Drill Bit Acoustic Calibration for Rock Property Measurement
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Solution Overview
Problem
Current methods for obtaining absolute values of mechanical rock properties during drilling are limited in accuracy and efficiency, particularly in identifying fractures and mechanical boundaries, which hinders effective drilling and completion practices in hydrocarbon reservoirs.
Innovation Solution
A method involving acoustical signals from sensors on a bottom hole assembly, processing forces and displacements to derive scalars that apply to stress-strain relationships, allowing for the determination of absolute mechanical rock properties by interacting with known media like cement and then applying these scalars to unknown rock formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MWD methods are used to obtain mechanical rock properties, then drilling operations can proceed, but the accuracy and reliability of mechanical rock property values are limited
Solution Approach 1:
The system performs preliminary calibration by drilling through a section of cement with known mechanical properties before entering the hydrocarbon bearing formation. This preliminary action establishes baseline measurements and calibration factors that enable accurate determination of mechanical rock properties in the subsequent formation, resolving the accuracy limitation without requiring complex real-time formation analysis
Solution Approach 2:
Cement serves as an intermediary medium with known mechanical properties that bridges the gap between the drilling system and the unknown formation. By measuring bit interactions with the cement first, the system obtains reference data that acts as a mediator to calibrate and interpret subsequent measurements in the hydrocarbon formation, improving measurement accuracy
2Measurement precision
If measurements are taken while drilling cement with known properties, then calibration data can be obtained, but additional time is required before formation measurements
Solution Approach 1:
The calibration process occurs continuously during the drilling operation while penetrating the cement section, rather than as a separate pre-drilling step. Measurements are taken in real-time throughout the cement section, and the calibration is progressively established, allowing seamless transition to formation measurements without interrupting the drilling operation or requiring additional time
Solution Approach 2:
The cement section is deliberately drilled first as a preliminary action to establish calibration before entering the formation. This preliminary drilling through known-properties material prepares the measurement system in advance, ensuring that when the bit enters the hydrocarbon bearing formation, the system is already calibrated and ready for accurate measurements
3Adaptability or versatility
If absolute values of mechanical rock properties are obtained, then hydraulic fracture stimulation can be optimized, but the complexity of data processing increases
Solution Approach 1:
The system automatically performs the calibration and calculation processes without requiring external intervention or complex post-processing. The measurement system self-calibrates using the cement section data and automatically computes the mechanical rock properties of the formation, reducing the need for complex external data processing systems while enabling optimized stimulation treatment design
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 accurate characterization of rock properties and identification of fractures and boundaries in real-time, enhancing drilling efficiency and optimizing hydraulic fracture stimulation treatments.
Implementation Method 1
receiving acoustical signals obtained from one or more sensors positioned on a component of a bottom hole assembly. The acoustical signals, which may also be considered vibrations, are generated from a drill bit interacting with a material, such as cement
Data Source
AI summary
An innovative apparatus and computer implemented methods to obtain values for a set of scalars corresponding to each force and displacement, which may be obtained from acoustical signals captured by sensors of a drill bit while drilling, in a material of known mechanical properties, such as a cement from casing the well, such that the application and use of the scalars in relation to measurements of the mechanics while drilling, such as the acceleration of the bit and motion of the bit captured by sensors such as accelerometers, allow for absolute values of mechanical rock properties to be obtained in rock formations, being drilled through, with otherwise unknown mechanical properties prior to drilling.