Drill String Caliper Arms for Wellbore Shape Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wellbore caliper devices, particularly those using acoustic travel time, are ineffective in drilling fluids with entrained gas and require accurate acoustic velocity measurements, highlighting a need for alternative methods to measure wellbore shape and distance from the wellbore wall.
Innovation Solution
A drill string caliper system featuring a mandrel with laterally extensible arms and a biasing device to contact the wellbore wall, coupled with a sensor to generate signals corresponding to the arm's lateral extension, allowing for accurate measurement and communication of wellbore size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic travel time based calipers are used to measure wellbore shape, then measurements can be obtained in typical drilling conditions, but the measurements become ineffective when drilling fluid contains entrained gas and require accurate acoustic velocity measurements
Solution Approach 1:
The patent replaces acoustic measurement methods with a mechanical contact-based measurement system. The caliper uses contact arms that physically touch the wellbore wall, with position sensors detecting the lateral displacement of these arms. This mechanical substitution eliminates dependence on acoustic wave propagation through the drilling fluid, thereby resolving the issue of measurement ineffectiveness when gas is entrained in the drilling fluid.
Solution Approach 2:
The patent introduces contact arms as intermediary mechanical elements that transfer the wellbore wall position information to position sensors. These contact arms serve as mediators between the wellbore environment and the measurement system, allowing direct mechanical contact measurement without relying on acoustic wave transmission through the potentially gas-contaminated drilling fluid.
2Measurement precision
If acoustic calipers require accurate acoustic velocity measurements, then measurement accuracy can be maintained, but the system becomes ineffective when acoustic velocity cannot be accurately determined
Solution Approach 1:
The patent replaces acoustic velocity-dependent measurement methods with a mechanical position sensing system. The contact arms mechanically follow the wellbore wall contour, and position sensors directly measure the lateral displacement of these arms. This eliminates the need for acoustic velocity measurements and their associated accuracy requirements, providing adaptability to all drilling fluid conditions including those with entrained gas.
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 reliable measurement of wellbore size and shape, even in challenging drilling conditions, by translating arm extension into sensor signals for surface communication and recording, overcoming limitations of traditional acoustic calipers.
Implementation Method 1
A biasing device is configured to urge the at least one arm into contact with a wall of a wellbore
Implementation Method 2
A sensor is configured to generate an output signal corresponding to a lateral extent of the at least one arm
Data Source
AI summary
A drill string caliper includes a mandrel configured to be coupled within a drill string. At least one laterally extensible arm is coupled to an exterior of the mandrel. A biasing device is configured to urge the at least one arm into contact with a wall of a wellbore. A sensor is configured to generate an output signal corresponding to a lateral extent of the at least one arm.