Henry Bakken, a farmer in Tioga, North Dakota who owned the land where the formation was initially discovered, during drilling for oil. Besides being a widespread prolific source rock for oil when thermally mature, significant producible oil reserves exist within the Bakken formation itself. Oil was first discovered within the Bakken in 1951, but past efforts to produce it have faced technical difficulties. In April 2008, a USGS report estimated the amount of recoverable oil using technology readily available at the end of 2007 within the Bakken Formation at 3.0 to 4.3 billion barrels (680,000,000 m3), with a mean of 3.65 billion. Simultaneously the state of North Dakota released a report with a lower estimate of 2.1 billion barrels (330,000,000 m3) of technically recoverable oil in the Bakken. Various other estimates place the total reserves, recoverable and non-recoverable with today’s technology, at up to 24 billion barrels. A recent estimate places the figure at 18 billion barrels. In April 2013, the US Geological Survey released a new figure for expected ultimate recovery of 7.4 billion barrels of oil.
The application of hydraulic fracturing and horizontal drilling technologies have caused a boom in Bakken production since 2000. By the end of 2010, oil production rates had reached 458,000 barrels (72,800 m3) per day, thereby outstripping the pipeline capacity to ship oil out of the Bakken. There is some controversy over the safety of shipping it by rail. This was illustrated by the 2013 Lac-MĂŠgantic rail disaster in which a unit train carrying 77 tank cars full of highly volatile Bakken oil through Quebec from North Dakota to the Irving Oil Refinery in New Brunswick derailed and exploded in the town centre of Lac-MĂŠgantic, destroying 30 buildings (half the downtown core) and killing 47 people. The explosion was estimated to have a 1-kilometre (0.62 mi) blast radius. As of January 2015, estimates varied on the break-even oil price for drilling Bakken wells. The North Dakota Department of Natural Resources estimated overall break-even to be just below US$40 per barrel. An analyst for Wood McKenzie said that the overall break-even price was US$62/barrel, but in high-productivity areas such as Sanish Field and Parshall Oil Field, the break-even price was US$38US$40 per barrel. The rock formation consists of three members: lower shale, middle dolomite, and upper shale. The shales were deposited in relatively deep anoxic marine conditions, and the dolomite was deposited as a coastal carbonate bank during a time of shallower, well-oxygenated water. The middle dolomite member is the principal oil reservoir, roughly two miles (3.2 km) below
the surface. Both the upper and lower shale members are organic-rich marine shale. The Bakken formation has emerged in recent years as one of the most important sources of new oil production in the United States. Most Bakken drilling and production has been in North Dakota, although the formation also extends into Montana and the Canadian provinces of Saskatchewan and Manitoba. As of 2013, the Bakken was the source of more than ten percent of all US oil production. By April, 2014 Bakken production in North Dakota and Montana exceeded 1 million barrels per day (160,000 m3/d). As a result of increased production from the Bakken, and long term
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production declines in Alaska and California, North Dakota as of 2014 was the second largest oil-producing state in the US, behind only Texas in volume of oil produced. Bakken production has also increased in Canada, although to a lesser degree than in the US, since the 2004 discovery of the Viewfield Oil Field in Saskatchewan. The same techniques of horizontal drilling and multi-stage massive hydraulic fracturing are used. In December 2012, 2,357 Bakken wells in Saskatchewan produced a record high of 71,000 barrels per day (11,000 m3/d). The Bakken Formation also produces in ManiWorld Views Guides
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toba, but the yield is small, averaging less than 2,000 barrels per day (300 m3/d) in 2012. Drilling and completion Most Bakken wells are drilled and completed in the middle member. Many wells are now being drilled and completed in the basal Sanish/ Pronghorn member and in the underlying Three Forks Formation, which the North Dakota Department of Mineral Resources treats as part of the Bakken for oil production statistical purposes. Porosities in the Bakken averages about 5%, and permeabilities are very low, averaging 0.04 millidarcies—much lower than typical oil reservoirs, in today’s terms a light tight oil play. However, the presence of vertical to sub-vertical natural fractures makes the Bakken an excellent candidate for horizontal drilling techniques in which a well is drilled horizontally along bedding planes, rather than vertically through them. In this way, a borehole can contact many thousands of feet of oil reservoir rock in a unit with a maximum thickness of only about 140 feet (40 m). Production is also enhanced by artificially fracturing the rock, to allow oil to seep to the oil well.
