Drill Bit Acoustic Calibration for Absolute Rock Properties
Find Innovative SolutionsGenerate Solutions
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 optimal drilling and completion practices in hydrocarbon reservoirs.
Innovation Solution
A method involving acoustical signal processing from sensors on a bottom hole assembly to derive scalars from interactions with known rock formations, allowing for the calculation of absolute mechanical rock properties by applying stress-strain relationships to forces and displacements measured during drilling.
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 with basic data, but the accuracy and precision 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 subsequent accurate measurement of formation properties, resolving the contradiction by preparing the system in advance to achieve high precision without requiring inherently more complex equipment.
Solution Approach 2:
Cement with known mechanical properties serves as an intermediary calibration medium between the measurement system and the unknown formation. The cement section acts as a reference standard that mediates the calibration process, allowing the system to translate raw sensor data into accurate mechanical property values for the formation without direct comparison to theoretical models.
2Measurement precision
If detailed mechanical rock property measurements are obtained through calibration with known formations, then accurate characterization is achieved, but the time and cost of drilling operations increase
Solution Approach 1:
The system applies partial calibration action by drilling through a limited section of cement (e.g., 100-500 feet) rather than requiring extensive calibration distances. This partial action provides sufficient calibration data to achieve accurate formation characterization while minimizing the time lost to calibration drilling, balancing measurement precision with operational efficiency.
Solution Approach 2:
The calibration section is drilled preliminarily and intentionally before the main formation evaluation begins. This preliminary calibration action is performed once per well and establishes all necessary calibration factors in advance, preventing the need for repeated calibration measurements that would consume additional drilling time throughout the operation.
3Productivity
If relative changes in rock properties are measured without calibration to known formations, then drilling can proceed quickly, but absolute values of mechanical properties cannot be obtained
Solution Approach 1:
Cement with known mechanical properties serves as an intermediary reference standard that enables the transition from relative to absolute measurements. By comparing formation measurements against this known intermediary, the system recovers absolute mechanical property values without sacrificing drilling efficiency, as the calibration is performed during normal drilling operations rather than requiring separate testing.
Solution Approach 2:
The system changes the reference parameter from unknown formation properties to known cement properties during the calibration section, then reverses this parameter change when measuring the formation. This parameter switching allows the system to operate in absolute measurement mode for formation evaluation while maintaining drilling productivity, as the parameter change occurs automatically during normal drilling progression.
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 precise characterization of rock properties and identification of fractures and boundaries, enhancing drilling efficiency and hydraulic fracture stimulation by providing accurate mechanical property data in real-time.
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
Implementation Method 2
The method involves obtaining scalars by processing the acoustical signals and applying force or acceleration data, and displacement to a stress strain relationship for the material with known rock properties
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.