Straddle Joint for Damaged Well Casing Reconnection

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Solution Overview

Problem

Oil and gas wells often suffer from collapsed or buckled well casing, which restricts the inner diameter and limits access for tools and operations, hindering completion, stimulation, and production.

Innovation Solution

A process involving milling away the deformed casing or liner to expose the surrounding rock, followed by the use of a straddle joint tool to bridge the gap between the milled ends, thereby restoring the continuous length of tubing without restrictions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If milling tool is used to remove deformed casing or liner, then the restriction is removed and inner diameter is restored, but the casing or liner is divided into separate portions creating a gap

Engineering Contradiction:

Improveinner diameter restorationVSAvoidcontinuity of casing

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

A straddle joint tool serves as an intermediary component that bridges the gap between upper and lower portions of the casing or liner. The straddle joint includes sealing elements that connect to the interior surfaces of both casing portions, effectively mediating the discontinuity created by milling and restoring continuous fluid flow path while maintaining structural integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If straddle joint tool is used to bridge the gap between milled ends, then continuity of casing is restored, but the internal diameter of the straddle joint is less than the original casing or liner

Engineering Contradiction:

Improvecontinuity of casingVSAvoidinternal diameter

Core Design Contradiction:

Stability of the object's compositionVSArea of moving object

Solution Approach 1:

The straddle joint is designed to provide sufficient but not necessarily full restoration of the original internal diameter. The sealing elements make contact with the interior surfaces of the casing portions at specific locations, creating an effective seal that restores continuity while accepting a reduced internal diameter as a trade-off for achieving structural continuity and gap closure

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If cement or settable medium is injected through ports in the straddle joint, then surrounding rock is supported and further collapse is prevented, but the complexity of the operation increases

Engineering Contradiction:

Improvesupport of surrounding rockVSAvoidoperation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The straddle joint is equipped with ports that enable injection of cement or settable medium into the surrounding rock before final setting occurs. This preliminary action stabilizes the rock formation and prevents further collapse during and after the reconnection operation, creating a more reliable long-term solution despite the additional operational steps required

Inventive Principle:

Principle #10Preliminary action

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 solution effectively re-establishes the full or nearly full inner diameter of the well casing, allowing for the passage of tools and enabling various downhole operations, thereby enhancing production and access to lower reservoir sections.

Implementation Method 1

milling away casing or liner in the region of the restriction

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 2

locating the straddle joint tool in the upper and lower portions of casing or liner. In this way the gap between the upper and lower portions of casing or liner is bridged

Methodology Applied

Scientific EffectMechanical connection: Mechanical Fastener

Implementation Method 3

After placement of the straddle joint, cement or other settable medium may be injected outwardly through a port, or normally several ports, in the straddle joint. If the surrounding rock has collapsed, this may help support the rock and reduce the chance of further collapse

Methodology Applied

Scientific EffectCement injection:

Implementation Method 4

the straddle joint may grip the interior surface of the upper and lower portions of casing or liner (for example using slips) and the straddle joint may be placed in axial compression. This may be done to help support the formation, which may have collapsed in the region of the deformed casing or liner

Methodology Applied

Scientific EffectAxial compression: Compression

Data Source

PatentUS12305485B2Well collapse reconnect method

Publication Date: 2025.05.20 CONOCOPHILLIPS CO

AI summary

Damaged casing or liner in a hydrocarbon well, e.g. caused by collapsed formation, is remediated using a unique straddle joint. Damaged liner is milled away and a straddle joint (20) located in the exposed ends of liner (8,9), bridging the gap between them and restoring most of the inner diameter. The straddle joint (20) includes cement ports (25) through which cement may be injected into any cavity (4) in the rock surrounding the straddle joint (20), thereby supporting the rock and helping to prevent further collapse.