Optical Well Logging Using Distributed Acoustic Sensing

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Solution Overview

Problem

Conventional well logging operations are time-consuming and prone to component failures in hostile wellbore environments, necessitating improvements in efficiency and reliability.

Innovation Solution

A well logging system utilizing an optical waveguide and signal generators to transmit and detect acoustic signals, allowing for the determination of fluid flow rates and characteristics without the need for repeated tool relocation, leveraging distributed acoustic sensing and fiber Bragg gratings to measure acoustic velocities and fluid velocities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional logging tools with electrical and mechanical components are used, then flow rate measurements can be obtained at various locations, but the operations are time-consuming and components are subject to failure in hostile wellbore environments

Engineering Contradiction:

Improvecomponent reliabilityVSAvoidlogging operation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces mechanical flowmeters and electrical components with an optical sensing system using distributed acoustic sensing (DAS) along an optical fiber. The DAS system detects acoustic signals generated by fluid flow at multiple locations simultaneously, eliminating mechanical moving parts and electrical components that are subject to failure in hostile environments. This substitution achieves both improved reliability and reduced measurement time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical fiber serves multiple functions: it acts as both the sensing medium for distributed acoustic sensing and the transmission medium for optical signals. The single optical fiber enables simultaneous measurement of flow rates, fluid characteristics, and acoustic velocities at multiple locations along the wellbore, replacing multiple separate conventional tools with a unified multi-functional system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If conventional flowmeters are positioned at various locations to determine flow rates, then location-specific flow data can be obtained, but the process requires repeated tool relocation which increases time and cost

Engineering Contradiction:

Improvelocation-specific flow data accuracyVSAvoidlogging operation efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent divides the wellbore into multiple measurement segments along the optical fiber length. Each segment can independently detect acoustic signals and determine flow characteristics at its specific location. The distributed nature of the sensing allows simultaneous measurement at numerous locations without requiring physical relocation of the tool, thereby maintaining location-specific measurement precision while dramatically improving operational productivity.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If mechanical spinners are used to measure fluid flow, then flow rate can be determined, but the mechanical components are subject to failure in hostile wellbore environments

Engineering Contradiction:

Improveflow rate measurement accuracyVSAvoidmechanical component durability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces mechanical spinners with an optical acoustic sensing system. The DAS technology detects acoustic waves generated by fluid flow along the optical fiber without any mechanical contact with the flowing fluid. This eliminates mechanical components entirely, achieving both reliable operation in hostile environments and accurate flow rate measurements through acoustic signal analysis.

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 significantly reduces the time and cost of well logging operations by enabling simultaneous measurement of flow rates and fluid characteristics along the wellbore, while also providing insights into fluid composition and pipe compliance, thus enhancing the accuracy and efficiency of well monitoring.

Implementation Method 1

Methodology Applied

Scientific EffectDistributed acoustic sensing:

Implementation Method 2

causing the signal generator to generate at least one signal in the well; and receiving the signal as distributed along the optical waveguide

Methodology Applied

Scientific EffectAcoustic wave propagation: Sound

Implementation Method 3

leveraging distributed acoustic sensing and fiber Bragg gratings to measure acoustic velocities and fluid velocities

Methodology Applied

Scientific EffectFiber Bragg gratings:

Data Source

PatentUS10247840B2Optical well logging

Publication Date: 2019.04.02 HALLIBURTON ENERGY SERVICES INC

AI summary

A method of logging a well can include conveying an optical waveguide and at least one signal generator with a conveyance into the well, causing the signal generator to generate at least one signal in the well, and receiving the signal as distributed along the optical waveguide. A well logging system can include a conveyance with an optical waveguide, and at least one signal generator which is conveyed by the conveyance into a well with the optical waveguide, whereby the signal generator generates at least one signal received with the optical waveguide.