Buried Casing Stub Location via Vector Magnetometry

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Solution Overview

Problem

Locating buried casing stubs is challenging due to interference from other magnetic materials and the inability to determine the depth of the stub using scalar magnetometers, which often results in inaccurate mapping and difficulty in intervention operations.

Innovation Solution

A method utilizing a vector magnetometer to measure and model the magnetic field in a target region, combined with a total station for precise positioning and an accelerometer for inclination determination, allows for the identification and removal of ferrous objects and generation of a model to accurately locate the casing stub, including depth determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a scalar magnetometer is used to map magnetic anomalies in the target region, then the location of magnetic anomalies can be identified, but the depth to the buried casing stub cannot be determined and other magnetic materials cause interference

Engineering Contradiction:

Improvelocation accuracyVSAvoiddepth information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent transitions from using a scalar magnetometer to a vector magnetometer, changing the measurement parameters from single-component magnetic field strength to three-component magnetic field vectors. This parameter change enables depth determination through gravitational gradient measurements and provides directional information to distinguish the casing stub from other magnetic materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a gravitational gradient sensor as an intermediary measurement device that works in conjunction with the vector magnetometer. This intermediary sensor provides additional gravitational field data that helps distinguish the magnetic anomaly source from other ferrous materials and enables depth calculation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a scalar magnetometer is used to map magnetic anomalies, then magnetic perturbation distribution can be visualized, but interference from other magnetic materials such as ferrous debris and well equipment cannot be distinguished

Engineering Contradiction:

Improveanomaly detection reliabilityVSAvoidmagnetic interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes from scalar to vector magnetometer measurements, providing three-component magnetic field data instead of a single magnitude value. This additional directional information allows differentiation between the casing stub anomaly and interference from other magnetic materials through directional analysis and gravitational gradient correlation.

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If records of the well are used to locate the casing stub, then location data may be available, but the records may not include surface location data requiring operator to find the buried casing stub

Engineering Contradiction:

Improvelocation search timeVSAvoidsurface location data

Core Design Contradiction:

Loss of timeVSLoss of information

Solution Approach 1:

The patent replaces manual record searching and physical exploration with an automated vector magnetometer survey system. The system automatically maps the magnetic field, processes the data through gravitational gradient analysis, and generates a hot spot map that directly identifies the casing stub location, eliminating the need for manual record review and physical searching.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach enhances the accuracy of locating buried casing stubs by distinguishing between the casing stub's magnetic anomaly and other ferrous materials, enabling precise intervention operations by providing detailed magnetic field modeling and depth information.

Implementation Method 1

measuring the magnetic field at the survey point with the vector magnetometer

Methodology Applied

Scientific EffectMagnetic field measurement: Magnetometer

Implementation Method 2

an accelerometer, and the method may further comprise determining the inclination of the casing stub locator with the accelerometer

Methodology Applied

Scientific EffectAccelerometer measurement: Accelerometer

Data Source

PatentUS11860329B2Buried wellbore location from surface magnetic measurements

Publication Date: 2024.01.02 SCIENTIFIC DRILLING INTERNATIONAL INC

AI summary

A method for locating a buried casing stub may include a) identifying a target region, b) providing at each of a plurality of survey points in the target region a casing stub locator that includes a vector magnetometer, c) measuring the magnetic field at each of the survey points using the vector magnetometer so as to generate a plurality of magnetic field measurements, d) using the magnetic field measurements to generate a model of the magnetic field of the target region, e) fitting the model generated in step d) to a selected model of a magnetic anomaly created by the casing stub so as to generate model fit information (MFI), and f) locating the casing stub using the MFI. At each survey point, an expected Earth magnetic field can be subtracted from the measured magnetic field. A total station can measure the position and/or the azimuth of the package.