Why Liberty is Back in the Bakken

An industry-leading completion design has Liberty set to shine again. Leen Weijers, vice president of technology and sales, details the merits of a slickwater, plug and perf, ceramic-proppant-based completion design.
By Luke Geiver | March 19, 2014

Following Liberty Resources II LLC’s re-entry into the Williston Basin through a $455 million oil and gas asset acquisition earlier this year, the stage is again set for the Denver-based exploration and production company to shine. Before Liberty sold its assets to Kodiak Oil & Gas last year for $680 million, the team was recognized for its unique, industry-leading well recovery rates. After selling its Williston Basin assets, energy investment firm Riverstone Holdings LLC committed $350 million to Liberty to redeploy its talents in other shale plays. Based on the success of its work in the Williston Basin, Liberty chose to return to the Bakken.

In October 2013, Liberty released a Society of Petroleum Engineers paper explaining its completion strategies titled, “The Value Proposition for Applying Advanced Completion and Stimulation Designs to the Bakken Central Basin.” The paper described the variety of completion methods used in the Bakken. “As a consequence, it is not uncommon for different operators to have over a $2 million difference in their authorizations for expenditures, solely because of the differences in approach to the well’s completion and stimulation design.”

The Liberty SPE paper described the company’s method as one “designed to maximize reservoir contact area and optimize the conductivity.” The methodology can result in roughly $1 million to $2 million in additional costs, but the choice can result in greater production during the well’s first year on production, and, the additional costs are paid for through higher IP rates in just a few months.

During a two-year period, Liberty had drilled and completed 29 wells in the Bakken and Three Forks formations before selling its assets, some of which recorded the highest initial production rates of any wells in the play. With 53,000 net acres spread throughout the North Dakota counties of Williams, McKenzie, Divide and Burke, Liberty will once again have the chance to prove that a completion design focus on conductivity and contact area can result in great wells.

The Two C’s Design Approach
The completion design methodology championed by Liberty is actually more similar to a three-legged stool. First, the team emphasizes the importance of stimulating the wellbore using plug and perf. The process creates distinctly distributed initiation points along each stage section of the lateral. “The idea is to create as much surface area as you can,” says Leen Weijers, vice president of technology and sales for Liberty’s Oilfield Services division. Second, the team uses slickwater-based fluids in order to maximize the contact area the fluid touches. Using slickwater also has low matrix permeability damage. The slickwater fluid—a thin viscosity fluid—allows more fractures to be opened during pumping that might not have opened under the normal pumping stress rates applicable to other fluids. “Using a thin viscosity system creates a fracture system that advances the fracture network not only in length direction, but also in the direction perpendicular to the main fracture,” Weijers says. Liberty has proven the benefits of five offset wells in the roughrider area near Williston, N.D., he says. “If you have a fluid with very good proppant transport capability, you are better able to prop that entire fracture open.”

The combination of plug and perf with slickwater fluids creates a more complex fracture network that in return calls for a more complex proppant mixture to maintain the fracture network’s conductivity. Liberty uses smaller proppant in the size of 40/70 to prop deep into the complex network. Then, it uses a moderate 30/50 proppant to provide enhanced conductivity near the wellbore. And, the team also emphasizes the use of ceramic proppants that can provide extra strength to keep partial proppant monolayers and proppant bridging at pinch points sufficiently conductive.

To prove the benefits of the two C’s design methodology, Weijers compares a number of wells completed by various operators in the Rough Rider area. Some of the wells were completed using cross-linked gels, sliding sleeves and a combination of frack sand or ceramic proppants. Another group of wells was completed using a hybrid fluid design with plug and perf with both frack sand and ceramic proppants. And, the Liberty wells in the area were all completed using slickwater fluids, plug and perf and ceramic proppants.

On a 180-day oil production comparison, Liberty’s completion design was superior, yielding almost 85,000 barrels of oil. In second place was the hybrid design at nearly 51,000 barrels of oil, and in third was the cross-linked gel approach at 31,000 barrels of oil. “One of the shortcomings of that analysis is really that I’m just comparing one completion parameter to an overall production response in 180 days of production,” Weijers says. “What you really have to do is determine which parameters are dependent on each other.”

To provide a more comprehensive analysis of the Liberty well completion approach to other’s in the same area, Weijers compiled data sets from the North Dakota Industrial Commission’s Oil and Gas Division and the Geologic Survey. “We looked at a variety of different geologic parameters and completion parameters,” he says. “In general, we would see from the analysis that water cut was a very good proxy for overall reservoir quality.”

In most cases, the wells from the Rough Rider area were completed by different operators using different methodology. “You would think that based on production performance, if reservoirs mattered a whole lot, that some of the best wells would be in the best type of reservoir, but you can see that that is actually not the case,” he said after compiling reservoir data to go along with well production results. “The best producing wells are not driven by the reservoir, they are driven by the completion design.”

Weijers belives that his comparative analysis of wells in the Rough Rider area shows that applying the right completion techniques can more than double the value of an asset, and, that although completion jobs that create larger reservoir contact areas and higher conductivity are more costly, they will increase profitability even more in the Bakken. In the Three Forks, Weijers is analyzing the results of Liberty’s frack designs. Although testing is inconclusive at this point, he believes the same approach will again yield higher production values when compared to other methods.

Weijers and the entire Liberty team will have the opportunity to prove its completion designs through the company’s re-entry into the play. The acreage purchased by Liberty is outside of the operation region in which the company previously worked.

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Author: Luke Geiver
Managing Editor, The Bakken magazine
lgeiver@bbiinternational.com
701-738-4944