Dec. 11 will mark 25 years to the day that Slawson Exploration spud its first horizontal Bakken well, the Sidewinder 1-7H, which was drilled in the upper Bakken shale in the Ash Coulee field in northern Billings County, North Dakota. While a quarter-century ago and just after the fall of the Berlin Wall, the Sidewinder anniversary is noteworthy today for two reasons.
First, Slawson Exploration is the only operator instrumental in the early days of horizontal drilling in the Bakken remaining in the play 25 years later. In fact, Slawson Exploration drilled its first well in the Williston Basin in 1975, putting the company in its 40th year in the basin. But equally noteworthy is the fact that the Sidewinder set an initial production, IP, record at the time. While not the first horizontal well drilled in the Bakken formation - Burlington Resources predecessor Meridian Oil & Gas had drilled what is believed to be the first one two years earlier - at 1,362 barrels, the Sidewinder was the first Bakken well to break the 1,000 barrel IP mark. Today, a 1,300-barrel IP wouldn’t get a lot of attention, but at the time it went on production in February 1990 that IP was big news.
A headline in the Feb. 15, 1990, edition of the Wichita Eagle read “Dakota Oil ‘screams’ at Slawson,” and the next day the Billings Gazette ran a story on the well with the headline “Dakota Oil Strike called major find.” On Feb. 26, 1990, the Oil & Gas Journal’s newsletter said the Sidewinder was “raising eyebrows.” The following May, Western Oil World ran a story on the well under the headline “Slawson drills play’s biggest well.” And in June 1990, company founder Donald Slawson’s sons Todd and Craig, who drilled the well, were featured in the Oil and Gas Investor.
Now, 25 years after spudding the well, brothers Todd and Craig Slawson reflect back on the genesis of the horizontal Bakken play and what led them to drill the Sidewinder and subsequent upper Bakken shale wells over a two-year period, as well as how the team of people involved in drilling and completing the Sidewinder made it the success that it was at a time when horizontal oil well drilling was in its infancy and drilling technology primitive by today’s standards.
Sidewinder genesis
The Williston Basin, along with the entire oil and gas industry, looked much different in 1989. U.S. crude oil imports were approaching record high volumes and West Texas Intermediate had been trading in the $18 to $21 per barrel range throughout the year.
In North Dakota, oil production averaged 7,527 barrels per day in November, the month before the Sidewinder was spud, a stark contrast to the nearly 1.2 million bpd the state is now averaging from more than 11,000 producing wells.
Slawson Exploration also looked a lot different 25 years ago. Following a collapse in the global oil market in the mid 1980s, the firm, once the largest oil producer in Kansas, had sold most of its assets. Todd, a petroleum engineer, and Craig, a geologist, were overseeing company operations in the Rocky Mountain region and had turned their attention to the Williston Basin, while their brother Steve was managing operations in Kansas, Oklahoma and Texas.
“I was 28 then, one year into being the division operations manager after almost all the company was sold to Vintage Petroleum in order for us to stay alive after the price collapses in the middle ’80s,” Todd said.
Craig had been focused on the Powder River Basin, but being a heavy oil play, he said that play “really got cut off at the knees.” After the company laid off several geologists in the slump, Craig had turned his attention to and was helping with Williston Basin operations.
Donald Slawson did not get directly involved in the company’s Rocky Mountain operations but instead left that to Todd and Craig. “He didn’t have a significant role in the resource plays in the Rockies,” Craig said. “He basically gave us free rein to do what we wanted as long as we could find partners.”
Craig said his father, as a Kansas geologist, was much more involved in the Kansas, Oklahoma and Texas operations. “He would come out to quarterly meetings in the Rockies, and as a geologist he would critique your plays and allocate money to them if he thought they were valuable,” Craig said. “If you could find partners, you had leeway.”
So in 1989, the two Slawson brothers set out to find more oil, and in that effort, turned their attention to the Bakken.
Why the upper Bakken shale?
The first horizontal Bakken wells were not drilled into the middle Bakken dolomite in the deep, thermally mature core of the Bakken system (see sidebar on page 13), but instead were drilled in the upper Bakken shale in outlying areas in northern Billings and southern McKenzie counties where the middle Bakken pinches out and where, although hit-or-miss, swarms of clusters could be found where the shale was brittle.
The first, believed to be Meridian Oil and Gas’ MOI Elkhorn 33-11H, was drilled in 1987 in the Elkhorn field which borders the Ash Coulee. That well came in with a 24-hour IP of 258 barrels, not enough to catch much attention but enough to warrant exploration. Between the time Meridian drilled the MOI Elkhorn and Slawson drilled the Sidewinder two years later, numerous horizontal wells were drilled in the upper shale in the area, and while none had IPs near what the Sidewinder produced, the successful wells were those that were hitting swarms of fractures in the upper shale.
