Enhancing Productivity in Horizontal Wells Through Refracturing

The industry is embracing refracturing as a cost-effective and efficient solution to enhance production in maturing oil and gas basins. As high-quality drilling inventory becomes scarce throughout the Lower 48, the redevelopment of oily basins like the Eagle Ford and Bakken remains a key component in many operators’ drilling plans. The value of refracturing is evident in the growing number of operators running sizable refrac campaigns and the notable acquisitions of under-stimulated acreage throughout South Texas.

As the industry moves toward more advanced refracturing techniques, like “protective refracs,” mechanical isolation has become the optimal method for restimulating entire laterals. The de-risking of modern refrac technology and the continued drop in refrac costs have created an environment for mechanically isolated (mech-iso) refrac activity to double year-on-year, while activity is on track to more than double this year. The following is an overview of the key aspects of refracturing, from benefits to modern best practices and the promising future of refracs.

Understanding Refracturing

Refracturing is the process of re-stimulating a previously fractured well that has experienced a significant decline in production. The first refracturing method was the bullhead refrac (coined the “pump-and-pray” refrac), which aimed to recover additional reserves by pumping water and diverters into an un-isolated wellbore to increase production in understimulated zones.

This early low-cost approach is still used by some operators; however, as modern refracturing techniques have advanced, mech-iso refracs have become the method of choice for operators due to the higher rates of return and predictability. With the mech-iso approach, cemented liners now allow operators to plug and perf the entire lateral for a second time.

Although a higher-cost approach when compared to a bullhead refrac, certain operators have identified significant uplift from new fractures with the use of tracers, when studying the fracture networks in the initial frac and the new fractures in the subsequent refrac.

Key Benefits of Refracturing

1. Increased Productivity: Refracturing boosts the recovery of trapped hydrocarbons, effectively extending the productive life of wells. Today’s advanced mech-iso approach, optimized fracture spacing, and enhanced proppant volumes allow operators to match or even exceed the estimated ultimate recovery (EUR) from the initial stimulation. This is especially valuable in under-stimulated wells with steep decline curves.
2. Environmental Sustainability: Refracturing offers a more sustainable approach by utilizing existing infrastructure, reducing the environmental impact. Compared to new drills, refracs utilize the same well structure and downstream architecture, which reduces site activity and disruption to the surrounding area. With ESG factors becoming central to operational planning, refracturing presents a viable option to minimize impact and lower costs while increasing returns.
3. Profitability: Refracturing complements new drilling. With capital requirements approximately half that of a new drill, refracs provide incremental production in older vintage wells with less financial commitment. Operators can leverage existing land, known geology and infrastructure, adding value in basins where new drilling acreage is limited.
4. Protecting Assets: When stimulated, “protective refracs” are used to protect the production of parent wells from neighboring child (infill) wells on the same pad. By carrying out a protective refrac, a boundary is created around the existing well which limits, or even mitigates, interaction between the child and parent well. This method not only achieves incremental production in existing wells but also allows operators to enhance production and, in turn, profitability in the new drill.

Evaluating Candidates for Refracturing

With the increasing adoption of refracturing, candidate selection has become a critical factor attributed to the success of a refrac campaign.

There is an extensive list of criteria operators consider when evaluating potential candidates: vintage, reservoir maturity, well integrity, rock type, stage spacing, proppant and fluid volumes initially pumped, etc. However, the evaluation used to identify ideal candidates tends to fall under four main considerations:

• Under Stimulated Vintage Wells: Wells typically stimulated between 2008 and 2016 with early-generation completion designs.
• Reservoir Maturity: Vintage wells in well-developed oily reservoirs with a significant decline in production.
• Well Integrity: Previously stimulated wells with limited integrity issues that can withstand the demands of a refrac.
• Initial Proppant Volumes: Vintage wells where initial frac treatments pumped low proppant volumes.

Best Practices in Modern Refracturing

To maximize recovery and minimize risks, operators follow a set of best practices during refracturing operations:

1. Well Clean-Out: A clean-out with a specialized milling assembly clears debris and prepares the wellbore for mechanical isolation, enabling as much as 11,000 ft of 4” liner to be deployed and cemented inside 5-1/2” casing for restimulation of the entire lateral.
2. Mechanical Isolation: Modern cementing techniques typically isolate a previously stimulated well using a 3-1/2” or 4” refrac liner. Refrac liners also reinforce wellbore integrity and facilitate efficient hydraulic fracturing.
3. Zonal Isolation via Plug-and-Perf Operations: Plug-and-perf is a method that isolates individual zones for targeted stimulation. Operators use dissolvable or composite frac plugs to achieve greater reservoir connectivity in the understimulated lateral, capturing additional reserves.
4. Customized Strategies: Every well has a unique architecture, and operators often require a specialized approach when planning the refrac, such as tailored diversion strategies, bespoke completions, and cement blends to optimize returns.

A Case for Refracturing: Success in the Eagle Ford Shale

The Eagle Ford has consistently remained at the center of refracturing advancements and serves as a compelling example of refrac potential.

An Eagle Ford operator significantly increased oil recovery in an understimulated asset by 4.5x the initial EUR using a mechanically isolated refrac. For this operator, as a result of the increased production the projected net present value of the well rose from $2.2m to $8.2m.

Another Eagle Ford operator identified potential refrac candidates by low initial proppant volumes. By increasing volumes 3x during refrac, rates of return increased markedly from 20 bbl/d to 1,500 bbl/d, while rates of decline resembled initial production.

With over 13,000 wells in the Eagle Ford returning approximately 3.5% of reserves, there is great potential for customized solutions to continue to address well-specific challenges and extract stranded reserves. Based on these promising results, many operators are now including refracts as a constant in their drilling plans.

The Future of Refracturing in Oil and Gas

The future for refracturing is bright, with thousands of under-stimulated wells identified in some of the most productive shale plays and recent merger and acquisition activity demonstrating an increasing financial interest.

Designed to extend the life of unconventional shale reservoirs while supplementing basin-wide production, refracturing meets the modern demands of operators, setting the stage for a new era in well-recovery and resource management. With proven benefits in productivity, sustainability and profitability in plays like the Eagle Ford, mechanically isolated refracs are becoming a mainstay in many operators’ drilling plans.

As refracturing technologies and techniques continue to evolve and operators refine candidate selection, refracturing is poised to become a strategic cornerstone for operators when balancing financial goals with environmental considerations.