Fossil

Williston Basin

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bakken Formation Reserve Estimates
Julie LeFever and Lynn Helms
Executive Summary
Nature of the Controversy

All researchers agree that the Bakken Formation is a tremendous source rock. The controversy
lies with how much oil has been generated, what other formations it may have sourced, and how
much is ultimately recoverable. Early research on the Bakken started with a 1974 landmark paper
by Wallace Dow, a UND Geology graduate, that addressed the oil generation capacity of the
Bakken shale. Since that time, several additional papers have re-evaluated the Bakken, each
bringing its own controversy over how much oil the Bakken is capable of generating and more
importantly, how much of that oil can be economically produced.
The current controversy involves a paper by the late Dr. Leigh Price formerly of the United States
Geological Survey in Denver, Colorado. He was an innovative thinker that challenged many of
the traditional viewpoints of petroleum geochemistry. After an extensive oil sampling program
by the North Dakota Geological Survey showed oil from the Bakken is compositionally distinct,
further work, additional analyses, and many discussions with Dr. Price resulted in the
controversial paper under review.

The methods used by Price to determine the amount of hydrocarbons generated by the Bakken
and the idea that the oil has not migrated out of the Bakken are under dispute.

History of Bakken Oil Generation Estimates
A landmark paper by Dow and a companion paper by Williams (1974) recognized the Bakken as
a tremendous source for the oil produced in the Williston Basin. These papers suggested that the
Bakken was capable of generating 10 billion barrels of oil (BBbls). Webster (1982, 1984) as part
of a Master’s Thesis at the University of North Dakota further sampled and analyzed the Bakken
and calculated hydrocarbon generation capacities to be about 92 BBbls. This data was updated
by Schmoker and Hester (1983) who estimated that the Bakken was capable of generating 132
BBbls of oil in North Dakota and Montana. Price (unpublished) used a more complete database
and estimated that the Bakken was capable of generating between 271 and 503 BBbls of oil with
an average of 413 BBbls. New estimates of the amount of hydrocarbons generated by the Bakken
were presented by Meissner and Banks (2000) and by Flannery and Kraus (2006). The first of
these papers tested a newly developed computer model with existing Bakken data to estimate
generated oil of 32 BBbls. The second paper used a more sophisticated computer program with
extensive data input supplied by the ND Geological Survey and Oil and Gas Division. Early
numbers generated from this information placed the value at 200 BBbls later revised to 300
BBbls when the paper was presented in 2006.

North Dakota Geological Survey Input
Dr. Price was impressed by the data available from the State of North Dakota and the extensive
oil sampling program conducted by the North Dakota Geological Survey which determined oil
from the Bakken is compositionally distinct from oil generated in the Mission Canyon Formation
(Madison). The results of this study were published by Price and LeFever in 1994 and showed
that the Bakken is “truly dysfunctional” with no evidence in the analysis that Bakken-generated
oil had migrated into the overlying Madison beds, as previously thought. Therefore, the oil
generated by the Bakken remains within the Bakken. Considerable input was given to the Price
paper by North Dakota Geological Survey geologists concerning the overall geology of the
Williston Basin and specifically the Bakken Formation. Price used samples collected for analysis
from the ND Geological Survey Core and Sample Library and the well files from the Oil and Gas
Division extensively.

North Dakota Geological Survey Evaluation
The geochemistry methods used by Dr. Price are beyond the expertise of the Geological Survey
to review; however his methods appear to be supported by the data and are adequately explained.
The geological model as presented by Price in his paper appears solid. Use of North Dakota
Geological survey and Oil and Gas division data along with considerable input from staff
geologists adds to the credibility of the geological portion of the model.
Conclusions and Recommendations
The Bakken Formation is a large unconventional resource that underlies most of the western
portion of the state of North Dakota.
Shales that comprise the upper and lower members of the Bakken are world class source rocks.
An extensive oil sampling program by the North Dakota Geological Survey shows that the
Bakken generated oil remains in the Bakken.
The geological model presented by Price in his paper appears solid and is built upon considerable
input by North Dakota Geological Survey geologists, samples from the ND Core and Sample
Library, and the well files from the Oil and Gas Division.
A sophisticated computer program with extensive data input supplied by the ND Geological
Survey and Oil and Gas Division places the Bakken generated value at 200 – 300 BBbls.
How much of the generated oil is recoverable remains to be determined. Estimates of 50%, 18%,
and 3 to 10% have been published.
The Bakken play on the North Dakota side of the basin is still early in the learning curve.
Technology and the price of oil will dictate what is potentially recoverable from this formation.
The unpublished manuscript by Dr. Leigh Price entitled “Origins and characteristics of the basincentered
continuous-reservoir unconventional oil-resource base of the Bakken Source System,
Williston Basin” contains valuable information and should be published with a disclaimer or
perhaps a discussion. The data in the paper is valuable and potentially of great benefit to the
state. It should be left to the geological community to determine whether or not they will accept
interpretations presented within the report.
Discussion
The Bakken Formation is a large unconventional resource that underlies the western
portion of the state of North Dakota. It has been an exploration target several times since
oil was discovered in the state. Recent drilling success in the Bakken Formation of