“We were not drilling the middle Bakken (dolomite) but rather the Bakken shale itself,” Todd said. “Meridian and Slawson were drilling for fractures in an area known for brittleness, thus the high initial production rates were the result of hitting them.”
Bruce Hicks, who is now the assistant director of the state’s Department of Mineral Resources, was managing the Oil and Gas Division’s new horizontal drilling program in 1989, and he remembers the early horizontal explorers looking for naturally fractured shale. “The huge change back then - they had the horizontal drilling concept down, they knew they could drill horizontally so they were looking for formations that were naturally fractured to take advantage of the long horizontal leg,” Hicks said. “So they looked at that Bakken shale - it was very, very fractured. I remember some of the samples we got were the size of your fist because it would just break apart when they drilled it.”
Craig said he first recognized the potential of the upper Bakken shale in 1988 while studying Mississippian Fryburg carbonate porosity trends that transect the Billings Nose area of northern Billings and southern McKenzie counties. After mapping the various major trends in the area, one particular trend grabbed Craig’s attention because it was not well represented among the production data at the time. That zone lay between the Big Stick and Elkhorn Ranch fields. At that point, he thought the zone was worth testing and began looking for a location.
The Slawson brothers pulled together approximately 11,000 acres in the area and found some partners willing to take on the risk with them. With that, they drilled a vertical well to test the Duperow formation below the Fryburg and the Bakken because it had good production in the area and did not require four-way closure.
That first test well, the vertical Spinnaker Federal 1-18, did not have porosity in the Fryburg or the Duperow formations, but it did have “a decent show” in the upper Bakken shale, according to Craig. He said at that point it was a “simple decision to run pipe” into the upper shale, which the Slawsons did and tested the well on July 16, 1989. “It came on for only 52 bopd and confirmed that vertical wells were a poor method to harvest the Bakken shale,” Craig said.
“After Meridian mastered horizontal wells in the Barnett shale, they came up and drilled an upper Bakken shale well within two miles of the Spinnaker 1-18 with a very decent IP and thus had shown us what we needed to know at exactly the right time,” Craig continued.
“Craig thought we had good acreage,” Todd remembers. “We had a package of acreage we farmed-in to drill Duperow wells from a company called Columbia … and Craig says ‘let’s go try horizontals - Meridian seems to be doing fine with it - let’s go try one.’” And try one they did.
Assembling the team
With a location in mind in the center of the Ash Coulee field about 20 miles northwest of Belfield, the Slawson brothers put together their drilling team.
To navigate through the legalities of the drilling application process, Slawson hired Bismarck attorney Lawrence Bender. Bender had just entered private practice the year before after serving several years as the attorney for North Dakota’s Oil and Gas Division, and Slawson was one of Bender’s first clients.
One of the bigger application issues at the time, Bender remembers, was the size of spacing units. Prior to horizontal drilling, vertical wells were drilled on 160-acre spacing units, but horizontal wells required larger units of 320 and up to 640 acres, depending on lateral length, which the North Dakota Industrial Commission was not used to dealing with. “This was really, really new technology and unique for North Dakota,” Bender said. “So spacing was a huge issue with respect to these horizontal wells.” The Sidewinder was drilled on a 320-acre unit.
To oversee drilling and completion, Todd enlisted mentors Kal Beckman and Leonard Berry.
Todd had been working with both men since first getting involved in the basin five years earlier. “The whole key to this program for Slawson was that I put a lot of trust in Kal Beckman and Leonard Berry and let them just do their job without having to call in for decisions. There were no cell phones at the time anyway,” Todd said. “They got it done. They were drilling the cheapest wells, they were drilling the best wells, and they just got it done.” Both Beckman and Berry remain active in the Williston Basin, Beckman as senior drilling superintendent for XTO Energy and Berry as a consultant for Whiting Petroleum.
Todd recalls Slawson’s completed well costs at the time averaged about $1 million. The Sidewinder ended up costing approximately $1.2 million, but within one to two years, costs of Slawson’s early horizontal Bakken wells were in the $800,000 range.
To help with the engineering, Todd enlisted Dean Brooks, who had recently left Terra Resources. Grace was the drilling contractor with rig 58 run by Mike Reed, whom Todd describes as a “very capable toolpusher” and whose son, Scott, currently runs drilling operations for Nabors Drilling in the Rocky Mountain region after Nabors acquired Grace in 1993.
Eastman-Christenson was hired as the directional company and Teleco was the MWD (measurement while drilling) company. “This was in the days when these companies were totally separate, but now directional companies include MWD services,” Todd said.
Craig served as the chief geologist on the well and Erik Neva was the onsite geologist.
With that team assembled, the Slawson brothers proceeded to drill their first horizontal Bakken well.
