Acoustic Logging Tool Source Orientation Control

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Solution Overview

Problem

Acoustic logging while drilling faces challenges in maintaining signal quality due to strong drilling noise and anisotropic formation properties, particularly in highly deviated wells, where conventional stacking methods average out important formation information.

Innovation Solution

An acoustic borehole logging tool with independently controlled source elements that modulate their firing signals based on the instantaneous tool face angle, allowing for multi-pole signal generation along different orientations, thereby enhancing signal-to-noise ratio without averaging anisotropic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional stacking methods are used to enhance signal-to-noise ratio, then the signal quality is improved, but the anisotropic formation properties are averaged out and lost

Engineering Contradiction:

Improvesignal qualityVSAvoidanisotropic formation properties

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The acoustic source orientation is dynamically adjusted to maintain a fixed geometric relationship with the tool axis during rotation, allowing the source to sweep through different spatial orientations while preserving the anisotropic signal characteristics for separate processing and stacking

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The logging events are segmented into different stacks based on their tool orientation, with events at similar orientations being stacked together while maintaining separation between different anisotropic signal components, preventing averaging of formation properties

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the tool rotates during logging events, then the measurement coverage is improved, but the signal-to-noise ratio deteriorates due to anisotropic averaging

Engineering Contradiction:

Improvemeasurement coverageVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system dynamically tracks tool orientation and adjusts source firing patterns to maintain consistent geometric relationships, enabling rotation during measurement while preserving signal integrity through orientation-based stacking

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from orientation sensors to control the acoustic source timing and positioning, ensuring that signals are acquired at controlled orientations and properly correlated during stacking to maintain high signal-to-noise ratio

Inventive Principle:

Principle #23Feedback

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 improves the quality of acoustic logging by maintaining signal integrity and capturing anisotropic rock properties without averaging variations, even in deviated wells, by keeping the multi-pole acoustic signal geo-stationary during tool rotation and stacking individual logging events.

Implementation Method 1

The one or a plurality of acoustic sources can be of a multi-pole nature (generally monopole, dipole and quadrupole)

Methodology Applied

Scientific EffectAcoustic wave generation: Sound

Data Source

PatentUS8861307B2Acoustic logging while drilling tool with active control of source orientation

Publication Date: 2014.10.14 SCHLUMBERGER TECH CORP

AI summary

The subject disclosure relates to sonic logging while drilling. A transmitter and at least one receiver are mounted on a drill collar for performing sonic investigations of the formation traversing a borehole.