Targeted Fracture Orientation via Stress Field Modification
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Solution Overview
Problem
Existing methods for hydraulic fracturing in subterranean formations lack control over fracture orientation, often requiring sacrificial wells or natural fractures, which increases costs and complicates the process, especially in heavy oil extraction where wells are not optimally aligned with the in-situ minimum stress.
Innovation Solution
A method that involves drilling and completing two wells, then modifying the stress conditions through pressure and temperature diffusion to create a fracture zone connecting the wells without the need for sacrificial fractures, allowing for controlled orientation of fractures regardless of the initial well orientation relative to the in-situ minimum stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydraulic fracturing is used to create fractures in subterranean formations, then fractures can be formed to increase injectivity and contact area, but the orientation of the fractures cannot be controlled and they follow the plane perpendicular to the least resistance (Smin), which may not align with the desired well connection direction
Solution Approach 1:
The method applies preliminary action by conditioning the stress field in the formation before initiating the targeted fracture. Through pressure diffusion and temperature changes from fluid injection, the in-situ stress is modified in advance to create favorable conditions for fracture propagation in the desired direction connecting two wells, rather than following the conventional perpendicular-to-Smin orientation
Solution Approach 2:
The invention changes physical parameters of the formation by injecting fluids that cause pressure diffusion and temperature changes, thereby modifying the in-situ stress field. This parameter change transforms the stress conditions to enable fracture orientation control, allowing fractures to connect wells even when not perpendicular to the original Smin direction
2Adaptability or versatility
If wells are drilled in directions dictated by deposit channels rather than perpendicular to Smin, then well placement flexibility is improved, but fracture formation to connect the wells becomes difficult or impossible using conventional methods
Solution Approach 1:
By changing the physical parameters of the formation through fluid injection (pressure and temperature), the method modifies the in-situ stress field to enable reliable fracture connection between wells drilled in flexible directions that follow deposit channels, rather than being constrained to perpendicular-to-Smin orientation
Solution Approach 2:
The method applies preliminary anti-action by counteracting the unfavorable stress conditions that would prevent fracture formation between non-optimally oriented wells. Through stress field modification via pressure diffusion and temperature changes, the method creates favorable conditions that overcome the geometric mismatch between well orientation and conventional fracture propagation directions
3Manufacturing precision
If sacrificial wells or natural fractures are used to control fracture orientation, then fracture orientation control is achieved, but the process complexity and costs increase
Solution Approach 1:
The method extracts the need for sacrificial wells or pre-existing natural fractures by directly modifying the stress field in the formation through fluid injection. This eliminates the requirement for additional wells or reliance on natural fractures, simplifying the overall process while maintaining fracture orientation control
Solution Approach 2:
The invention replaces the mechanical approach of using sacrificial wells and natural fracture systems with a field-based approach using pressure diffusion and temperature changes. This substitution eliminates complex mechanical structures and additional wells, achieving fracture orientation control through in-situ stress modification
4Reliability
If steam is circulated through SAGD wells independently for inter-well communication, then communication is eventually established, but the non-productive period takes up to 6 months, wasting steam and capital
Solution Approach 1:
The method applies preliminary action by creating a fracture zone connecting the two SAGD wells before production begins. Through stress field modification via fluid injection, the fracture is formed in advance, enabling immediate inter-well communication and eliminating the 6-month non-productive period required for conventional steam circulation
Solution Approach 2:
The invention skips the lengthy conventional steam circulation process by directly creating a fracture zone that establishes inter-well communication immediately. This rushes through the time-consuming steam circulation phase, allowing production to start much earlier while reducing steam waste and capital tie-up
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables early and uniform communication between wells, reducing the non-productive period in SAGD processes and enhancing petroleum extraction by creating targeted fractures that can be aligned with the well connection, thus improving injectivity and contact area within the reservoir.
Implementation Method 1
modifying the stress conditions through pressure and temperature diffusion to create a fracture zone connecting the wells
Implementation Method 2
modifying the stress conditions through pressure and temperature diffusion to create a fracture zone connecting the wells
Data Source
AI summary
A method is taught of creating one or more targeted fractures in a subterranean formation. The method comprises the steps of drilling and completing two wells in the formation, conditioning said wells to create a stress condition favorable for forming a fracture zone connecting said two wells and initiating and propagating the fracture zone in said formation.