Basket-Based Eutectic Alloy Plugs for Downhole Loss Zones

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Solution Overview

Problem

Existing methods for sealing lost circulation in oil or gas wells, such as using lost-circulation materials (LCM) and cement, are inadequate in total loss scenarios, and expandable liners face challenges with irregular well diameters and potential fluid leaks.

Innovation Solution

A downhole plugging assembly using a basket filled with eutectic pellets is deployed, where a heater melts the pellets to form a eutectic plug that seals the well section, utilizing a eutectic alloy that melts at a lower temperature than its components and expands upon solidification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lost-circulation materials or cement are used to plug fractures, then the loss zone can be sealed, but the materials drift away deep into the fractures before solidifying

Engineering Contradiction:

Improvesealing effectivenessVSAvoidmaterial placement precision

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The basket is positioned in advance at the loss zone location to serve as a containment structure. Eutectic pellets are then delivered into the basket, which holds them in place until the heating phase. This preliminary positioning prevents the materials from drifting into fractures before solidification occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The eutectic alloy undergoes a phase change from solid pellets to molten liquid when heated, allowing it to flow and fill the loss zone effectively. The material transitions from a contained solid state in the basket to a fluid state that can penetrate and seal the fracture, then solidifies in place to maintain the seal.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If metal expandable liners are used to seal the loss zone, then the well can be sealed, but the expansion process may fail if cuttings fall behind and fluid continues to leak

Engineering Contradiction:

Improvesealing effectivenessVSAvoidadditional packers required

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The basket and eutectic pellets serve as a disposable plugging system. The basket is positioned, filled with pellets, heated to melt the pellets, and then the molten eutectic alloy solidifies to form a permanent plug. This eliminates the need for complex reusable expandable liners and multiple packers.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The eutectic alloy transitions from solid pellets to molten liquid through heating, enabling it to flow into the loss zone and fill gaps that solid materials cannot reach. After filling the fracture, the material solidifies to form a secure seal, providing reliability without requiring additional sealing components.

Inventive Principle:

Principle #36Phase transitions

3Reliability

If packers are installed to create a tight seal, then fluid flow can be prevented, but the packers may not seal properly due to irregular well diameter

Engineering Contradiction:

Improveseal integrityVSAvoidwell diameter variation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The eutectic alloy changes its physical state from solid to liquid when heated, allowing it to adapt to the irregular well diameter and fracture geometry. The molten material flows to conform to the actual wellbore shape and fill gaps, then solidifies to create a seal that accommodates diameter variations without requiring flexible packers.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The phase change of the eutectic alloy from solid to liquid enables it to become fluid and adapt to the irregular well geometry, filling gaps and conforming to the actual wellbore shape. After solidification, the plug maintains the seal integrity while accommodating variations in well diameter that would prevent rigid packers from sealing properly.

Inventive Principle:

Principle #36Phase transitions

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

Effectively seals well sections, including loss zones, by forming a durable plug that maintains well integrity and allows continued drilling operations.

Implementation Method 1

activating the heater to melt the volume of eutectic pellets and the basket to fill the downhole location with the melted eutectic alloy

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

allowing the melted eutectic alloy to cool to form a eutectic plug plugging the downhole location

Methodology Applied

Scientific EffectSolidification: Freezing

Implementation Method 3

utilizing a eutectic alloy that melts at a lower temperature than its components and expands upon solidification

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20250223878A1Method and apparatus for delivering and setting a eutectic alloy plug to cure loss-of-circulation in drilling applications

Publication Date: 2025.07.10 SAUDI ARABIAN OIL CO

AI summary

A downhole assembly is disclosed that includes a basket having a base, a connection end opposite the base, and a side extending between the base and the connection end. A heater extends centrally through the basket from the base, where the heater has an electrical connection at an end of the heater opposite the base. A volume of eutectic pellets is provided in the basket, and the downhole assembly is used to plug a downhole location by using the heater to melt the eutectic pellets at the downhole location.