Fracture Driven Interference (FDI): Challenges and Solutions in Focused Restimulation

Fracture Driven Interference (FDI) is a growing concern in the development of unconventional reservoirs, particularly in densely drilled areas. FDI occurs when the hydraulic fracturing of a new well negatively impacts nearby existing wells, leading to production loss, mechanical damage, and other operational issues. In this blog post, we explore the implications of FDI on well performance, specifically focusing on how it affects the potential for future restimulation efforts, and discuss strategies for mitigating its damage through targeted interventions.

Understanding Fracture Driven Interference (FDI)

FDI, commonly known as "frac hit," arises when hydraulic fractures from a newly stimulated well interferes with the existing fracture network or pressure regime of nearby wells. This interference is particularly problematic in mature fields where infill drilling is common, and wells are closely spaced.

Causes of FDI

1. Proximity of Wells

• Close spacing of wells increases the likelihood of FDI, as hydraulic fractures from the new well can easily intersect with the fractures or pressure zones of adjacent wells.

2. Reservoir Pressure Depletion

• Existing wells often exhibit depleted reservoir pressure, which can attract fractures from nearby new wells, exacerbating the interference.

3. Fracture Network Connectivity

• High connectivity within the fracture network increases the risk that new fractures will communicate with those of existing wells, leading to interference.

4. Geomechanical Properties

• The stress regime and rock properties can influence the direction and extent of fracture propagation, increasing the potential for FDI in certain geological settings.

Impact of FDI on Well Performance and Restimulation Potential

FDI can have several detrimental effects on existing wells, which in turn complicates future restimulation efforts:

1. Production Loss

• FDI often leads to a significant drop in production rates in affected wells. This reduction is due to altered pressure regimes, damage to existing fractures, or changes in fluid composition. Wells that have experienced severe FDI may require more intensive restimulation efforts to restore or enhance production levels.

2. Mechanical Damage

• The pressure spikes and mechanical stress associated with FDI can cause damage to the wellbore, such as casing deformation or failure. Such damage not only complicates immediate production but also makes future restimulation more challenging and costly.

3. Alteration of Fracture Networks

• FDI can change the geometry and effectiveness of existing fracture networks. When fractures from a new well intersect and disrupt the network in an existing well, it can result in less efficient hydrocarbon recovery and may necessitate more complex restimulation techniques to restore optimal flow paths.

Mitigation Strategies for FDI and Enhancing Restimulation Success

Given the challenges posed by FDI, operators need to adopt strategies that mitigate its impact and enhance the success of subsequent restimulation efforts:

1. Pressure Management and Monitoring

• Carefully managing reservoir pressure and monitoring it during fracturing operations can help minimize the risk of FDI. For wells already impacted by FDI, pressure management techniques can be applied to stabilize the reservoir before attempting restimulation.

2. Targeted Restimulation Techniques

• Focused restimulation strategies, such as selective perforation or zonal isolation, can be employed to target unaffected or less-damaged zones within a well. This approach allows operators to maximize production without exacerbating existing FDI damage.

3. Wellbore Cleanout Prior to Restimulation

• For wells impacted by FDI, wellbore cleanout operations can remove debris, scale, or other obstructions that may have resulted from interference. A clean wellbore enhances the effectiveness of restimulation by ensuring unobstructed fluid flow and better access to the reservoir.

4. Geomechanical and Fracture Modeling

• Utilizing advanced geomechanical and fracture modeling tools can help predict the behavior of fractures during restimulation. By understanding how fractures will propagate, operators can design restimulation treatments that avoid exacerbating FDI-related damage and instead optimize the reactivation of the existing fracture network.

Case Study: Restimulating FDI-Affected Wells

In a notable example, an operator utilized a combination of wellbore cleanout and focused restimulation to successfully revive a well that had suffered from severe FDI. By first clearing the wellbore of debris and then applying a targeted restimulation technique, the operator was able to restore production rates to near pre-FDI levels, demonstrating the effectiveness of these strategies.

Fracture Driven Interference (FDI) presents a significant challenge in unconventional reservoir development, particularly when planning for future restimulation. However, by understanding the causes and impacts of FDI, and employing targeted strategies to mitigate its effects, operators can enhance the success of restimulation efforts. The combination of pressure management, wellbore cleanout, and advanced modeling techniques provides a pathway to overcoming the challenges posed by FDI, ensuring that wells continue to deliver optimal production throughout their lifecycle.