Downhole Rebound Hardness Measurement for Rock Strength Profiling
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Solution Overview
Problem
Current methods for estimating rock strength in wellbore formations require obtaining core samples and retrieving them to the surface for testing, which is time-consuming and expensive.
Innovation Solution
A method and apparatus that convey a tool with a testing surface into the wellbore, propel it to impact the formation at multiple depths, measure hardness from the rebound, and estimate the rock strength profile using these measurements, allowing for real-time in-situ analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If core samples are obtained and retrieved to the surface for testing, then rock strength can be measured, but the process becomes time-consuming and expensive
Solution Approach 1:
The patent replaces the mechanical core sampling and retrieval system with a rebound hardness measurement system that uses a propelled testing surface to impact the formation in-situ. The rebound distance of the testing surface provides hardness data without requiring physical core extraction, thereby eliminating the time-consuming retrieval process while maintaining measurement capability.
Solution Approach 2:
The patent introduces a rebound hardness measurement as an intermediary method between direct rock strength measurement and core sampling. Instead of directly measuring rock strength from core samples, the system uses rebound hardness as a proxy measurement that can be obtained in-situ, reducing the need for time-consuming core retrieval while still providing useful rock strength estimation.
2Measurement precision
If core samples are obtained and retrieved to the surface for testing, then rock strength can be measured, but the cost increases
Solution Approach 1:
The patent replaces the expensive core sampling and laboratory testing system with a more economical in-situ rebound hardness measurement system. By using a propelled testing surface that measures rebound distance, the system eliminates costs associated with core retrieval, transportation, and laboratory analysis while providing sufficient rock strength estimation for drilling operations.
Solution Approach 2:
The patent enables the formation itself to provide the measurement data through the rebound hardness of its in-situ rock surface. The testing surface propels against the formation and the rebound distance directly reflects the rock hardness, allowing the formation to 'self-report' its strength characteristics without requiring external core sampling and laboratory services.
3Productivity
If in-situ rebound hardness measurement is performed, then time and cost are reduced, but the measurement must be performed in the wellbore environment
Solution Approach 1:
The patent designs the tool with a testing surface that can be integrated into existing drilling or wireline operations, allowing the same basic mechanism to serve multiple functions: rock hardness measurement, formation evaluation, and drilling parameter optimization. This multi-functionality reduces the need for specialized complex equipment while maintaining productivity benefits.
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 efficient and cost-effective estimation of rock strength profiles, facilitating improved drilling parameters and reducing the time and expense associated with traditional core sampling methods.
Implementation Method 1
obtaining a measurement of hardness of the formation from a rebound of the testing surface from the formation at the plurality of depths
Data Source
AI summary
A method and apparatus for estimating a rock strength profile of a formation is disclosed. A tool having a testing surface is conveyed into a wellbore in the formation. The testing surface is propelled to impact the formation at a plurality of depths in the wellbore. A measurement of hardness of the formation is obtained from a rebound of the testing surface from the formation at the plurality of depths. The rock strength profile of the formation is estimated using the obtained measurements of hardness at the plurality of depths. A parameter for drilling the wellbore can be affected using the estimated rock strength profile.