Bakken Oil Formation
Williston, North Dakota, is renowned for two things:
1. Legendary NBA Coach Phil Jackson grew up there, where he played basketball for Williston High School and led the team to two state titles; and
2. It's ground zero for America's energy renaissance, home of the Bakken oil formation.
Around the time Jackson was in high school, companies were drilling the Bakken for oil. The Bakken was virgin territory, as it was discovered to contain oil just a few years prior, in 1951.
Fast-forward to today: Late last year, North Dakota shattered its oil production record, extracting 750,000 barrels of oil per day. Production has grown so fast, the state now produces more oil than OPEC member Ecuador.
The Bakken Formation is named after North Dakota farmer Henry Bakken, who owned the land where the formation was initially discovered. The formation is huge, spanning some 200,000 miles in Western North Dakota, Eastern Montana, and Southeastern Saskatchewan. (To put that into perspective, the state of Texas is 262,000 square miles in size.)
In 1953, geologist J.W. Nordquist formally described the Bakken as a prolific rock source with oil migration into surrounding rock reservoirs.
Although North Dakota has been producing oil for the past 60 years, the Bakken was never a major source of the state's production, because the tight oil formation proved too technically-challenging and too costly to produce.
But estimates of reserves continued to rise through the decades...
A landmark paper by Dow in 1974 recognized the Bakken Formation as a major source for the oil produced in the Williston Basin and suggested the Bakken was capable of generating 10 billion barrels of oil.
In 1982 a graduate student at the University of North Dakota further sampled and analyzed the Bakken as part of his Master's thesis, calculating the hydrocarbon potential to be about 92 billion barrels. This data was crunched in 1983, and it estimated the Bakken might contain a resource of 132 barrels of oil in North Dakota and Montana.
But the blockbuster came in 1999, when a research paper by USGS Geochemist Leigh Price estimated the total amount of oil contained in the Bakken Shale ranged from 271 billion to 503 billion barrels.
That's an eye-popping number, for sure. But maybe the most important fact about Price's study is that he argued all the oil "cooked" in the Bakken source rock remained there.
In other words, the Bakken was a giant sponge rock that continuously sucked up the oil it produced... and it held a massive amount of oil.
Around the time Price's paper was published, companies were testing various methods of drilling to access the Bakken's hard-to-get oil — namely, horizontal drilling.
The first horizontal well was drilled in the Bakken in 1987. The rest, as they say, is history...
What follows in an excerpt from a report by Julie LeFever explaining the development of horizontal drilling in the Bakken in the late 1980s:
Drilling activity along the "Bakken Fairway" changed greatly after Meridian Oil, Inc. drilled and completed the first horizontal well in the Bakken Formation. The #33-11 MOI, was initially drilled vertically. It was cored, logged, and drill stem tested, all of which indicated that the formation was tight. Meridian then backed up the hole and kicked off at 9,782 ft. Horizontal drilling was attained at 10,737 ft (measured depth) with a resulting radius of 630 ft. The well was completed on September 25, 1987 for 258 BOPD and 299 thousand cubic feet (MCF) of gas.
The well had a horizontal displacement of 2,603 ft and is now producing in the upper Bakken shale that is 8 ft thick. The decline curve for the #33-11 was remarkably stable for the first two years until additional nearby wells came online. The well has produced 357,671 BO and 6,381 barrels of water (BW) through December 2003.
The success of this well set off the previous notable play dealing with the upper Bakken shale. Operators were eager to use horizontal well technology to encounter more fractures and thus produce more Bakken oil. As in any play, there was a learning curve. The #33-11 MOI took 57 days to drill and complete; 27 days to drill the vertical borehole and 12 days to drill the horizontal section at a cost of $2 million. The third set of ten wells drilled by Meridian, further down the learning curve, had an average cost of $1.08 million and took 35 days to drill. By the end of the play, Meridian Oil, Inc. was touting the fact that they could drill and complete a horizontal Bakken well for essentially the same price as the drilling and completion of a vertical well, around $900,000. Successful wells were capable of producing high volumes of oil (IP's in excess of 1900 BOPD).
Here is a follow-up report from the Associated Press in June 1989 on how horizontal drilling had already changed the landscape:
Horizontal drilling an oil recovery method pioneered in Western North Dakota two years ago is helping to spur activity in the state's oil patch.
During the past week, Pacific Enterprises Inc. of Denver was granted 16 permits to drill horizontal wells in the shale-like Bakken formation in McKenzie County.
It is the highest number of drilling permits taken by one company in a single week since 1981, said Jack Wilborn of the oil and gas division of the state Industrial Commission.
More oil companies are expected to adopt horizontal drilling when attempting to recover oil in the Bakken formation, which is found in several oil-producing counties, including McKenzie, Billings, Dunn and Golden Valley, said Wes Norton, also of the oil and gas division.
"It will be interesting to see if they get drilled," Norton said.
About 1 1/2 years ago, Meridian Oil of Billings, Mont., completed the first successful horizontal well in the state in northern Billings County. Through April, that well had produced more than 146,000 barrels of oil.
Meridian Oil has since drilled 10 horizontal holes that produce 30 to 300 barrels a day.
"None of them have been plugged as dry hole," Norton said.
Five of the 15 active rigs in the state are drilling horizontal wells.
