Threaded Joint Lubricating Coating for Unbalanced Well Loads
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Solution Overview
Problem
Existing lubrication technologies for oil country tubular goods using solid lubricating coating films fail to simulate the large and unbalanced loads experienced in actual well conditions, leading to optimistic evaluations and inadequate lubrication performance, particularly due to the brittleness of binder resins like cellulose and nitrocellulose, and the inability to handle unbalanced loads and structural backlash during make-up and break-out.
Innovation Solution
A solid lubricating coating film is developed using a binder resin comprising alkyd resin and nitrocellulose with melamine cyanurate as the main lubricant, optimized to withstand large and unbalanced loads, with specific particle size and content ratios to ensure effective lubrication and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid lubricating coating film is formed using conventional binder resins (cellulose, nitrocellulose), then the coating provides lubrication, but the binder resin exhibits brittleness and cannot withstand large and unbalanced loads
Solution Approach 1:
The patent changes the chemical composition parameters of the binder resin by incorporating alkyd resin and phenolic resin in specific proportions (alkyd resin: 10-70 wt%, phenolic resin: 5-40 wt%, nitrocellulose: 10-50 wt%). This parameter optimization resolves the contradiction by creating a binder system that simultaneously achieves high strength to withstand loads and maintains lubrication reliability through the combined properties of these resins.
Solution Approach 2:
The patent creates a composite binder resin system combining multiple resin types (alkyd, phenolic, nitrocellulose) rather than using a single resin. This composite approach allows the binder to exhibit both high strength from the alkyd and phenolic resins and reliable lubrication performance from the synergistic combination, resolving the contradiction between strength and lubrication reliability.
2Ease of manufacture
If solid lubricating coating films are evaluated under laboratory conditions, then the evaluation is simple, but the results are optimistic and do not reflect actual well conditions with large and unbalanced loads
Solution Approach 1:
The patent introduces dynamic loading conditions in the evaluation method, applying unbalanced loads that simulate actual well conditions during make-up and break-out operations. This dynamic evaluation approach maintains relative simplicity while significantly improving measurement precision by reflecting real-world operational stresses that static laboratory tests cannot capture.
Solution Approach 2:
The patent applies preliminary unbalanced loads and structural backlash conditions before evaluating lubrication performance. By pre-establishing conditions that mimic actual well operations, the evaluation becomes more accurate without requiring complex equipment, as the preliminary actions prepare the system for realistic performance assessment.
3Stability of the object's composition
If the binder resin contains high proportions of nitrocellulose for film formation, then the coating film forms well, but the brittleness increases and ability to handle unbalanced loads decreases
Solution Approach 1:
The patent optimizes the proportion parameter of nitrocellulose within the range of 10-50 wt% rather than using high proportions. This parameter change, combined with the addition of alkyd and phenolic resins, resolves the contradiction by maintaining sufficient nitrocellulose for good film formation while limiting its brittleness-inducing effects through controlled concentration and synergistic resin combinations.
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 solution provides improved lubricity and corrosion resistance, ensuring reliable lubrication and seizure resistance comparable to conventional grease-like compounds under actual well conditions, addressing the limitations of previous technologies.
Implementation Method 1
a solid lubricant component and a binder resin component, in which the solid lubricant component includes melamine cyanurate... capable of imparting favorable lubricity... to a connection for oil country tubular goods
Implementation Method 2
the binder resin contains an alkyd resin and nitrocellulose... a solid lubricating coating film is formed on a tightening surface
Data Source
AI summary
An agent for forming a solid lubricating coating film on a tightening surface of a thread portion, in which a solid lubricant is dispersed in a binder resin as a matrix component, a main component of the solid lubricant is melamine cyanurate, and an average particle diameter of the melamine cyanurate is 0.1 μm or more and 10.0 μm or less, the binder resin contains an alkyd resin and nitrocellulose, and the alkyd resin and nitrocellulose are contained in an amount of 85 wt % or more of the total binder resin component weight, and a total weight of the solid lubricant is 10 parts by weight or more and 100 parts by weight or less based on 100 parts by weight of a total weight of the binder resin.