Bakken oil is “sweet,” meaning that it has little or no hydrogen sulfide. The academic community commented in 2011 that increased concentration of H2S had been observed in the Bakken field and presented challenges such as “health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements”. Hydraulic fracturing in the United States Increased US oil production from hydraulically fractured tight oil wells was mostly responsible for the decrease in US oil imports since 2005 (decreased oil consumption was also an important component). The US imported 52% of its oil in 2011, down from 65% in 2005. Hydraulically fractured wells in the Bakken, Eagle Ford, and other tight oil targets, enabled US crude oil production to rise in September 2013 to the highest output since 1989. Hydraulic fracturing in Canada Massive hydraulic fracturing has been widely used in Alberta since
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the late 1970s.:1044 The method is currently used in development of the Cardium, Duvernay, Montney and Viking formations in Alberta, Bakken formation in Saskatchewan, Montney and Horn River formations in British Columbia. History of Bakken oil resource estimates Oil in place A research paper by USGS geochemist Leigh Price in 1999 estimated the total amount of oil contained in the Bakken shale ranged from 271 billion to 503 billion barrels (8.00×1010 m3), with a mean of 413 billion barrels (6.57×1010 m3). While others before him had begun to realize that the oil generated by the Bakken shales had remained within the Bakken, it was Price, who had spent much of his career studying the Bakken, that particularly stressed this point. If he was right, the large amounts of oil remaining in this formation would make it a prime oil exploration target. Price died in 2000 before his research could be peer-reviewed and published. The drilling and production successes in much of the Bakken beginning with the Elm Coulee Oil Field discovery in 2000 have proven correct his claim that the oil generated by the Bakken shale was there. In April 2008, a report issued by the state
of North Dakota Department of Mineral Resources estimated that the North Dakota portion of the Bakken contained 167 billion barrels (2.66×1010 m3) of oil in place. Recoverable oil Although the amount of oil in place is a very large oil resource, the percentage that can be extracted with current technology is another matter. Estimates of the Bakken’s recovery factor have ranged from as low as 1% — because the Bakken shale has generally low porosity and low permeability, making the oil difficult to extract — to Leigh Price’s estimate of 50% recoverable. Reports issued by both the USGS and the state of North Dakota in April 2013 estimates up to 7.4 billion barrels of oil can be recovered from the Bakken and Three Forks formations in the Dakotas and Montana, using current technology. The flurry of drilling activity in the Bakken, coupled with the wide range of estimates of in-place and recoverable oil, led North Dakota senator Byron Dorgan to ask the USGS to conduct a study of the Bakken’s potentially recoverable oil. In April 2008 the USGS released this report, which estimated the amount of technically recoverable, undiscovered oil in the Bakken formation at 3.0 to 4.3 billion barrels (680,000,000 m3),
with a mean of 3.65 billion. Later that month, the state of North Dakota’s report estimated that of the 167 billion barrels (2.66×1010 m3) of oil in-place in the North Dakota portion of the Bakken, 2.1 billion barrels (330,000,000 m3) were technically recoverable with current technology. In 2011, a senior manager at Continental Resources Inc. (CLR) declared that the “Bakken play in the Williston basin could become the world’s largest discovery in the last 30-40 years”, as ultimate recovery from the overall play is now estimated at 24 billion bbls. (Note: the recent discoveries off the coast of Brazil should be greater, with proven reserves of 30 billion, and a potential for 50 to 80.) This considerable increase has been made possible by the combined use of horizontal drilling, hydraulic fracturing, and a large number of wells drilled. While these technologies have been consistently in use since the 1980s, the Bakken trend is the place where they are being most heavily used: 150 active rigs in the play and a rate of 1,800 added wells per year. An April 2013 estimate by the USGS projects that 7.4 billion barrels of undiscovered oil can be recovered from the Bakken and Three Forks formations and 6.7
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trillion cubic feet of natural gas and 530 million barrels of natural gas liquids using current technology. The Energy Information Administration (EIA), the statistics service of the Department of Energy, estimated in 2013 that there were 1.6 billion barrels and 2.2 trillion cubic feet (tcf) of technically recoverable oil and natural gas in the Canadian portion of the Bakken formation. Crescent Point Energy and other operators are implementing waterfloods in the Bakken Formation of the Viewfield Oil Field in Saskatchewan. Some believe that waterflooding can raise the recovery factor at Viewfield from 19 percent to more than 30 percent, adding 1.5 to two billion barrels of additional oil. Proved reserves The US EIA reported that proved reserves in the Bakken/Three Forks were 2.00 billion barrels of oil as of 2011. History of Bakken Oil The Bakken formation has produced oil since 1953, when a North Dakota well was completed in the Bakken. The 2000 discovery of the Elm Coulee Oil Field, Richland County, Montana, where production is expected to ultimately total 270 million barrels (43,000,000 m3) drew a great deal of attention to the World Views Guides