 

Montana (Wall Street Journal, April 5, 2006) has once again focused interest on this
resource. Since the start of the play in Montana in 2001, activity has also increased on
the North Dakota side of the Williston Basin where the majority of the formation exists.
This activity translates into record lease sales of mineral rights and increased drilling.
Information becomes a valuable component of this activity. Drilling results with the
increase in oil prices have attracted new companies into the Williston Basin. Existing
and new companies commonly have staff with limited or no knowledge of the play.
These companies rely on information from the current literature and the state government
to quickly answer their questions. The availability of that data is important, part of which
is the focus of this paper.
In addition to being an exploration target, the Bakken Formation has also been a
focus of research since the early days of exploration. The Williston Basin is the ultimate
geologic laboratory, especially the North Dakota portion of the basin. Since the
discovery of oil in the state occurred late compared to other states, key legislation was
already in place. The state is foremost in data acquisition and storage. The availability of
well information, cores and samples makes the state an ideal laboratory. Early research
on the Bakken started when a landmark paper was written by Wallace Dow, a graduate
from the Geology Department of the University of North Dakota, in 1974 that addressed
the oil generation capacity of the Bakken shale. Since that time, several additional papers
have added to and further refined the information and re-evaluated the Bakken. Each
additional paper brings its own controversy into the discussion of how much oil the
Bakken is capable of generating and, more importantly, how much of that generated oil
can be economically produced. The following discussion is an in-house review of one of
these papers.
As previously stated, the Bakken has been and continues to be a focus of research.
The shales that comprise the upper and lower members of the Bakken are world class
source rocks. Additionally information that is learned in this basin may be applied to
other similar rocks in North America. The fact that the Williston Basin is located in the
middle of a continent and is relatively undisturbed structurally makes it more attractive
for study. It is a simple, more geologically controlled environment for applied research.
All researchers agree that the Bakken Formation is a tremendous source rock. The
controversy lies with how much oil has been generated, what it has sourced, and how
much is ultimately recoverable. The landmark paper by Dow and a companion paper by
Williams (1974) recognized the Bakken as a tremendous source for the oil produced in
the Williston. Based on the limited dataset of the time, these papers suggested that the
Bakken was capable of generating 10 billion barrels of oil (BBbls). They also suggested
that the only 3 BBbls would be recoverable in existing pools. The remainder would be
found in some undiscovered pools with a large portion left in the Bakken unable to
escape. Webster (1982, 1984) as part of a Master’s Thesis at the University of North
Dakota further sampled and analyzed the Bakken and calculated hydrocarbon generation
capacities to be about 92 BBbls. Once again this data was updated by Schmoker and
Hester (1983) who estimated that the Bakken was capable of generating 132 BBbls of oil
in North Dakota and Montana. It is easy to see that as new data become available the
values shift significantly.

 

