LWD Stoneley-Wave Permeability Estimation with Stabilizers

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Solution Overview

Problem

Existing methods for determining formation permeability, such as shut-in and build-up methods and wireline acoustic measurements, are time-consuming and susceptible to borehole mud invasion during drilling operations.

Innovation Solution

An acoustic logging while drilling (LWD) apparatus that generates Stoneley waves in the annulus between the logging tool and the borehole wall, using a processor to estimate permeability based on formation compressional wave velocity, shear wave velocity, and density, with stabilizers maintaining the tool's centralized position and an acoustic isolator to attenuate tool-borne noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If shut-in and build-up methods are used to determine permeability, then measurement accuracy is improved, but measurement time is excessively long and well shutdown is required

Engineering Contradiction:

Improvepermeability measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces mechanical pressure measurement systems with acoustic wave-based measurement systems. Acoustic waves propagate through the formation and their characteristics (velocity, attenuation) are used to determine permeability, eliminating the need for time-consuming pressure buildup measurements and well shutdown procedures.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses acoustic waves (a form of mechanical energy propagation through fluid-saturated porous media) to indirectly measure permeability. The acoustic wave properties change in response to formation permeability, providing a non-intrusive measurement method that does not require fluid injection or pressure buildup.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Productivity

If wireline acoustic measurements are used to estimate permeability, then measurement time is reduced, but borehole mud invasion affects measurement reliability

Engineering Contradiction:

Improvemeasurement speedVSAvoidpermeability estimation accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent performs acoustic measurements while drilling is still in progress, before borehole mud has time to significantly invade the formation. This timing advantage allows the system to capture formation properties at or near the original wellbore wall, avoiding the contamination issues that affect wireline measurements taken after drilling completion.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The LWD system uses the drilling operation itself to create the measurement conditions. The acoustic measurements are integrated into the drilling process, using the existing borehole environment and formation exposure to obtain permeability data without requiring separate measurement operations that would allow mud invasion to occur.

Inventive Principle:

Principle #25Self-service

3Productivity

If LWD acoustic measurements are performed during drilling, then real-time permeability estimation is achieved and mud invasion impact is reduced, but tool position stability and noise attenuation become critical challenges

Engineering Contradiction:

Improvereal-time measurement capabilityVSAvoidtool stabilization and noise attenuation requirements

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent introduces stabilizers as intermediary components between the LWD tool and the borehole wall. These stabilizers maintain consistent tool position and spacing from the formation, ensuring reliable acoustic coupling and measurement repeatability despite the dynamic drilling environment.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent acknowledges that drilling operations generate significant noise and vibration, but converts this challenge into an opportunity by using surface-based noise filtering techniques and acoustic signal processing to isolate the formation acoustic signals from the drilling noise, thereby extracting useful permeability information even in the noisy drilling environment.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Enables real-time estimation of formation permeability during drilling, reducing the impact of mud invasion and enhancing sensitivity to permeability changes, with improved accuracy and reduced measurement time.

Implementation Method 1

an acoustic transmitter on the logging tool configured to generate a Stoneley wave in an annulus between the logging tool and a wall of the borehole

Methodology Applied

Scientific EffectStoneley wave generation: Acoustics

Data Source

PatentUS7970544B2Method and apparatus for characterizing and estimating permeability using LWD Stoneley-wave data

Publication Date: 2011.06.28 BAKER HUGHES CO

AI summary

Stoneley-wave data acquired in the LWD environment are used to characterize/estimate formation permeability. Real-time Stoneley-wave time-delay/slowness and center-frequency/attenuation data are used to indicate/characterize formation permeability even during drilling. The use of stabilizers mounted at the tool ends helps maintain the tool position from severe decentralization, reducing ambiguities in the permeability characterization/estimation.