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trend where oil was trapped along the Bakken pinchout. In 2007, production from Elm Coulee averaged 53,000 barrels per day (8,400 m3/d) — more than the entire state of Montana a few years earlier. The Mondak Field to the southeast of Elm Coulee extended the productive pinchout trend into North Dakota. Elm Coulee was key to later Bakken development because it combined horizontal wells and hydraulic fracturing, and targeted the dolomitic middle Bakken member rather than the shales of the upper or lower Bakken. New interest developed in 2006 when EOG Resources reported that a single well it had drilled into an oil-rich layer of shale near Parshall, North Dakota was anticipated to produce 700,000 barrels (110,000 m3) of oil. At Parshall, the abrupt eastern limit of the field is formed by the extent of thermally mature Bakken shale; shale farther east is thermally immature. The Parshall Oil Field discovery, combined with other factors, including an oil-drilling tax break enacted by the state of North Dakota in 2007, shifted attention in the Bakken from Montana to the North Dakota side. The number of wells drilled in the North Dakota Bakken jumped from 300 in 2006 to 457 in 2007. The viability of the play in North
Dakota west of the Nesson Anticline was uncertain until 2009, when Brigham Oil & Gas achieved success with larger hydraulic fracturing treatments, with 25 or more stages. According to North Dakota government statistics, daily oil production per well seems to have peaked (or at least reached a plateau) at 145 barrels in June 2010. Although the number of wells doubled between June 2010 and December 2011, oil production per well remains essentially unchanged. However, total oil produced continues to increase, as more wells are brought online. Exploration and production A number of publicly traded oil and gas companies have drilling rigs in the Bakken trend. These include EOG Resources Inc., Continental Resources Inc., Whiting Oil & Gas Inc., Marathon Oil Corporation, QEP Resources, Hess Corporation, Samson Oil and Gas Ltd, In Canada, operators include Lightstream Resources (formerly PetroBakken Energy), Crescent Point Energy, and Tundra Oil & Gas Partnership. There are several companies whose Bakken holdings and tight oil expertise may have made them attractive takeover targets. XTO Energy was bought by ExxonMobil in 2010. The Norwegian company Statoil bought Brigham Exploration in 2011.
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Analysts expect that $16 billion will be spent on further developing Bakken fields in 2015. The large increase in tight oil production is one of the reasons behind the price drop in late 2014. Oil and gas infrastructure The great increases in oil and gas production have exceeded the areas’s pipeline capacity to transport hydrocarbons to markets. There is only one refinery in the area. As a result the oil and gas prices received have been much lower than the normal North American index prices of West Texas Intermediate for oil and Henry Hub for gas. The shortage of pipeline capacity has caused some producers to ship oil out of the area by more expensive methods of truck or railroad. It was Bakken crude oil carried by train that caught fire in the deadly 2013 Lac-Mégantic rail disaster in Quebec. Part of the disaster at Lac-Mégantic has been blamed on the fact that much of the highly volatile Bakken oil was mislabeled as lower risk oil and was being shipped in substandard tank cars not designed to contain it. Because of the shortage of pipeline capacity out of state, over half of North Dakota’s production is sent to market by rail. BNSF Railway and Canadian Pacific Railway told Minnesota officials that about 50 Bakken oil trains pass through the state each
week, mostly through the Twin Cities of Minneapolis–Saint Paul. At least 15 major accidents involving crude oil or ethanol trains have occurred in the United States and Canada since 2006, and most small cities such as Lac-Megantic are not prepared for oil train explosions and fires. In March 2013, Canadian pipeline company Enbridge completed a pipeline to take North Dakota oil north into Canada, where it hooks up to Enbridge’s main pipeline delivering western Canadian oil to refineries in the American Midwest. Unlike the stalled crossborder Keystone XL Pipeline, the pipeline project to carry American crude across the border was approved by the US government without controversy. Absent the infrastructure to produce and export natural gas, it is merely burned on the spot; a 2013 study estimated the cost at $100 million per month. Effects of the boom The oil boom has given those who own mineral rights large incomes from lease bonuses and royalties. The boom has reduced unemployment and given the state of North Dakota a billion-dollar budget surplus. North Dakota, which ranked 38th in per capita gross domestic product (GDP) in 2001, rose steadily with the Bakken boom, and now has per capita GDP 29% above the national average. The industrialization and population boom has put a strain on water supplies, sewage systems, and government services of the small towns and ranches in the area. Increasing economic prosperity has also brought increasing crime and social problems.
