Acoustic Wave Attributes for Cement Bond Detection

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Solution Overview

Problem

In oil and gas well drilling, accurately estimating the amount of cement needed for sealing between the casing and borehole is challenging due to the irregular nature of the borehole, leading to potential gaps in cement bonding, which can compromise the integrity of the well.

Innovation Solution

The method involves using acoustic wave attributes collected during logging while drilling to identify the top of the cement and zones with lacking cement bonds by analyzing changes in casing wave slowness, attenuation, and coherent energy, setting a 'free pipe flag' to indicate these areas, thereby determining the depth of the top of the cement and identifying zones with incomplete bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If acoustic wave attributes are used to detect cement bond quality, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvecement bond detection accuracyVSAvoidacoustic tool complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical measurement systems with acoustic wave-based detection. Instead of using mechanical tools to physically measure cement bond quality, the system uses acoustic waves to penetrate the cement and detect bond integrity through acoustic attribute analysis (slowness, attenuation, coherent energy), thereby simplifying the overall device while improving measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces acoustic waves as an intermediary medium to detect cement bond quality. The acoustic waves serve as a mediator between the measurement tool and the cement bond, allowing non-contact detection of bond integrity through the analysis of wave attributes without requiring direct mechanical interaction with the cement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If real-time acoustic measurement is performed during LWD trip, then productivity is improved, but loss of time for data collection increases

Engineering Contradiction:

Improvecement inspection efficiencyVSAvoiddata collection time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent enables continuous acoustic measurement during the LWD trip through the casing, eliminating interruptions for separate cement bond testing. The acoustic tool operates continuously as part of the normal LWD operation, maintaining productive action throughout the trip while collecting data without requiring additional time for separate inspection operations.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent performs acoustic measurement of cement bond quality during the LWD trip before the trip is completed, allowing preliminary detection of cement bond issues. This enables corrective actions to be taken while still in the well, avoiding the need for time-consuming post-trip investigation and potential re-trips.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If acoustic wave attributes are analyzed to identify voids, then measurement precision is improved, but difficulty of detecting and measuring increases

Engineering Contradiction:

Improvevoid detection accuracyVSAvoidcement void identification complexity

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent detects cement voids by analyzing changes in acoustic wave parameters (slowness, attenuation, coherent energy) as the waves propagate through different cement quality zones. By monitoring parameter variations along the wellbore, the system can identify voids and poor bond zones without complex imaging or interpretation, simplifying the detection process while maintaining high precision.

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 approach allows for real-time detection of cement bond integrity, enabling efficient corrective actions and ensuring proper sealing between the wellbore casing and the surrounding formation, enhancing the accuracy of cement estimation and well stability.

Implementation Method 1

acoustic wave attributes collected from a logging while drilling (LWD) trip through the casing after the casing is set

Methodology Applied

Scientific EffectAcoustic wave propagation: Sound

Implementation Method 2

analyzing changes in casing wave slowness, attenuation, and coherent energy

Methodology Applied

Scientific EffectAcoustic attenuation: Acoustic Absorption

Implementation Method 3

measurements indicative of formation attributes such as compressional slowness (DTc), shear slowness (DTs) and Stoneley slowness (DTst)

Methodology Applied

Scientific EffectSonic slowness measurement: Speed of Sound

Data Source

PatentUS7639563B2Method for sonic indication of voids in casing cement

Publication Date: 2009.12.29 SCHLUMBERGER TECH CORP

AI summary

A method for determining on a real time logging while drilling (LWD) basis the top of cement location between casing transition zones in a borehole using at least one sonic attributes of coherent energy, attenuation and slowness as a function of at least one of depth and time.