The current controversy involves a paper by Dr. Leigh Price formerly of the
United States Geological Survey in Denver, Colorado. Price was a well respected
organic geochemist whose primary research interest was the Bakken Formation. He was
impressed by the data available from the State of North Dakota citing it in many of his
publications, for instance in the current publication under review, he states: “The North
Dakota portion of the Williston Basin, which has the larger of the two Bakken HC
kitchens in the basin, has the best rock and oil sample base and well-history file for any
basin, worldwide.” He was an innovative thinker that challenged many of the traditional
viewpoints of petroleum geochemistry. An early paper by Price and others (1984) once
again looked at the oil resources of the Bakken in the U.S. side of the Williston Basin.
They concluded that this was a significant resource and followed the traditional line of
thought that most of the generated oil had been expelled from the formation. Price
changed his opinion about the conclusion to this paper. He felt that the data was solid but
that they had made some erroneous assumptions in the interpretation of that data. This
change occurred when an extensive oil sampling program was done by the North Dakota
Geological Survey. Oil from the Bakken is compositionally distinct from oil generated in
the Mission Canyon Formation (Madison). The intent of this study was to determine
whether oil had migrated from the Bakken into the overlying and very productive
Madison beds. The results of this study were published by Price and LeFever in 1994
and showed that the Bakken was “truly dysfunctional”. There was no evidence in the
analyses of the oil that Bakken-generated oil had migrated into the overlying Madison
beds, as previously thought. Therefore, the oil generated by the Bakken was still within
the Bakken. Further work, additional analyses and many discussions later with the
author, resulted in the paper under review.
The methods used by Price to determine the amount of hydrocarbons generated by
the Bakken are different from the traditional petroleum geochemical practices and are
under dispute. Previous estimates were determined directly from available data and did
not take into account the changes that had already occurred within the rock. These
estimates are calculated from the area (measured) times the thickness (measured) times
the total organic content (TOC, measured by RockEval pyrolysis in the laboratory) times
the percent of organic carbon that has been converted (measured by RockEval). Price
used a more complete database and re-calculated the data based on what he considered
more realistic input parameters. The reasons for these adjustments are beyond the scope
of this review; however his methods appear to be supported by the data and adequately
explained. He estimated that the Bakken was capable of generating between 271 and 503
BBbls of oil with an average of 413 BBbls. Price also re-calculated the data previously
presented by Schmoker and Hester (1983) and Webster (1984); the re-calculated values
also fall within the range stated above. These values combined with the idea that the oil
has not migrated from the Bakken is what is under dispute. Price also states that 50% of
this oil is recoverable (on average, 200 billion barrels of oil).
The model as presented by Price in this paper appears solid. Considerable input
was given to this paper by North Dakota Geological Survey geologists concerning the
geology of the overall geology of the Williston Basin and specifically the Bakken

 

Formation. In addition to samples collected for analysis from the ND Geological Survey
Core and Sample Library, Price used the well files from the Oil and Gas Division
extensively. This data and the considerable input from staff geologists adds to the
credibility of the geological portion of the model.
New estimates of the amount of hydrocarbons generated by the Bakken were
presented by Meissner and Banks (2000) and by Flannery and Kraus (2006). The first of
these papers tested a newly developed computer model with existing Bakken data. Data
used was not as extensive as some of the other studies mentioned in this discussion
therefore estimates of generated oil presented were 32 BBbls. The second paper by
Flannery and Kraus used a more sophisticated computer program with extensive data
input supplied by the ND Geological Survey and Oil and Gas Division. Early numbers
generated from this information placed the value at 200 BBbls (pers. comm. Jack
Flannery, 2005). Estimates had been revised to 300 BBbls when the paper was presented
in 2006. Even if the lower value of 32 BBbls is correct, the amount that may be
potentially recovered from the Bakken is significant.
How much of the oil that has been generated is technically recoverable is still to
be determined. Price places the value as high as 50% recoverable reserves. A primary
recovery factor of 18% was recently presented by Headington Oil Company for their
Richland County, Montana wells. Values presented in ND Industrial Commission Oil
and Gas Hearings have ranged from 3 to 10%. The Bakken play in the North Dakota side
of the basin is still in the learning curve. North Dakota wells are still undergoing
adjustments and modifications to the drilling and completion practices used for this
formation. It is apparent that technology and the price of oil will dictate what is
potentially recoverable from this formation.
The paper under discussion is an unpublished manuscript by Dr. Leigh Price
entitled “Origins and characteristics of the basin-centered continuous-reservoir
unconventional oil-resource base of the Bakken Source System, Williston Basin.” The
manuscript had been sent out for peer review prior to his death as U.S.G.S. protocol
states. It was my understanding that many of the reviews had been returned with
comments and a “publish” statement. It is unknown whether or not those corrections or
comments were addressed by Dr. Price. There has been an outside request for the
U.S.G.S. to publish this manuscript. They have responded that it has not completed the
peer review process and therefore should not be published. The information is valuable
and should be published with a disclaimer or perhaps a discussion. The data is valuable
and of great benefit to the state. It should also be left to the geological community to
determine whether or not they would accept interpretations presented within the report.
References Cited
Dow, W.G., 1974, Application of oil-correlation and source rock data to exploration in
Williston basin: American Association of Petroleum Geologists Bulletin, v. 58, p.
1253-1262.

