In the eight years since the first commercially successful well in the North Dakota Bakken formation was horizontally drilled and fracture-stimulated, the operator of that well has made steady and continual improvements in its application of drilling and completion techniques.

By capitalizing on these improvements, Continental Resources was the first to complete a 390-m (1,280-ft) lateral multistage frac in 2007, a horizontal well in the Three Forks formation in 2008, and a paired Middle Bakken and Three Forks well in 2010.

The lessons learned and experiences gained from these successes helped the company further tackle the challenges of tapping the Bakken shale in a manner that was both environmentally and economically friendly. In doing so, Continental took an approach different from the rest.

New approach

Where other companies were using a single-pad technique, Continental applied the old adage of doing more with less to its well development strategy. Using the company’s ECO-pad technique, multiple wells can be drilled and completed from a single 8-acre pad. This reduces the well’s surface impact by 65%, according to the company.

The technique allows development of two separate formations (Bakken and Three Forks) on two separate spacing units simultaneously, increasing production efficiency. Thanks to advancements in technology, the technique has evolved since it was first used in 2010 in Dunn County, N.D.

“When we originally began to utilize the process, it was a four-well concept,” said Pat Bent, vice president of Drilling for Continental. “We felt like it was the most displacement in a build section we could do at the time. Since then, technology has improved to the point where we have ECO-pads with four, six, and as many as 14 wells currently in the Bakken.”

The company has seen tremendous results with the technique. For example, its Dvirnak-Pletan ECO-pad project was completed in 4Q 2011 and produced a total of 7,352 gross boe/d for all four wells in the initial one-day test periods, or an average of 1,838 gross boe/d per well, according to a company press release.

Optimized operations

The company uses a batch drilling process to optimize its operations. All four surface holes are drilled first, followed by four intermediate sections, and then finished with the laterals. According to the company, the process saves significant time and costs associated with switching out drillpipe and mud systems for the three different downhole sections.

The true vertical depth of an average Continental well is 2,895 m to 3,200 m (9,500 ft to 10,500 ft). The meas- ured depth for typical 3-km (2-mile) lateral averages 6,096 m to 6,706 m (20,000 ft to 22,200 ft), according to information provided by the company.

One of the more significant operational efficiencies gained by using the ECO-pad is the reduction in time it takes to move the rig. The company uses walking rigs, and it takes approximately eight hours for the rig to walk to the next well. The 2013 target goal for rig moves location to location is five days, Bent said.

“If you drill singles, you add five days to each consecutive well,” he said. “We can walk our rigs wellcenter to wellcenter in a relatively short amount of time, so we’re able to drill back-to-back sections. The efficiencies that we’ve seen have been in the 20% to 30% range. This is partially attributable to the ECO-pad technique and to our rig fleet.”

Consolidating drilling operations for four wells on one ECO-pad has also brought cost savings. In addition to the reduced drilling costs, a reduction in completion costs also is accomplished by conducting fracture stimulation treatments on multiple wells in one continuous operation . Coiled tubing is used for well cleanout to approximately 5,791 m (19,000 ft), Bent said.

All drilling activity is closed-loop, with produced and stimulation flowback water going to storage tanks for transportation to saltwater disposal facilities. Post-completion, about 25% of the disturbed area is reclaimed when the wells go into production.

Future growth

As the leading lease holder with more than 1.1 million net acres in both the North Dakota and Montana Bakken formation, Continental believes the ECO-pad is the key to maximizing development. In a 2011 annual report, the company said it plans to increase the use of the concept as the field matures.

According to Bent, the company’s multiwell pad activity through 2012 included 47 locations, with an additional 71 pads planned for 2013.

“Our year-end goal is to have 70% of our activity on ECO-pad wells,” Bent said. “As acreage comes into production, there are a few locations that we drill that are proved undeveloped. We will be high-grading our rig fleet in 2013, exchanging single rigs for more walkers.”