Wireline Cable Armor Coating for Borehole Corrosion Protection
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Solution Overview
Problem
Wireline cables with galvanized steel armor wires are prone to corrosion in harsh borehole environments, leading to mechanical damage and reduced flexibility, necessitating frequent cable cutting and reducing their useful life.
Innovation Solution
Applying a viscous liquid composition containing a viscous carrier and an oxygen scavenger, such as an oxidizable salt or organic compound, to the exterior of the cable to inhibit zinc coating corrosion, which is formulated to be shear-thinning and resistant to borehole fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zinc coating is applied to steel armor wires to protect from corrosion, then corrosion resistance is improved, but the zinc coating itself corrodes in harsh borehole environments leading to steel exposure and further corrosion
Solution Approach 1:
The patent applies a grease composition as an intermediary protective layer between the zinc coating and the corrosive borehole environment. This grease contains corrosion inhibitors that actively protect the zinc coating, preventing direct contact with corrosive fluids and extending the protective capability of the zinc layer throughout the cable's service life.
Solution Approach 2:
The patent modifies the chemical composition parameters of the protective coating by incorporating specific corrosion inhibitors (such as sulfonates, carboxylates, and phosphates) into the grease formulation. These chemical parameter changes enable the coating to resist corrosion in harsh borehole environments while maintaining flexibility.
2Productivity
If cable length is increased to reach deeper boreholes, then productivity is improved, but mechanical damage or corrosion requires cutting the cable reducing its useful life
Solution Approach 1:
The patent applies corrosion protection grease to the armor wires before the cable is deployed into the borehole. This preliminary protective action ensures that the entire cable length, regardless of how deep it must extend, is pre-protected against corrosion and mechanical damage from the outset, eliminating the need for premature cutting.
3Reliability
If grease is applied to seal against pressure in production wells, then pressure sealing is improved, but the grease coating does not provide sufficient corrosion protection in harsh borehole environments
Solution Approach 1:
The patent creates a composite protective system by combining grease (for pressure sealing) with corrosion inhibitors (such as sulfonates, carboxylates, and phosphates) to form a multi-functional coating. This composite material simultaneously provides pressure sealing capability and corrosion protection against harsh borehole fluids including drilling muds and produced waters.
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 viscous liquid composition effectively reduces zinc coating corrosion by minimizing direct contact with borehole fluids and scavenging oxygen, thereby extending the cable's lifespan and maintaining flexibility.
Implementation Method 1
a different composition in accordance with the present disclosure will give protection... a viscous liquid composition on the exposed armor wires, wherein the composition comprises a viscous carrier and at least one substance which is an oxygen scavenger
Implementation Method 2
a viscous liquid composition on the exposed armor wires... formulated to be shear-thinning and resistant to borehole fluids
Data Source
AI summary
A wireline cable with zinc-coated steel armor wires exposed at its exterior, is protected from corrosion by fluid, such as drilling fluid, in a wellbore by application of a coating of a viscous liquid composition, which may be a thixotropic grease, onto the exposed armor wires. The viscous liquid composition includes a viscous carrier and at least one substance which is an oxygen scavenger. The cable may also be protected by application of such a coating as it is withdrawn from a wellbore and rewound onto a storage drum.