 

Flannery J. and Kraus, J, 2006, Integrated analysis of the Bakken petroleum system, U.S.
Williston basin: American Association of Petroleum Geologists Search and
Discovery Article #10105
Meissner, F.F. and Banks, R.B., 2000, Computer simulation of hydrocarbon generation,
migration, and accumulation under hydrodynamic conditions – examples from the
Williston and San Juan Basins, USA: American Association of Petroleum
Geologists Search and Discovery Article #40179
Price, L.C. and LeFever, J.A., 1994, Dysfunctionalism in the Williston basin: The mid-
Madison/Bakken petroleum system: Bulletin of Canadian Petroleum Geology, v.
42, no. 2, p. 187-218.
Price, L.C., Ging, T., Daws, T., Love, A., Pawlewicz, M., and Anders, D., 1984, Organic
metamorphism in the Mississippian-Devonian Bakken shale, North Dakota
portion of the Williston basin, in Woodward, J., Meissner, F.F. and Clayton, J.L.,
eds., Hydrocarbon source rocks of the Greater Rocky Mountain Region: Rocky
Mountain Association of Geologists, Denver, CO, p. 83-134.
Schmoker, J.W. and Hester, T.C., 1983, Organic carbon in the Bakken Formation, United
States portion of Williston basin: American Association of Petroleum Geologists
Bulletin, v. 67, no. 12, p. 2165-2174.
Webster, R.L., 1983, Analysis of petroleum source rocks of the Bakken Formation
(Devonian and Mississippian) in North Dakota: unpubl. Masters Thesis,
University of North Dakota, 150p.
Webster, R.L., 1984, Petroleum source rocks and stratigraphy of the Bakken Formation
in North Dakota, in Woodward, J., Meissner, F.F. and Clayton, J.L., eds.,
Hydrocarbon source rocks of the Greater Rocky Mountain Region: Rocky
Mountain Association of Geologists, Denver, CO, p. 57-81.
Williams, J.A., 1974, Characterization of oil types in Williston basin: American
Association of Petroleum Geologists Bulletin, v. 58, p. 1243-1252.

 

BAKKEN FORMATION

From Wikipedia, the free encyclopedia
  (Redirected from Bakken Formation)

The Bakken formation /ˈbɑːkən/ 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 MontanaNorth Dakota, andSaskatchewan. The formation was initially described by geologist J.W. Nordquist in 1953.[2] 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, in a boring for oil.[3]

Besides being a widespread prolific source rock for oil when thermally mature, there are also significant producible reserves of oil within the Bakken formation itself.[4] 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.[5] The state of North Dakota also released a report that month which estimated that there are 2.1 billion barrels (330,000,000 m3) of technically recoverable oil in the Bakken.[6] Various other estimates place the total reserves, recoverable and non-recoverable with today’s technology, at up to 24 billion barrels. The most recent estimate places the figure at 18 billion barrels.[7]

New rock fracturing technology available starting in 2008 has caused a recent boom in Bakken production. By the end of 2010 oil production rates had reached 458,000 barrels (72,800 m3) per day outstripping the capacity to ship oil out of the Bakken.[8][9] The production technology gain has led a veteran industry insider to declare that the USGS estimates are too low.[10]

CONTENTS

[hide]

[EDIT]GEOLOGY

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.

Porosities in the Bakken average 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.[11] However, the presence of vertical to sub-vertical natural fractures makes the Bakken an excellent candidate for horizontal drilling techniques in which a well drills 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).[12] Production is also enhanced by artificially fracturing the rock,[13] to allow oil to seep to the oil well.

[EDIT]HISTORY OF BAKKEN OIL RESOURCE ESTIMATES

A landmark paper by Dow and a companion paper by Williams (1974) recognized the Bakken formation as a major source for the oil produced in the Williston Basin. These papers suggested that the Bakken was capable of generating 10 billion barrels (1.6×109 m3) of oil (BBbls). Webster (1982, 1984) as part of a Master’s thesis at the University of North Dakota further sampled and analyzed the Bakken and calculated the hydrocarbon potential to be about 92 BBbls. These data were updated by Schmoker and Hester (1983) who estimated that the Bakken might contain a resource of 132 BBbls of oil in North Dakota and Montana. 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).[14] 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, who 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. However, Price died in 2000 before his research could be peer-reviewed and published. Nevertheless, 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 still there. New estimates of the amount of hydrocarbons generated by the Bakken were presented by Meissner and Banks (2000) and by Flannery and Kraus (2006). The first of these papers tested a newly developed computer model with existing Bakken data to estimate generated oil of 32 BBbls. The second paper used a more sophisticated computer program with extensive data input supplied by the ND Geological Survey and Oil and Gas Division. Early numbers generated from this information placed the value at 200 BBbls later revised to 300 BBbls when the paper was presented in 2006.”.[15] 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.[6]

