Shear Bond Strength Testing Apparatus for Cement
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Solution Overview
Problem
Current methods lack a reliable and reproducible testing protocol to measure the shear bond strength of cement mixes at both the formation interface and casing interface in subterranean reservoirs, which is crucial for optimizing cement performance under in-situ stress conditions.
Innovation Solution
A testing apparatus comprising a circular housing, vertical rod, base plate, and test plates with recessed areas is used to simulate downhole conditions, allowing for the evaluation of shear bond strength between a cement sheath and both the casing and the subterranean formation by applying pressure and measuring the force required to break the bond, thereby determining the shear bond strength at both interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no testing apparatus is used, then cement mixes are evaluated without reliable data, but developing and implementing a testing apparatus increases device complexity
Solution Approach 1:
The patent creates a simplified model system that copies the essential features of downhole conditions. The apparatus uses a mockup assembly with a mockup casing and mockup formation that replicates the critical interfaces (cement-casing and cement-formation) without requiring actual downhole environments, enabling reliable laboratory testing
Solution Approach 2:
The patent introduces a testing apparatus as an intermediary between cement mixes and bond strength evaluation. This apparatus serves as a mediator that translates complex downhole conditions into measurable laboratory parameters through standardized test procedures and mockup assemblies
2Measurement precision
If downhole conditions are simulated in laboratory testing, then accurate bond strength data is obtained, but testing conditions become more complex
Solution Approach 1:
The patent controls and varies specific parameters (temperature, pressure, cement mix composition) independently in the laboratory setting. The apparatus enables precise adjustment of these parameters to simulate downhole conditions while maintaining measurement control, achieving accurate bond strength data through systematic parameter variation
3Strength
If cement mixes are optimized for strength, then zonal isolation improves, but cement brittleness may increase causing cracking
Solution Approach 1:
The patent tests cement mixes under partial downhole conditions (laboratory simulation rather than full in-situ conditions) to identify optimal formulations. By testing shear bond strength at both cement-casing and cement-formation interfaces separately, the apparatus enables optimization of cement properties to achieve sufficient strength while monitoring for brittleness indicators
Solution Approach 2:
The patent performs preliminary laboratory testing of cement mixes before actual downhole application. The testing apparatus evaluates cement bond strength and identifies potential cracking issues in advance, allowing optimization of cement formulations to prevent cracking before the cement is placed in the wellbore
Data Source
AI summary
An apparatus for determining shear bond strength of a cement to be set within a wellbore penetrating a subterranean formation consists of a housing, a vertical rod which extends from the uppermost portion of the housing through the lowermost portion of the housing, a base plate for positioning onto the bottom of the housing and for supporting the lowermost portion of the vertical rod, and a test plate for positioning onto the top of the housing through which the uppermost portion of the vertical rod extends. The apparatus may further contain a push rod. Shear bond strength is determined by introducing into the housing a sample core of the formation prior to introduction of a slurry containing the cement. The force required to break the bond between the vertical rod and the set cement may be used to determine the shear strength between the casing within the wellbore and the set cement when the cement is hardened within the wellbore. The force required to break the bond between the set cement and the sample core may be used to determine the shear strength between the set cement and formation core when the cement is hardened within the wellbore.