Drilling the Sidewinder
For the Sidewinder, it was necessary to build the 90-degree curve perfectly in order to land in the four to five-foot thick upper Bakken shale target. The initial plan was to stop at a kickoff point much higher than necessary in case the angle build assembly built at a lower rate than expected. If built as planned, there would be two tangent sections, one at 45 degrees into the curve and another at 70 degrees to “burn some depth.” The expected build rate was 14 degrees per 100 feet but the kickoff point was designed for 10.2 degrees instead.
During curve building, survey points were received every 30 feet. Whereas computers now do the work, Todd would plot the survey data on a large sheet of graph paper in his office and would continually calculate the actual build angle by hand using sine and cosine functions as drilling proceeded.
On the geology side, Craig said his team had to watch the samples “very carefully” to make sure the bit landed correctly. “As your bit is starting to go at a more deviated angle, you have to have marker beds to actually make small course corrections on the way down to the Bakken,” he said.
When the Sidewinder curve was finished, only one 200-foot tangent at 62 degrees was required. The curve “landed perfectly in the Bakken.”
While the Sidewinder curve was very successful, it was a laborious process. However, after a couple more wells, Todd said, Beckman figured out how to land curves perfectly without having to resort to expensive tangent sections. He said Beckman would simply “flop the build assembly” on its side if it was building too much angle and “exchange azimuth for inclination.” Todd remembers Eastman Christensen personnel at the time telling him that they had never seen a curve landed without a tangent before.
Completing the Sidewinder
The Sidewinder entered the upper Bakken shale at a measured depth of 10,842 feet on the 28th day of drilling. “As soon as we got into the formation we had incredible oil and gas shows,” Todd said. “We probably could have just stopped the well there and had a really big well.” He said because of the high gas concentrations, Beckman’s crew increased the mud weight. But then the drill string became stuck and it “took about nine days to return to drilling.”
On the 42nd day of drilling the well reached a measured depth of 12,656 feet with the lateral extending 1,814 feet into the shale. Todd said the plan was to drill a 2,500-foot lateral, but the gas concentrations were so high, that it was decided to stop drilling and complete the well.
Beckman ran 5.5-inch casing string which consisted of predrilled, three-quarter inch holes every three feet with a soft aluminum plug screwed into each for the portion of the casing in the lateral. No intermediate casing was ever set on the early horizontal wells.
The casing string also had two external casing packers just above the lateral to prevent cement from falling back into the lateral while the vertical hole was being cemented. “We ran two in case one failed to deploy,” Todd said.
Once casing was set, Berry completed the well by going back into the lateral and knocking out the aluminum plugs to put the well on full production. That’s when things got really interesting, especially since the Sidewinder, like all the early horizontal wells, was not fracture stimulated.
After drilling out just 14 feet of plugs in the lateral, the well was producing at such a high rate that Berry had to pull the string and let the well flow. “We left it like that for a while,” he said. “We shut the backside and let it flow up the tubing.” And after 24 hours of that flow the Sidewinder produced 1,362 barrels of oil, 1.1 million cubic feet of gas and no water.
Several months later after the pressure dropped, Berry went back and knocked out the plugs in the remaining 1,800 feet of the lateral. The Sidewinder remained on production through October 1996, and over 1,886 producing days yielded a total of 192,733 barrels of oil for a lifecycle average of 102 bpd.
Slawson’s other early UBS wells
Slawson went on to drill another 18 upper Bakken shale wells in the Ash Coulee and neighboring Bicentennial, Cedar Coulee, Demores, Roosevelt, Rough Rider and Squaw Gap fields in northern Billings, southern McKenzie and northwestern Dunn counties through 1992. Of those 18, one was a dry hole but the other 17 were all successful and nine had IPs over 600 bpd with the highest reaching 1,914 barrels in the first 24 hours. Six of the 19 original wells are still producing.
At 102 bpd, the Sidewinder had the highest daily average of the original 18 successful wells. However, the well with the highest cumulative production is the Silkworm 1-16 in the Squaw Gap field in southern McKenzie County. That well, which is still producing and now operated by XTO Energy, went on production in June 1990 and through August produced a total of 351,379 barrels with a cumulative average of 41 bpd over 8,606 days of production.
Still active, but two companies
Slawson eventually sold all of those early wells to fund other exploration ventures, including gas plays in California, but the company remained active in the Williston Basin whereas many if not most of the companies operating in the basin 25 years ago have come and gone. Now in its 40th year in the basin, Slawson Exploration remains a major player ranking as North Dakota’s 14th largest Bakken oil producer and Montana’s No. 8 Bakken producer.
Donald Slawson passed away in July at the age of 80.
Craig broke away from the family firm in early 2014 to form his own exploration and production company, Slawson Energy.
Todd became president of Slawson Exploration in 2010 and continues in that role as well as overseeing the company’s Rockies operations.
Steve continues to oversee company operations in Kansas, Oklahoma and Texas.