Although these numbers would appear to indicate a very large oil resource, the percentage of this oil which might be extracted using current technology is another matter. Estimates of the Bakken’s technically recoverable oil 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.[16] Reports issued by both the USGS and the state of North Dakota in April 2008 seem to indicate the lower range of recoverable estimates are more realistic with 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.[5] Later that month, the state of North Dakota’s report [6] 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. (CRI) 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.[17] (Note : the recent discoveries off the coast of Brazil should be greater, with proven reserves of 30 billion,[18] and a potential for 50 to 80.[19]) This considerable increase has been made possible by the combined use of horizontal drillinghydraulic fracturing, and a large number of wells drilled. While these technologies have been consistently in use since the 1980s, Bakken 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. CRI developed a technology allowing its rigs to move a few hundred yards on hydraulic “feet”, increasing the rate of well drilling.[20]

[EDIT]OIL PRODUCTION ESTIMATES

Oil wells producing from the Bakken Formation, US and Canada

The greatest Bakken oil production comes from Elm Coulee Oil FieldRichland County, Montana, where production began in 2000 and is expected to ultimately total 270 million barrels (43,000,000 m3). 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.[21]

New interest developed in 2007 when EOG Resources of Houston, Texas reported that a single well it had drilled into an oil-rich layer of shale below Parshall, North Dakota was anticipated to produce 700,000 barrels (110,000 m3) of oil.[22] This, combined with other factors, including an oil-drilling tax break enacted by the state of North Dakota in 2007,[23] shifted attention in the Bakken from Montana to the North Dakota side.[citation needed] The number of wells drilled in the North Dakota Bakken jumped from 300 in 2006[24] to 457 in 2007.[25] Those same sources show oil production in the North Dakota Bakken increasing 229%, from 2.2 million barrels (350,000 m3) in 2006 to 7.4 million barrels (1,180,000 m3) in 2007.

The state Industrial Commission said crude production in September 2011 totaled 464,122 barrels a day, or nearly 123,000 more barrels than September 2010. Ron Ness, president of the North Dakota Petroleum Council, said the state should end 2011 with about 150 million barrels of oil produced.[26] In fact, North Dakota produced 152.985 million barrels in 2011, with a strong increase in the last quarter of the year. In December 2012, the record amount of 23.834 million barrels have been produced in North Dakota. North Dakota Production for 2012 was estimated to reach around 200 million barrels. In fact, 242.447 million barrels were produced, much more than estimated.[27]

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.[28] 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.

[EDIT]EXPLORATION AND PRODUCTION

North Dakota oil production

A number of publicly traded oil and gas companies have drilling rigs in the Bakken region, with varying asset prices, risks and potentials. These include Anglo Canadian Oil Corp.,[29] Concho Resources Inc.,[30] Abraxas Petroleum Corporation,[31]EOG Resources Inc.,[32] Continental Resources Inc.,[33] Whiting Oil & Gas Inc.,[34] Marathon Oil Corporation,[35] QEP Resources,[36] Brigham Exploration[37] (bought by Statoil in 2011), Hess Corporation,[38] Samson Oil and Gas Ltd,[39]Statoil,[40]ConocoPhillips[41] and Exxon Mobil Corp.[42]

[EDIT]EFFECTS OF THE BOOM

The technological changes have caused a tenfold increase in the price of oil leases, which are often made for 3 or 5 year terms. But the leases typically don’t run out if an oil company starts drilling, which results in a huge push to commence drilling on as many as possible before they expire. The resulting sudden boom has reduced unemployment and given the state of North Dakota a billion-dollar budget surplus. But the industrialization and population boom has also put a strain on water supplies, sewage systems, and government services of the small towns and ranches in the area.[43] [44] [45]