North Dakota oil boom is an ongoing period of rapidly expanding oil extraction from the Bakken formation in the state of North Dakota that followed the discovery of Parshall Oil Field in 2006, and is continuing as of 2015. Despite the Great Recession, the oil boom has resulted in enough jobs to give North Dakota the lowest unemployment rate in the United States. The boom has given the state of North Dakota, a state with a 2013 population of about 725,000, a billion-dollar budget surplus. North Dakota, which ranked 38th in per capita gross domestic product (GDP) in 2001, rose steadily with the Bakken boom, and now has per capita GDP 29% above the national average. There are three reasons for the oil boom, not just in North Dakota but nationwide: the recent discoveries of shale gas reserves in the United States initiatives to seek independence from unstable energy sources, such as Venezuela and nations in the Middle East the successful use of horizontal drilling and hydraulic fracturing, which have made energy deposits recoverable The leases expire after their primary term, commonly three to five years, unless the lessee oil company drills and starts producing, in which case the leases continue as long as oil and gas are continually produced. Expiring leases result in a push to commence drilling and production on as many as possible before they expire.
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Environmentally Friendly Ways of Reusing and Recycling Paper, Books and Mags by: Reuben Frye
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s consumers demand the need for more paper, whether it’s for newspapers, plain paper or books, we continue to cut down vast numbers of really old trees. It will take numerous years to see this turned over. Reusing and recycling paper is really important nowadays.
All paper, including books and magazines, are virtually wholly biodegradable, meaning they don’t clog landfills for many years and will merely degrade into nothing. The fact that there is a need for more paper makes it appear daft not to recycle as much as we possibly can. That is why we should reuse and recycle.
that the paper can be usable There are always places like once again, the recycling libraries that are happy to process should be put in take your old books from place. This saves the trees and you. Some libraries will take makes for a healthy envidonations of old books and ronment. Paper recycling is even magazines, providing not always straightforward they are in good condition. and can be made challengThe library and the pubing by the stapling of books lic will be more glad since and mags. Magnets may be they will have more reading utilized to handle the prob- choices. So instead of merely lems of metal and recycling tossing a book or leaving it to companies are constantly collect dust, think about giving it to a library.
try to find ways to better the process.
Mags and books can be reThe traditional means of used, it is only a matter of recycling paper is by making using our imagination. Those use of recycling facilities. You old books and magazines are will observe that where you a fantastic learning resource dwell, there are opportunifor your kids and they will ties to recycle, including in have the chance to give them numerous cases your local to other people in the future. grocery store. You may notice An old book will be of use to that your local area has difsomebody else and it is not ferent bins so you can sort hard for us give it this way. your paper for recycling. So
Books can also be sold instead of given away either locally or online. EBay and Amazon are popular places online where you can try selling your old books. To sum it up, paper is being utilized more and more but fewer trees. Beasts use trees as a natural home ground and they are essential for the wellbeing of the environment. There are plenty of choices for us to recycle paper and to ensure that books and magazines are reused instead of thrown away.
