Downhole Wellbore Coating System for Unstable Shale Stabilization

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Solution Overview

Problem

Drilling through unstable geologic formations such as shale can lead to complications like drill string sticking, wellbore collapse, and shale swelling, which impede drilling progress and require significant delays for fishing and milling operations.

Innovation Solution

A downhole coating system with a retractable application assembly and controller that dispenses a liquid sealant or treatment chemical onto the wellbore wall, using a nozzle and spreader to maintain a uniform thickness and protect the coating from contamination, while hydraulic arms manage shocks and centralize the drill string.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If drilling through unstable geologic formations like shale, then drilling progress can be made, but complications such as drill string sticking, wellbore collapse, and shale swelling occur

Engineering Contradiction:

Improvedrilling progressVSAvoiddrilling stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system applies a liquid coating to the wellbore wall before completing the well, stabilizing the formation in advance to prevent subsequent complications like swelling and collapse. This preliminary stabilization action eliminates the need for fishing and milling operations that would otherwise be required.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A liquid coating acts as an intermediary substance between the drill string and the unstable geologic formation. This coating layer prevents direct interaction that causes sticking and swelling, allowing drilling to proceed through unstable formations without complications.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If fishing and milling operations are performed to address drilling complications, then wellbore stability is restored, but significant time delays occur

Engineering Contradiction:

Improvewellbore stabilityVSAvoiddrilling time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

By applying the liquid coating during the drilling process itself, the system prevents wellbore instability before it occurs, eliminating the need for time-consuming fishing and milling operations that would otherwise be required to restore stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the potentially harmful interaction between drill string and unstable formation into a beneficial stabilized interface by applying the liquid coating. This transforms what would be a problematic situation requiring corrective operations into a controlled, stable drilling environment.

Inventive Principle:

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

3Reliability

If a liquid coating is applied to the wellbore wall, then wellbore stability is improved, but the coating must be protected from contamination

Engineering Contradiction:

Improvewellbore stabilityVSAvoidcoating contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A flexible housing encloses the coating application and curing process, creating a protective barrier that shields the liquid coating from contamination by wellbore fluids and debris. This flexible shell allows the coating to be applied and cured in the harsh downhole environment without compromising its stabilizing properties.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible housing acts as an intermediary protective barrier between the liquid coating and the contaminated wellbore environment. This protective enclosure ensures the coating remains uncontaminated while still allowing it to perform its wellbore stabilization function.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The system stabilizes the wellbore during drilling, reducing the risk of complications and shortening the time required to complete a wellbore by preventing sticking, collapse, and swelling, thereby reducing on-site rig time.

Implementation Method 1

A nozzle is configured to dispense the liquid coating onto a wall of a wellbore

Methodology Applied

Scientific EffectFluid spray: Fluid Spray

Implementation Method 2

A spreader is proximal to the nozzle. The spreader is configured to regulate a thickness of the liquid coating dispensed by the nozzle

Methodology Applied

Scientific EffectMechanical spreading: Brush

Implementation Method 3

The coating housing is configured to seal against a wall of the wellbore and seal the nozzle, spreader, and dispensed liquid coating from contamination within the wellbore

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 4

The wellbore wall is at least partially retained by the cured coating

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS11421507B2Reinforcing wellbores prior to casing and cementing

Publication Date: 2022.08.23 SAUDI ARABIAN OIL CO

AI summary

A coating reservoir defining a chamber operable retain to a liquid coating. A retractable application assembly includes a nozzle fluidically coupled to the coating reservoir. The nozzle is configured to dispense the liquid coating onto a wall of a wellbore. A spreader is proximal to the nozzle. The spreader is configured to regulate a thickness of the liquid coating dispensed by the nozzle. A flexible coating housing is positioned between the coating reservoir and the nozzle. The coating housing is configured to seal against a wall of the wellbore and seal the nozzle, spreader, and dispensed liquid coating from contamination within the wellbore.