Drill Bit Sensor System for Real-Time Formation Strength Estimation

Solution Overview

Problem

Current methods for measuring Uniaxial Compressive Strength (UCS) of rock formations are time-consuming and expensive, preventing real-time data analysis and decision-making during drilling operations.

Innovation Solution

A drilling system equipped with a drill bit instrumented with a first sensor to measure cutting forces and a second sensor to measure depth of cut, allowing for the calculation of contact stress against the formation, which serves as an estimate of formation strength similar to UCS.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional laboratory scratch testing is used to measure UCS, then measurement precision is improved, but loss of time and productivity deteriorate

Engineering Contradiction:

ImproveUCS measurement accuracyVSAvoidtime for sample collection and laboratory analysis

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary measurement of formation strength properties directly at the drilling site using sensors on the drill bit, eliminating the need for subsequent laboratory testing. The sensors measure cutting forces and depth of cut in real-time during drilling operations, providing formation strength data before any laboratory analysis would be conducted.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical laboratory scratch testing system with an in-situ sensing system that uses force sensors and depth measurement devices on the drill bit. This substitution transforms the measurement process from a separate laboratory mechanical test to an integrated real-time sensing system during drilling operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If traditional laboratory scratch testing is used to measure UCS, then measurement precision is improved, but productivity deteriorates

Engineering Contradiction:

ImproveUCS measurement accuracyVSAvoidreal-time data analysis capability

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary measurement of formation strength properties directly at the drilling site using sensors on the drill bit, eliminating the need for subsequent laboratory testing. The sensors measure cutting forces and depth of cut in real-time during drilling operations, providing formation strength data before any laboratory analysis would be conducted.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical laboratory scratch testing system with an in-situ sensing system that uses force sensors and depth measurement devices on the drill bit. This substitution transforms the measurement process from a separate laboratory mechanical test to an integrated real-time sensing system during drilling operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If MWD parameters are used to estimate formation strength, then productivity is improved, but measurement precision deteriorates

Engineering Contradiction:

Improvereal-time data availabilityVSAvoidformation strength measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent introduces depth of cut measurement as an intermediary parameter between the directly measurable MWD parameters (cutting forces) and the target formation strength property. By measuring the depth of cut separately and combining it with cutting force data, the system creates a more accurate calculation of contact stress and formation strength than using MWD parameters alone.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the measurement parameters from standard MWD parameters (ROP, WOB, TOB) to include depth of cut measurement. This parameter change enables more accurate calculation of contact stress by providing direct measurement of the engagement depth between the cutting element and formation, rather than relying on empirical correlations.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12305506B1System, method and apparatus for estimating formation strength

Publication Date: 2025.05.20 SCHLUMBERGER TECH CORP

AI summary

Methods and systems are provided that calculate data representing an estimate of formation strength while drilling. The methods and systems employ a drill bit that is instrumented with a first sensor and a second sensor. A processor is configured to i) determine and store first data representing cutting forces acting on a cutting element of the drill bit while drilling based on measurements of the first sensor while drilling, ii) determine and store second data representing depth of cut of the drill bit while drilling based on measurements of the second sensor while drilling, and iii) process the first data and second data to generate and store data representing contact stress against the formation while drilling. This resultant data can be used as an estimate of formation strength. This estimate of formation strength is similar to UCS and can be used in oilfield operations/planning, such as formation characterization while drilling, or drilling efficiency analysis while drilling.