Casing Inspection Logging Tool

a technology of logging tool and casing, which is applied in the direction of instruments, survey, borehole/well accessories, etc., can solve the problems of high resolution and achieve the effects of simple construction, greater accuracy, and more rugged design

US20100206064A1Inactive Publication Date: 2010-08-19HUNTING TITAN +1
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2010-08-19
Estimated Expiration
Not applicable · inactive patent

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Abstract

An instrument assembly for a well casing inspection tool, comprising a main shaft having an extension shaft extending therefrom. An instrument head is supported on bearings proximate one end of the main shaft. The rotating instrument head, which includes sensors for measuring wall thickness and caliper of the well casing, provides continuous 360 degree scanning of the interior of the well casing to obtain detailed measurements of the well casing. A motor drives the rotating instrument head through a gear train. A mandrel supported by the main shaft includes exciter coils for wall thickness, caliper, and permeability measurements. A capacitive slip ring couples signals between the rotating instrument head and stationary circuits in the instrument assembly.
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Description

[0001] The present application is related to co-pending U.S. patent application by the same inventor entitled “Capacitive Signal Coupling Apparatus,” filed concurrently herewith.BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention:

[0003] The present invention generally relates to down-hole oil and gas logging instruments and more particularly to logging tools for measuring the inside diameter and wall thickness of the well casing in oil and gas wells and in other applications where these parameters of such pipe must be inspected and measured.

[0004] 2. Background and Description of the Prior Art:

[0005] Well casings and other metallic pipe (“casing”) used in down-hole drilling for oil and gas and, more recently, for geothermal fluids, typically encounters severe conditions of chemical, temperature and pressure phenomena. These conditions subject the casing to corrosion and other types of deterioration from the fluids and other caustic substances that flow through them or which exist...

Examples

Embodiment Construction

[0036]By way of introduction, the present invention is an instrument assembly for a well casing inspection tool. The invention includes sensing coils for making measurements of characteristics of the well casing that are disposed in a rotating portion of the tool to enable continuous 360 degree scanning of the interior of a well casing. By configuring the sensor head to place the sensing coils close to the well casing inner surface and to continuously scan the inner wall of the well casing at relatively high speed, the instrument obtains high resolution data for the entire casing, not just sampled data at regular but spaced apart intervals.

[0037]The instrument for a well casing inspection tool to be described herein comprises an elongated cylindrical body or mandrel that surrounds a stationary main shaft. The longitudinal axis of the main shaft defines the longitudinal axis of the instrument. Extending axially (along the longitudinal axis) from a first end of the main shaft is a sma...