Optical Pulse Combining for Wellbore Telemetry Signal Loss

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Solution Overview

Problem

Optical pulses used in wellbore telemetry systems experience significant signal intensity loss due to distance and power limitations, posing safety concerns and nonlinearity issues when transmitted through long fiber optic cables.

Innovation Solution

The system employs a method to combine multiple optical pulses with predetermined phase relations into a single combined pulse, utilizing the Talbot effect to maintain signal intensity within safe thresholds, and transmits this combined pulse through a second optical fiber with lower dispersion for effective sensing and data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If optical pulses are transmitted through long fiber optic cables to reach distant downhole regions, then the measurement coverage area is improved, but the signal intensity loss increases

Engineering Contradiction:

Improvemeasurement coverage areaVSAvoidsignal intensity loss

Core Design Contradiction:

Area of stationary objectVSLoss of energy

Solution Approach 1:

Multiple optical pulses are combined through constructive interference to form a single high-intensity pulse at the target location. The system transmits several lower-power pulses that interfere constructively at the downhole region, achieving both long-distance coverage and sufficient signal intensity without exceeding surface power limits.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system transitions from transmitting a single high-power pulse to transmitting multiple lower-power pulses with specific phase relationships. By adding the temporal dimension of pulse sequencing and controlling phase relationships, the system achieves high intensity at the target while keeping individual pulse intensities within safe transmission thresholds.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Power

If higher power optical pulses are transmitted to maintain signal strength over long distances, then the signal intensity is improved, but safety concerns and nonlinearity issues worsen

Engineering Contradiction:

Improvesignal intensityVSAvoidsafety concerns and nonlinearity issues

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The transmission is segmented into multiple separate optical pulses rather than transmitting a single high-power pulse. Each individual pulse remains below the threshold that causes safety concerns and nonlinearity, while their combined effect through constructive interference achieves the required signal intensity at the target location.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the phase parameters of multiple optical pulses to achieve constructive interference at the target location. By precisely controlling the phase relationships between pulses, the system concentrates energy at the downhole region without requiring any single pulse to exceed safe power levels during transmission.

Inventive Principle:

Principle #35Parameter changes

3Power

If multiple optical pulses are combined to increase signal strength, then the power is improved, but the device complexity increases

Engineering Contradiction:

Improvecombined pulse intensityVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The system uses the natural phenomenon of optical interference to combine pulses automatically. The fiber optic cable itself serves as the combining medium through the Talbot effect, eliminating the need for complex external combining hardware. The pulses self-organize through constructive interference based on their phase relationships and the fiber's dispersion properties.

Inventive Principle:

Principle #25Self-service

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 enhances signal strength by amplifying individual pulse intensities, maintaining safety and preventing nonlinearity issues, enabling reliable measurement and data transmission over long distances in wellbore environments.

Implementation Method 1

utilizing the Talbot effect to maintain signal intensity within safe thresholds

Methodology Applied

Scientific EffectTalbot effect:

Implementation Method 2

a first optical fiber having a first dispersion value... wherein the plurality of optical pulses combine into a combined optical pulse

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentUS10072498B2Providing high power optical pulses over long distances

Publication Date: 2018.09.11 HALLIBURTON ENERGY SERVICES INC

AI summary

The disclosed embodiments include a method and fiber optic cable to provide optical pulses for sensing, and an optical telemetry system. In one embodiment, the method includes sequentially transmitting a plurality of optical pulses through a first end of a first optical fiber disposed in a first section of a wellbore. The plurality of optical pulses is combined into a combined optical pulse at a distance from the first end of the first optical fiber. The method further includes transmitting the combined optical pulse through a second optical fiber disposed in a second section of the wellbore, and the second optical fiber includes a second dispersion value, where an absolute value of the first dispersion value is greater than an absolute value of the second dispersion value.