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Hydraulic fracturing (also hydrofracturing, hydrofracking, fracking or fraccing), is a wellstimulation technique in which rock is fractured by a hydraulically pressurized liquid made of water, sand, and chemicals. Some hydraulic fractures form naturally—certain veins or dikes are examples.A high-pressure fluid (usually chemicals and sand suspended in water) is injected into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open. Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. As of 2012, 2.5 million “frac jobs” had been
performed worldwide on oil and gas wells; over one million of those within the U.S. Such treatment is generally necessary to achieve adequate flow rates in shale gas, tight gas, tight oil, and coal seam gas wells. Hydraulic fracturing is highly controversial; whereas its proponents advocate the economic benefits of more extensively accessible hydrocarbons, its environmental impacts include the risk of contaminating ground water, depletion of fresh water, degradation of the air quality, the potential triggering of earthquakes, noise pollution, surface pollution, and the consequential risks to health and the environment. Increases in seismic activity following hydraulic fracturing along dormant or previously unknown faults are sometimes caused by the deep-injection disposal of hydraulic fracturing flowback (a byproduct of hydraulically fractured wells), and produced formation brine (a byproduct of both fractured and nonfractured oil and gas wells). For these reasons, hydraulic fracturing is under international scrutiny, restricted
in some countries, and banned altogether in others. Some of those countries, notably the U.K., contemplated repeal of bans on hydraulic fracturing in favor of regulation. The European Union is drafting regulations that would permit controlled application of hydraulic fracturing. Mechanics Fracturing in rocks at depth tends to be suppressed by the pressure due to the weight of the overlying rock strata, and the cementation of the formation. This is particularly significant in “tensile” (Mode 1) fractures which require the walls of the fracture to move against this pressure. Fracturing occurs when effective stress is overcome by the pressure of fluids within the rock. The minimum principal stress becomes tensile and exceeds the tensile strength of the material. Fractures formed in this way are generally oriented in a plane perpendicular to the minimum principal stress, and for this reason, hydraulic fractures in well bores can be used to determine the orientation of stresses. In natural examples, such as dikes or vein-filled fractures, the orientations can be used to infer past states of stress. Veins Most mineral vein systems are a result of repeated natural fractur-
ing during periods of relatively high pore fluid pressure. This is particularly evident in “crackseal” veins, where the vein material is part of a series of discrete fracturing events, and extra vein material is deposited on each occasion. One example of long-term repeated natural fracturing is in the effects of seismic activity. Stress levels rise and fall episodically, and earthquakes can cause large volumes of connate water to be expelled from fluid-filled fractures. This process is referred to as “seismic pumping”. Dikes Minor intrusions in the upper part of the crust, such as dikes, propagate in the form of fluid-filled cracks. In such cases, the fluid is magma. In sedimentary rocks with a significant water content, fluid at fracture tip will be steam. Shales Due to shale’s high porosity and low permeability, technological research, development and demonstration were necessary before hydraulic fracturing was accepted for commercial application to shale gas deposits. In 1976, the United States government started the Eastern Gas Shales Project, a set of dozens of public-private hydraulic fracturing demonstration projects. During the same period, the Gas Research Institute, a gas industry research consortium, received approval for research and funding from the Federal Energy Regulatory Commission. In 1997, taking the slickwater fracturing technique used in East Texas by Union Pacific Resources (now part of Anadarko Petroleum Cor-
poration), Mitchell Energy (now part of Devon Energy), applied the technique in the Barnett Shale of north Texas. This made gas extraction widely economical in the Barnett Shale, and was later applied to other shales. George P. Mitchell has been called the “father of fracking” because of his role in applying it in shales. The first horizontal well in the Barnett Shale was drilled in 1991, but was not widely done in the Barnett until it was demonstrated that gas could be economically extracted from vertical wells in the Barnett. As of 2013, massive hydraulic fracturing is being applied on a commercial scale to shales in the United States, Canada, and China. Several additional countries are planning to use hydraulic fracturing. Hydraulic fracturing is used to increase the rate at which fluids, such as petroleum, water, or natural gas can be recovered from subterranean natural reservoirs. Reservoirs are typically porous sandstones, limestones or dolomite rocks, but also include “unconventional reservoirs” such as shale rock or coal beds. Hydraulic fracturing enables the extraction of natural gas and oil from rock formations deep below the earth’s surface (generally 2,000–6,000 m (5,000–20,000 ft)), which is greatly below typical groundwater reservoir levels. At such depth, there may be insufficient permeability or reservoir pressure to allow natural gas and oil to flow from the rock into the wellbore at high economic return. Thus, creating conductive fractures in the rock is instrumental in extraction from naturally impermeable shale reservoirs. Permeability is measured in the microdarcy to nanodarcy range. Fractures are a conductive path connecting a larger volume of reservoir to the well. So-called “super fracking,” creates cracks deeper in the rock formation to release more oil and gas, and increases efficiency. The yield for typical shale bores generally falls off after the first year or two, but the peak producing life of a well can be extended to several
decades. While the main industrial use of hydraulic fracturing is in stimulating production from oil and gas wells, hydraulic fracturing is also applied: To stimulate groundwater wells To precondition or induce rock cave-ins mining As a means of enhancing waste remediation, usually hydrocarbon waste or spills To dispose waste by injection deep into rock To measure stress in the Earth For electricity generation in enhanced geothermal systems To increase injection rates for geologic sequestration of CO 2 Since the late 1970s, hydraulic fracturing has been used, in some cases, to increase the yield of drinking water from wells in a number of countries, including the US, Australia, and South Africa.
