Subterranean Formation Breakdown Pressure Calculation
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Solution Overview
Problem
Conventional hydraulic fracturing simulators fail to accurately predict the breakdown pressure of subterranean formations, especially in deviated, cased wells with clustered perforations, due to model simplifications and neglect of factors like well deviation, casing, and cement interactions.
Innovation Solution
A computational framework that transforms in-situ stresses through various coordinate systems to determine hoop stresses at the wellbore-perforation interface, using rotation matrices and accounting for casing-cement mechanical properties and perforation phase angles, to calculate the breakdown pressure based on these stresses and the tensile strength of the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional hydraulic fracturing simulators are used, then the device complexity is reduced, but the measurement precision of breakdown pressure is insufficient
Solution Approach 1:
The computational framework segments the stress analysis into distinct coordinate system transformations: global coordinate system to wellbore coordinate system, then to perforation coordinate system. Each transformation handles specific geometric relationships separately, improving precision while managing complexity through modular computation steps.
Solution Approach 2:
The framework transitions from simplified 2D plane stress assumptions to 3D stress tensor analysis by incorporating wellbore deviation angles and perforation phase angles. This dimensional expansion captures the true complexity of deviated wellbores with clustered perforations, significantly improving breakdown pressure prediction accuracy.
2Reliability
If model simplifications are used in hydraulic fracturing simulators, then the ease of operation is improved, but the reliability of breakdown pressure prediction deteriorates
Solution Approach 1:
The framework incorporates additional critical parameters including wellbore deviation angle, perforation phase angle, and casing-cement mechanical properties. By systematically integrating these parameters into the stress transformation equations, the model achieves reliable predictions for complex deviated wellbores while maintaining a structured computational approach.
Solution Approach 2:
The computational framework acts as an intermediary between simplified simulator models and complex real-world conditions. It transforms in-situ stresses through coordinated rotation matrices that account for wellbore geometry and perforation configuration, bridging the gap between operational simplicity and predictive reliability.
3Measurement precision
If factors like well deviation, casing, and cement interactions are neglected, then the device complexity is reduced, but the measurement precision of breakdown pressure deteriorates
Solution Approach 1:
The model segments the complex interaction system into distinct components: wellbore geometry (deviation angle), casing properties, cement sheath characteristics, and perforation configuration. Each component is analyzed through specific coordinate transformations and stress calculations, enabling precise breakdown pressure estimation while managing computational complexity through systematic decomposition.
Solution Approach 2:
The framework treats the wellbore system as a composite structure involving multiple materials and interfaces: steel casing, cement sheath, and formation rock. By applying transformation matrices that account for the mechanical properties and geometric relationships of each component, the model accurately captures stress distribution at the wellbore-perforation interface.
Data Source
AI summary
Techniques for determining a breakdown pressure of a subterranean formation include identifying in-situ stresses for a portion of a wellbore formed into a subterranean formation; transforming the in-situ stresses (and induced stresses) from a global coordinate system to a wellbore coordinate system of a deviated portion of the wellbore that includes at least one perforation tunnel for a hydraulic fracturing treatment; transforming the in-situ stresses from the wellbore coordinate system to a perforation coordinate system through at least one rotation matrix; determining one or more stresses at a wellbore-perforation interface of the perforation tunnel from the in-situ stresses in the perforation coordinate system; calculating one or more hoop stresses at a perforation tunnel wall of the perforation tunnel from the determined stresses on the wellbore-perforation interface; and determining a breakdown pressure for the subterranean formation based on the calculated one or more hoop stresses and an effect of casing-cement-formation interaction.