Downhole Depth Positioning via Gamma-Ray Correlation

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Solution Overview

Problem

Accurate placement and determination of the location of downhole tools and tubular strings in wellbores are challenging due to the lack of stiffness and rigidity in long tubular strings, leading to improper measurements and placement caused by inconsistencies in component lengths, stretching, and wellbore deviations.

Innovation Solution

A tubular string equipped with a depth measurement module that includes a telemetry device, a wellbore property sensor, and a radiation sensor, which measures wellbore properties and radiation intensity to determine the location based on correlations, using a radioactive source or natural radiation patterns to ensure precise positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the tubular string length is increased to reach deeper wellbore locations, then the coverage depth is improved, but the stiffness and rigidity of the tubular string deteriorates, leading to measurement inaccuracies

Engineering Contradiction:

Improvetubular string lengthVSAvoidstiffness and rigidity

Core Design Contradiction:

Length of stationary objectVSStrength

Solution Approach 1:

The tubular string is divided into multiple discrete components (drill pipes, collars, jars, tool components) whose individual lengths are counted and summed to determine total depth, rather than relying on the continuous stiffness of a single long tubular string

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mechanical measurement system based on tubular string stiffness is replaced with a counting-based system that tracks the number and length of individual components, eliminating the need for the tubular string to maintain mechanical rigidity over long distances

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Length of stationary object

If the tubular string length is increased to reach deeper wellbore locations, then the coverage depth is improved, but the measurement precision deteriorates due to stretching and flexibility

Engineering Contradiction:

Improvetubular string lengthVSAvoiddepth and location measurement accuracy

Core Design Contradiction:

Length of stationary objectVSMeasurement precision

Solution Approach 1:

The lengths of individual tubular components are predetermined and known before deployment, allowing the system to calculate total depth by counting components rather than measuring the actual stretched length during operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of directly measuring the physical position of the tubular string in the wellbore, the system creates a virtual representation of depth by counting and summing the known lengths of individual components, providing an accurate proxy measurement that is independent of physical stretching

Inventive Principle:

Principle #26Copying

3Device complexity

If traditional counting methods are used to determine depth, then the device complexity is low, but the reliability of depth determination deteriorates due to component length inconsistencies

Engineering Contradiction:

Improvemeasurement system complexityVSAvoiddepth determination accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system incorporates feedback mechanisms where the measured wellbore properties and radiation intensity readings are correlated with the counted component lengths to verify and adjust depth determinations, improving reliability without significantly increasing complexity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from relying solely on component length parameters to incorporating additional parameters such as wellbore property measurements and radiation intensity correlations, creating a multi-parameter verification system that enhances reliability

Inventive Principle:

Principle #35Parameter changes

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

This solution enables accurate and precise placement of downhole tools and tubular strings by correlating wellbore properties and radiation intensity, overcoming the limitations of traditional measurement methods and ensuring correct positioning in wellbores.

Implementation Method 1

measuring a correlation between a wellbore property that is a function of depth and a radiation intensity at at least one location within the wellbore

Methodology Applied

Scientific EffectGamma-ray radiation detection: Radiation

Implementation Method 2

measuring a first distance, h1, from a rig floor to a top of the tubular string when the depth measurement module is at a first location in the wellbore above the pip-tag and measuring a wellbore property at the first location, DPstart, using the depth measurement module

Methodology Applied

Scientific EffectWellbore property measurement:

Data Source

PatentUS11761327B2Depth positioning using gamma-ray correlation and downhole parameter differential

Publication Date: 2023.09.19 SCHLUMBERGER TECH CORP

AI summary

Methods, systems, and apparatuses for determining the location or depth in a wellbore of a tubular string or downhole component is provided. One method may include placing a tubular string having a depth measurement module into a wellbore, the wellbore emanating radiation at at least one location along the wellbore and determining the location of the depth measurement module in the wellbore based on a correlation between a wellbore property that is a function of depth and a radiation intensity at at least one location within the wellbore.