Directional drilling (or slant drilling) is the practice for drilling non-vertical wells. It can be broken down into three main groups: oilfield directional drilling, utility installation directional drilling (horizontal directional drilling), directional boring, and surface in seam (SIS), which horizontally intersects a vertical well target to extract coal bed methane. History Many prerequisites enabled this suite of technologies to become productive. Probably, the first requirement was the realization that oil wells, or water wells, are not necessarily vertical. This realization was quite slow, and did not really grasp the attention of the oil industry until the late 1920s when there were several lawsuits alleging that wells drilled from a rig on one property had crossed the boundary and were penetrating a reservoir on an adjacent property.[citation needed] Initially, proxy evidence such as production changes in other wells was accepted, but such cases fueled the development of small diameter tools capable of surveying wells during drilling. Horizontal directional drill rigs are developing towards large-scale, micro-miniaturization, mechanical automation, hard stratum working, exceeding length and depth oriented monitored drilling.[1] Measuring the inclination of a wellbore (its deviation from the vertical) is comparatively simple, requiring only a pendulum. Measuring the azimuth (direction with respect to the geographic grid in which the wellbore was running from the vertical), however, was more difficult. In certain circumstances, magnetic fields could be used, but would be influenced by metalwork used inside wellbores, as well as the metalwork used in drilling equipment. The next advance was in the modification of small gyroscopic compasses by the Sperry Corporation, which was making similar compasses for aeronautical navigation. Sperry did this under contract to Sun Oil (which was involved in a law-
suit as described above), and a spin-off company “Sperry Sun” was formed, which brand continues to this day,[when?][clarification needed] absorbed into Halliburton. Three components are measured at any given point in a wellbore in order to determine its position: the depth of the point along the course of the borehole (measured depth), the
inclination at the point, and the magnetic azimuth at the point. These three components combined are referred to as a “survey”. A series of consecutive surveys are needed to track the progress and location of a wellbore. Prior experience with rotary drilling had established several principles for the configuration of drilling equipment down hole (“Bottom Hole Assembly” or “BHA”) that would be prone to “drilling crooked hole” (i.e., initial accidental deviations from the vertical would be increased). Counterexperience had also given early directional
drillers (“DD’s”) principles of BHA design and drilling practice that wouldhelp bring a crooked hole nearer the vertical. In 1934, H. John Eastman &Roman W. Hines Long Beach, California, became pioneers in directional drilling when they and George Failing of Enid, Oklahoma, saved the Conroe, Texas, oil field. Failing had recently patented a portable drilling truck. He had started his company in 1931 when he mated a drilling rig to a truck and a power take-off assembly. The
innovation allowed rapid drilling of a series of slanted wells. This capacity to quickly drill multiple relief wells and relieve the enormous gas pressure was critical to extinguishing the Conroe fire. In a May, 1934, Popular Science Monthly article, it was stated that “Only a handful of men in the
world have the strange power to make a bit, rotating a mile below ground at the end of a steel drill pipe, snake its way in a curve or around a dogleg angle, to reach a desired objective.” Eastman Whipstock, Inc., would become the world’s largest directional company in 1973.[citation needed] Combined, these survey tools and BHA designs made directional drilling possible, but it was perceived as arcane. The next major advance was in the 1970s, when downhole drilling motors (aka mud motors, driven by the hydraulic power of drilling mud circulated down the drill string) became common. These allowed the drill bit to continue rotating at the cutting face at the bottom of the hole, while most of the drill pipe was held stationary. A piece of bent pipe (a “bent sub”) between the stationary drill pipe and the top of the motor allowed the direction of the wellbore to be changed without needing to pull all the drill pipe out and place another whipstock. Coupled with the development of measurement while drilling tools (using mud pulse telemetry, networked or wired pipe or EM telemetry, which allows tools down hole to send directional data back to the surface without disturbing drilling operations), directional drilling became easier. Certain profiles cannot be drilled while the drill pipe is rotating. Drilling directionally with a downhole motor requires occasionally stopping rotation of the drill pipe and “sliding” the pipe through the channel as the motor cuts a curved path. “Sliding” can be difficult in some formations, and it is almost always slower and therefore more expensive than drilling while the pipe is rotating, so the ability to steer the bit while the drill pipe is rotating is desirable. Several companies have developed tools which allow directional control
while rotating. These tools are referred to as rotary steerable systems (RSS). RSS technology has made access and directional control possible in previously inaccessible or uncontrollable formations.