Current Characteristics of Bakken Well Completions

As the well count in the Bakken or Three Forks shale formations continues to grow, the strategies deployed to hydraulically fracture each new well have changed when compared to previous approaches.
By North American Shale magazine staff | May 07, 2019

As the well count in the Bakken or Three Forks shale formations continues to grow, the strategies deployed to hydraulically fracture each new well have changed when compared to previous approaches. A combination of factors has helped usher in a new fracture design and strategy used by many of the operators nearly every six months for the past several years. New mechanical downhole technology used to perforate and then plug a portion of the wellbore off allow for more precise puncture placements into the wellbore. Dissolvable material, referred to as a diverter, is being widely used to section off parts of a fracture network for a specified period, all to ensure each section of a wellbore gets its desired attention from perfs or proppant and isn’t compromised when other sections are getting fracked. Downhole analytics and data sets are being captured through fiber optic cable. And, petroleum geologists continue expanding on their ever-evolving understanding of the rock at the micro level. All of these factors are also present during a time when many new wells in the Bakken and Three Forks formation are infill wells placed on an existing pad or next to a parent well previously drilled, fracked and brought onto completion.

The interplay between the parent well and the child, or infill, wells has nudged engineers and completion consultants to factor in the effects of placing and then stimulating a wellbore close to an existing wellbore. Despite the new matrix of factors impacting the overall effectiveness of a typical Bakken frack design, Bakken and Three Forks wells are surpassing previous production expectations by continuing with a focus on fracture optimization.

Optimized Completions Unlock Bakken Value
Continental Resources, one of the largest Bakken producers to date, has reported a noticeable uptick in well production from 2011 to the present. The uptick is based on a combination of well placement and better frack jobs. In early 2018, Continental put three wells into its all-time top five producers list because of optimized completions. Each of the three wells averaged more than 1,500 barrels of oil per day for the first 30 days.

The completion changes by Continental have also produced better returns per well. In 2011, a Continental well drilled and completed at an oil price of $65/b would yield a rate of return (ROR) of roughly 15 percent. By 2018, Continental was reporting a 140 percent difference from 2011. A well drilled and completed at $65/b yields a 140 percent ROR. For Continental and several other major operators, the focus on optimized completions has pushed the boundary of the core of the Bakken. Some operators now consider the core much larger than previously thought when new completion designs are deployed.

Marathon Oil Corp. has expanded its core acreage using area-specific completion designs. A four-well pad in Marathon’s Ajax area located in Dunn County, North Dakota, produced roughly 2,400 barrels of oil equivalent for the first thirty days. “Strong early results in the Ajax mark another important step forward in our ongoing efforts to extend the core of our Bakken acreage position,” said Lee Tillman, president and CEO of Marathon. “Through enhanced area-specific completion designs, and a lot of hard work from our Bakken team, we continue to meaningfully uplift the quality of our inventory.”

Committed To The Next Generation Of Completion Design
No Bakken operator has touted its success with fracture design enhancements in the Williston Basin more than Whiting Petroleum. The operator believes it has always been ahead of the competition with testing and deploying new designs and methods. This year Whiting announced it was now using its Generation 5.0 design approach.

The new approach centers around the idea of optimizing the completions to the well spacing and geology of each individual well. For infill wells the strategy is to concentrate more of the stimulation near the infill wellbore, lower the amount of sand used, place more entry points and use more diverter material. For wells further away from other wellbores, Whiting looks to create a mix of far-reaching fractures and near-wellbore concentration while using more sand, fewer entry points and diverter material to ensure all entry points are connected.

No matter the well, Whiting now builds calibrated models for every area, uses multivariate analysis to understand which completions factors impact production most and then works with service companies to ensure they have the latest technology. The main factors Whiting focuses on with new wells is entry points, frack stages, total fluid, proppant, diverters and lateral length.

Investing In The Frack
In early 2018, shale pioneer Liberty Oilfield Services issued an IPO. The fracture design and pressure pumping experts at Liberty have shown how profitable and important the fracturing segment of shale, the Bakken included, can be.