[EDIT]SEE ALSO

[EDIT]REFERENCES

  1. ^ Lexicon of Canadian Geological Units. “Bakken Formation”. Retrieved 2009-03-26.
  2. ^ Nordquist, J.W., Mississippian stratigraphy of northern Montana,Billings Geological Society, 4th Annual Field Conference Guidebook, pp. 68–82, 1953
  3. ^ Bakken Formation: Will it fuel Canada’s oil industry?, June 27, 2008, cbc.ca.
  4. ^ US Energy Information Administration, November 2008,Technology-based oil and natural gas plays: Shale shock! Could there be billions in the Bakken?, PDF file, retrieved 16 January 2009.
  5. a b “3 to 4.3 Billion Barrels of Technically Recoverable Oil Assessed in North Dakota and Montana’s Bakken Formation—25 Times More Than 1995 Estimate”. U.S. Geological Survey. April 10, 2008. Archived from the original on 11 April 2008. Retrieved 2008-04-11.
  6. a b c ND study: 167 billion barrels of oil in Bakken
  7. ^ http://www.nd.gov/ndic/ic-press/bakken-form-06.pdf
  8. ^ “New Drilling Method Opens Vast U.S. Oil Fields”. FoxNews.com. 2010-04-07. Retrieved 2011-02-23.
  9. ^ “Producers turn to railroads for shipping Bakken crude”. Tulsa World. 2011-01-28. Retrieved 2011-02-23.
  10. ^ “The Virginia Gazette, Williamsburg Virginia > News > Update on oil”. Vagazette.com. Retrieved 2011-02-23.
  11. ^ Diagenesis and Fracture Development in the Bakken formation, Williston Basin: Implications for Reservoir Quality in the Middle Member, by Janet K. Pitman, Leigh C. Price, and Julie A. LeFever, U.S. Geological Survey Professional Paper 1653, 2001.
  12. ^ Donald Barrs, Devonian System, in Geologic Atlas of the Rocky Mountain Region, Rocky Mountain Association of Geologists, Denver, CO, 1972: p. 98.
  13. ^ Yedlin, Deborah (2008-01-16). “Using horizontal drilling techniques in Canada”The Calgary Herald. Retrieved 2008-01-23.
  14. ^ Price, Leigh. “Origins and Characteristics of the Basin-Centered Continuous Reservoir Unconventional Oil-Resource Base of the Bakken Source System, Williston Basin” (unpublished paper). Retrieved 2013-02-11.
  15. ^ Bakken formation Reserve Estimates, which is a July, 2006 Press Release from the North Dakota Industrial Commissionwhich is part of the North Dakota State Government thus in the Public Domain
  16. ^ State of North Dakota Bakken Formation Reserve Estimates(PDF).
  17. ^ Continental statement: Bakken’s giant scope underappreciated
  18. ^ “Brazil’s Oil Frontier: Sub-salt drilling could net billions of barrels”. Retrieved December 4, 2011.
  19. ^ “Subsalt”. Retrieved December 4, 2011.
  20. ^ Continental Resources, Inc Eco-Pad.
  21. ^ Elm Coulee Field.
  22. ^ 2009 Magnolia Petroleum Current activities (PDF).
  23. ^ Measure offers oil tax rate cut.
  24. ^ 2006 North Dakota Oil Production by Formation (PDF).
  25. ^ 2007 North Dakota Oil Production by Formation (PDF).
  26. ^ Bakken helps North Dakota surpass oil production record [1].
  27. ^ EIA: North Dakota Oil Production Figures
  28. ^ https://www.dmr.nd.gov/oilgas/stats/historicalbakkenoilstats.pdf
  29. ^ “Current Projects”. Archived from the original on 2010-12-18. Retrieved 2013-02-11.
  30. ^ CXO Profile | Concho Resources Inc. Common St Stock – Yahoo! Finance
  31. ^ “Abraxas Petroleum”. Abraxas Petroleum. Archived from the original on 22 February 2011. Retrieved 2011-02-23.
  32. ^ “EOG Resources Inc”. Eogresources.com. Retrieved 2011-02-23.
  33. ^ “Continental Resources Inc”. Contres.com. Archived from the original on 23 February 2011. Retrieved 2011-02-23.
  34. ^ “Whiting Oil & Gas Inc”. Whiting.com. 2009-12-31. Archivedfrom the original on 8 February 2011. Retrieved 2011-02-23.
  35. ^ “Marathon Oil Corporation”. Marathon.com. Archived from the original on 25 February 2011. Retrieved 2011-02-23.
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