OIL & GAS
Impact of Parent Well Depletion on Child Well Fracture Development
At a Glance
The Challenge
- Develop more sophisticated approaches to characterize fracture geometry and behavior
- Identify the impact of parent well depletion on subsequent wells
The Solution
- Cross-well strain measurements with LF-DAS
- Utilize geomechanical inversion to calculate hydraulic fracture width
- Combine quantitative and qualitative metrics for comprehensive fracture geometry analysis
Added Value
- Revealed significant influence of depletion zone on fracture aperture
- Optimize subsequent well placement strategies to drive uniform depletion
- Adjust proppant size based on fracture width estimations
The Challenge
Hydraulic fracturing treatments require advanced monitoring and diagnostic techniques to understand fracture geometry and behavior effectively. The current available techniques have limitations, necessitating the development of more sophisticated approaches.
The primary objective of this study was to develop and demonstrate our advanced quantitative analysis using low-frequency strain data recorded at a cross well instrumented with optical fiber. The Department of Energy sponsored Hydraulic Fracturing Test Site 2 (HFTS 2) research project provides a comprehensive dataset for identifying and testing new monitoring and diagnostic methodologies. A particular interest for this study was characterizing the impact of parent wells and the child well location on hydraulic fracture geometry.
The Solution
This study aimed to utilize Low-frequency Distributed Acoustic Sensing (LF-DAS) for measuring fracture-induced strain perturbations during hydraulic fracturing. Using a novel geomechanical inversion algorithm allowed for quantitative characterization of fracture widths at two monitoring wells from over 100 treatment stages. By combining quantitative and qualitative cross-well strain attributes, the study achieved a comprehensive understanding of far-field fracture geometry.
The Results
Key findings from the comprehensive analysis include:
- Lateral portions of the wells were delineated by two zones: with and without parent well influence
- Decrease in overall fracture width near the parent well depletion zone
- Consistent fracture width trends despite different completion designs
- Quantitative description of poor stage isolation through restimulated fracture widths
These observations were consistent across the various treatment-monitor well parings.
Added Value
Integrating qualitative and quantitative cross-well analysis revealed that the location of the treatment stage relative to the parent well depletion zone significantly influenced fracture growth and geometry. Notably, fractures grow asymmetrically towards the depleted zone, resulting in reduced fracture aperture at the monitor well.
Actionable insights include:
- Optimize future well placement by leveraging biased fracture growth near parent well depletion zones.
- Dynamically optimize proppant size based on fracture width behavior.
- Calibrate reservoir simulation models to accommodate variable fracture width
Additionally, rapid constraints on interstage communication extent were achieved through reactivated fracture width calculations and in-well measurements, aiding to identify mechanisms driving poor stage isolation.
Inverted fracture width results for each treatment stage. The dashed line indicates the approximate location delineating stages with and without parent well depletion impact.
Reactivated fracture widths in stages 8 and 11 are associated with poor stage isolation.
