Wellbore Caliper with Buoyancy and Pivot for Ovalized Wells

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Solution Overview

Problem

Existing calipers struggle to accurately measure the largest internal diameter of wellbores, especially when the well logging instrument string is drawn to the bottom of the wellbore by gravity, particularly in highly inclined or horizontal wells where the wellbore becomes ovalized due to drilling and tectonic stresses.

Innovation Solution

A wellbore caliper with a pivotally connected actuator housing and laterally extensible measuring arms, equipped with an adjustable spring to maintain neutrally buoyant status in drilling fluid, allowing the arms to extend and retract to measure the largest diameter, even in non-vertical wellbores, using a linkage system and latch mechanism for precise operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the well logging instrument string is held toward the bottom of the wellbore by gravity, then the instrument can be positioned in the wellbore, but the caliper cannot accurately measure the largest internal diameter in highly inclined or horizontal wells where the wellbore becomes ovalized

Engineering Contradiction:

Improvemeasurement of largest internal diameterVSAvoidperformance in highly inclined or horizontal wells

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies buoyancy as a counteracting force to gravity by designing the caliper with a neutrally buoyant housing that displaces drilling fluid to equal its own weight. This allows the caliper to overcome gravitational pull and float freely within the wellbore, enabling accurate measurement of the largest diameter even in highly inclined or horizontal wells where gravity would otherwise cause the instrument to settle at the bottom.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent employs a movable actuator housing that can pivot relative to the instrument housing, allowing the caliper arms to dynamically adjust their position. This dynamic mechanism enables the measuring arms to extend laterally and seek out the maximum diameter of the wellbore cross-section, adapting to ovalized or irregular wellbore shapes that occur in inclined and horizontal sections.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If a traditional caliper design is used, then the structure is simple, but the caliper cannot float freely to capture the maximum diameter in ovalized wellbores

Engineering Contradiction:

Improvecapture of maximum diameterVSAvoidactuator mechanism with pivot and spring

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The neutrally buoyant housing design counteracts gravitational forces, enabling the caliper to float freely within the wellbore fluid. This buoyancy mechanism allows the instrument to position itself optimally for measurement without being constrained by gravity, capturing the maximum diameter even in ovalized wellbores despite the added complexity of the buoyancy control system.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The actuator mechanism with movable housing and linkage system provides dynamic adjustment capability, allowing the measuring arms to extend and retract as needed to reach the wellbore walls and measure the true maximum diameter. This dynamic design, while more complex than fixed calipers, is necessary to accurately measure ovalized wellbore cross-sections.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the caliper is designed to extend arms laterally to measure diameter, then measurement capability is achieved, but the arms cannot reach the maximum diameter in ovalized wellbores when held by gravity

Engineering Contradiction:

Improvemeasurement of largest diameterVSAvoidarm extension in non-vertical wellbores

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The neutral buoyancy design eliminates gravitational constraint on the caliper arms, allowing them to extend laterally in any orientation without being pulled downward. This enables the arms to reach the wellbore walls and measure the maximum diameter accurately in horizontal or highly inclined sections where gravity would otherwise prevent proper arm positioning.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The movable actuator housing and linkage system provide dynamic control of the measuring arms, enabling them to extend and retract as needed to reach the wellbore circumference. This dynamic mechanism ensures the arms can position themselves to measure the true maximum diameter regardless of wellbore orientation or shape.

Inventive Principle:

Principle #15Dynamics

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 measurement of the largest internal diameter of wellbores, including those that have become ovalized due to drilling and tectonic stresses, by ensuring the caliper can float and move freely within the wellbore to capture the maximum diameter, even in challenging orientations.

Implementation Method 1

an adjustable spring to maintain neutrally buoyant status in drilling fluid, allowing the arms to extend and retract to measure the largest diameter

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentUS9803468B2Wellbore caliper with maximum diameter seeking feature

Publication Date: 2017.10.31 SCHLUMBERGER TECH CORP

AI summary

A wellbore caliper includes an actuator housing pivotally connected at one end to a well logging instrument housing and an actuator disposed in the housing and operable to extend and retract laterally extensible measuring arms.