Perforation Orientation Optimization for Anisotropic Hydraulic Fracturing
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Solution Overview
Problem
Current methods for determining the optimum perforation orientation and wellbore fluid initiation pressure for hydraulic fracturing in anisotropic formations are inadequate, as they do not account for the directional dependence of rock material properties, leading to suboptimal fracture initiation and increased energy requirements.
Innovation Solution
A method comprising determining anisotropic rock properties, far-field stresses, and borehole stresses to calculate the optimum perforation orientation and initiation pressure, which involves a workflow that includes sonic log data processing, stress tensor rotation, and compliance tensor inversion to identify the ideal perforation angle and pressure for hydraulic fracturing in anisotropic earth formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional perforation orientation methods are used in anisotropic formations, then the perforation process is simpler, but the fracture initiation is suboptimal and energy requirements increase
Solution Approach 1:
The patent applies preliminary action by performing stress tensor rotation and compliance tensor inversion before perforation operations to pre-determine the optimal perforation orientation. This advance calculation identifies the orientation that aligns with minimum principal stress, ensuring optimal fracture initiation conditions are established before the actual perforation process begins, thereby reducing energy requirements during fracturing.
Solution Approach 2:
The patent applies parameter changes by transforming the stress tensor from global coordinates to local borehole coordinates through rotation operations. This coordinate transformation changes the representation of stress parameters to reveal the optimal perforation orientation relative to the borehole geometry, enabling precise alignment with the minimum principal stress direction in anisotropic formations.
2Productivity
If perforations are not optimally oriented, then the perforation process is simpler, but fracture effectiveness decreases and sand production increases
Solution Approach 1:
The patent applies local quality by determining the optimal perforation orientation specifically for each anisotropic formation based on its unique stress tensor and compliance tensor characteristics. Instead of using a universal orientation approach, the method calculates the specific orientation that aligns with the minimum principal stress for each local formation condition, thereby optimizing fracture effectiveness and reducing sand production for that specific location.
Solution Approach 2:
The patent applies feedback by using sonic log data and stress measurements to inform the perforation orientation decision. The process incorporates measured formation properties and stress states to determine the optimal orientation, creating a feedback loop where formation characterization directly guides perforation planning to achieve desired productivity outcomes.
3Measurement precision
If anisotropic rock properties are accounted for, then fracture initiation is optimized, but the calculation complexity increases
Solution Approach 1:
The patent applies segmentation by breaking down the complex problem of determining optimal perforation orientation in anisotropic formations into distinct computational steps: (1) obtaining the stress tensor, (2) rotating the stress tensor to borehole coordinates, (3) obtaining the compliance tensor, (4) inverting the compliance tensor, and (5) calculating the optimal orientation. This segmentation makes the complex calculation process more manageable and systematic while achieving precise initiation pressure determination.
Data Source
AI summary
The subject disclosure relates to determining an optimum orientation for perforations around the circumference of a subsurface borehole and optimum wellbore fluid initiation pressure for hydraulic fracturing in anisotropic formations.