To date, Conoco Oil Co. is the only other company to try horizontal drilling. But state officials say interest in the drilling method is increasing rapidly and interest played a key role in the success of the state's spring oil lease auction. The Land Department held its most successful sale in five years this spring, when it leased 65,000 acres of $3.5 million. A year ago, the state only leased 15,000 acres for about $400,000.
In February 1990, Greg Booth of the Grand Forks Herald added:
In Western North Dakota, billions of barrels of oil lie some 10,000 feet underground, held in fractured shale known as the Bakken Fairway or Bakken Formation.
The formation is only about 10 feet thick. The oil lies in vertical planes, separated by 20 to 200 feet of rock that doesn't produce or contain oil.
In conventional, vertical drilling, a well must hit one of these pockets to produce oil. If it misses, drillers are stuck with a dry well or one that doesn't produce enough to warrant leaving it open. In horizontal drilling, the well passes through many fractures, allowing oil otherwise separated, by impenetrable rock to flow into a single pipe. The odds of a dry well are greatly reduced.
Consider this: In vertical drilling, as many as three quarters of the wells drilled in North Dakota are unsuccessful, and that's considered a good rate. On the other hand, of 42 horizontal wells completed since 1987, only two have been dry, according to John Bluemle, assistant state geologist in Bismarck. That's a 95 percent success rate, which he characterizes as "unusually high."
To go from vertical to horizontal, drillers use an angled motor in the well hole, said Bruce Hicks, staff petroleum engineer for the state Geological Survey in Bismarck. The motor is lowered into the vertical hole, and starts drilling at a predetermined angle to reach the oil reserves. When the desired angle is reached, an "angle hold assembly" is put in the hole so the rest of the well can be drilled horizontally along the oil-producing formation.
In a typical North Dakota horizontal well, it takes about 800 feet to go from vertical to horizontal, Hicks said.
In the Bakken Formation, there are two types of fractures, [Julie] LeFever said. Regional fractures are widely spaced. Within the regional fractures are smaller fractures, called microfractures.
Temperature and pressure combine to form oil from the organic material in rock, called "source rock." The resulting liquid occupies more volume, forcing the rock to break up. The high pressure can force oil up to the surface when a well is first drilled, resulting in a flowing well that doesn't require a pump in its initial stages.
Oil companies look for the fractured shale as a sign of a promising well. "The more busted up the rock is, the more oil you're going to get," LeFever said.
The Bakken Formation is capable of forming as much as 92.3 billion barrels of oil, according to a paper written by geologist and UND graduate Rick Webster. Oil produced in the Bakken also can migrate to other rock formations underground. In all, about 10 billion barrels might be recoverable through horizontal and conventional techniques, some geologists estimate.
By the 1990s, most oil companies had given up on trying to coax the oil trapped in tight shale to the surface from the Bakken.
But a stubborn, independent wildcat geologist wouldn't give up...
His name is Dick Findley. And he's known as the father of the Bakken.
Dick Findley is credited with cracking the code for the Bakken in 1996, ultimately leading to the development of the giant Elm Coulee Field (known as "Sleeping Giant" at the time) in the Bakken in Eastern Montana.
Findley's discovery was so epic, he was awarded Explorer of the Year in 2006, some 10 years after his discovery.
You see, a few miles outside Sidney, Montana, Findley uncovered a layer of dolomite, a porous mineral running between two shale layers where oil and gas had previously been found.
His theory was simple: If the dolomite was drilled and fractured in the right direction, it would draw in oil from the shale above and below.
Findley hoped this "two-for-one" approach would make the vast Bakken field economical to produce where other approaches had failed.
But he needed a company with deep pockets and expertise in horizontal fracturing to accomplish this...
Findley got his wish when oil giant Halliburton signed on to test his theory.
In 1998, Halliburton invested in a limited number of drilling programs in the Bakken. Drilling began in early 2000. The first well drilled by Halliburton — christened Burning Tree State — called for a 10,000-foot vertical well with a 3,000-foot horizontal drill well.
The horizontal well only got to 1,200 feet, due to drilling problems.
Nevertheless, they continued with the fracturing...
Oil production instantly exceeded their wildest dreams.
As word spread of Halliburton's success, other companies came rushing into the Bakken.
While all of this was going on, the U.S. Geological Survey (USGS) launched a study to determine how large the oil reserve was, and how it would impact the U.S. oil industry — which, at that time, was experiencing an all-time low.
What they found shocked the USGS and made national headlines for years to come...
The U.S. Energy Information Administration (EIA) made the biggest estimate on what U.S. oil companies could expect to harvest from the Bakken Basin: a whopping 503 billion barrels of oil.
Today, the Bakken is considered one of the largest (possibly the largest) continuous hydrocarbon accumulations in the world.
It's an over-pressurized system, which is why wells drilled have such high initial production rates.
The high pressure in the Bakken suggests the oil is contained within the source rock itself. This means the oil remains in place and is tightly contained throughout the geologic structure.
Typically, highly-pressurized source rocks squeeze oil out into surrounding reservoirs, which also produce surface seeps.
But not the Bakken...
The formation's high pressure — coupled with advances in technology — make each well drilled in the Bakken capable of producing 600,000 and 700,000 barrels of oil over the course of its life.
Bakken production took off in 2008 and was producing around 150,000 barrels per day.
As you read this, North Dakota is pumping 768,000 barrels per day and has over 3,000 wells working.
Do the math: Oil production has increased 412% in just four years.
If that's not a boom, I don't know what is.
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