While Liberty has been providing returns to shareholders, it has also continued investing in its suite of fracture-related products. The company has created a proprietary and trademarked FracTrends database that includes results from more than 60,000 wells along with analysis tools. Another trademarked product Liberty calls Fraconomics, allows clients to use big data to find ways to lower a cost of a barrel of oil. To help customers in close proximity to populated areas, Liberty has created a Quiet Fleet that features technology designed to minimize noise pollution created during pressure pumping operations. And, along with last-mile logistics for proppant-to-well timing, the company has also partnered with CAT to provide predicative maintenance management on equipment at the well site. Liberty’s focus isn’t just on the strategy for proppant placement or the use of diverters. The company now tracks, to the minute, the efficiency and activity of its frack fleets. Doing so helps the company greatly reduce client non performing time.

Next Gen Frack Firms On The Way
In addition to the constant research and roll-out of tooling and proppant by major energy service firms, the evolution of the fracking sector has spawned several new firms designed to meet the needs of the modern market.

Axis Energy Services represents a group of companies working to give operators more options with modern well designs and longer lateral lengths. “For too long, E&P companies in the U.S. have had two choices for completions. They could use coiled tubing with reliability issues in longer laterals, or stick pipe requiring too many companies on site—often without the right equipment or crews,” said Wendell Brooks, CEO. “The mission of Axis is simple: to offer our customers a third option to reach new levels of efficiency.”

John Schmitz, executive chairman for Axis, has also discussed the changing face of shale. “As the shale revolution enters the phase of capital efficiency and manufacturing growth, operators can’t afford to have legacy business plans and equipment slow them down or eat into their returns,” Schmitz said. “We formed Axis based on listening to our customers on the new business model and new equipment needed to get wells to production optimally and quickly.”

Lime Rock Partners, a group linked to several shale plays including the Bakken, was an investor in Axis. The company uses data to determine drill-out times prior to starting the process and has new workover rigs and completion specialists focused on optimizing completions for long-lateral shale wells.

To reduce the always-present challenge of frack hits between parent wells and infill wells, Reveal Energy Services has created a new product called FracEye. The system allows operators to make timely adjustments to wells being fracked on multiwell pads that feature parent and child wells. The system categorizes the type and severity of interwell communication by measuring the pressure response from a parent well as hydraulic fracturing proceeds normally in child wells. Geoscientists and completion engineers can use the data to determine if, or to what severity, a frack hit is taking place. The system looks for direct fluid transport from wellbore to wellbore, fluid migration increases, instantaneous pressure response in an offset well or, hopefully, if there is no signal of pressure change in a neighboring well.

Austin, Texas-based Seismos received $10.5 million from investors to harness a software-based technology to also better understand frack hits. Through its product Seismos-Frac, engineers can adjust treatment solutions on the fly. The technology was developed in conjunction with Stanford University faculty.

National Lab Frack Attention
At the national level, several research institutions from the University of North Dakota’s Energy and Environmental Research Center to Oak Ridge National Lab continue to assess, test and research novel or intricate methods to better understand the future of fracking.

Oak Ridge researchers are using a combination of neutron and x-ray scattering to make fracking more efficient. The team is testing the possibility and effectiveness of introducing ultrasonic (acoustic energy) to the downhole rock prior to fracking to increase porosity and permeability once the stimulation takes place.

“It's all about supplying energy into the formation to release hydrocarbons,” explained ORNL researcher Joanna McFarlane.

“Think of a sponge filled with water,” Richard Hale, another ORNL researcher added. “The water doesn’t come out of the pores until you squeeze it. Acoustic energy is really, really good at squeezing these pores. In small core sample–size experiments placed in acoustic baths, we can see the oil flows easily and rapidly from the rock.”

Ultrasonic techniques have previously been used to clear debris near the surface of a well. ORNL researchers believe the same technique might be applicable 8,000 feet below the surface.

A team of researchers at Los Alamos National Lab believe shale stimulation will benefit from understanding previous tectonic movements and water seepage forces not previously considered. A mathematical model shows how branches form off vertical cracks along the wellbore during the fracking process. Further research, they believe, will help engineers better understand how to optimize fracture pumping rates and the viscosity of the fluids pumped.

~From The Bakken Report 2019 print issue