Threaded Coupling Design for Drilling Casing Integrity
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Solution Overview
Problem
Current threaded couplings for drilling-with-casing and oilfield operations require costly premium materials and lack efficient methods for accurate positioning and maintaining connection integrity under high torque and pressure conditions.
Innovation Solution
The design includes male and female components with straight threads, negative-angled shoulders, and tapered surfaces to facilitate precise positioning and metal-to-metal sealing, along with bearing journals to prevent disengagement and bending, using standard API stock materials and minimizing material removal for increased strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If premium materials and thicker wall components are used to achieve robust sealing under high torque, then sealing reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the geometric parameters of the thread profile by incorporating a taper angle (1-5 degrees) and optimized flank angles to create a self-sealing mechanism. This allows standard materials to achieve premium-level sealing performance through geometric optimization rather than material thickness increase.
Solution Approach 2:
The invention combines multiple sealing mechanisms within a single coupling design, including metal-to-metal sealing surfaces, tapered threads for alignment and sealing, and optional seal elements. This composite approach to sealing achieves robust performance without requiring expensive thick-walled components throughout the entire assembly.
2Reliability
If tapered threads are used to improve sealing, then sealing performance is improved, but material removal increases reducing structural strength
Solution Approach 1:
The patent optimizes the taper angle to a specific range (1-5 degrees) that provides effective sealing while minimizing material removal. The optimized flank angles and thread depth are calculated to achieve the required sealing performance with the least amount of material removal, preserving structural strength.
3Reliability
If multiple seals are added to achieve fluid-tight connection, then sealing reliability is improved, but connection complexity increases
Solution Approach 1:
The patent merges multiple sealing functions into the thread structure itself through the tapered profile and optimized geometry. The taper angle and flank angles are designed to create sealing contact between the male and female threads during tightening, eliminating the need for separate seal elements and reducing overall connection complexity.
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 configuration enables cost-effective, fluid-tight connections with enhanced torque capacity and resistance to disengagement, ensuring the integrity and reliability of threaded couplings during drilling operations while reducing material costs.
Implementation Method 1
one or more of the internal and/or external shoulders can include a negative angle (e.g., −10 to −20 degrees, and in an embodiment approximately −15 degrees) to facilitate precise positioning of the pin noses
Implementation Method 2
contact between the first and second pin noses can form a seal therebetween (e.g., when the connection between the male members and the female member is torqued). Such a seal can include a metal-to-metal seal
Implementation Method 3
at least one of the male members can include a tapered external surface (e.g., having a taper angle ranging from 1 degree to 2 degrees, and in an embodiment, approximately 1.75 degrees), which abuts a tapered internal surface of the female member to form a metal-to-metal seal
Implementation Method 4
a bearing journal and/or guide, associated with the exterior threads of either or both male members, can be used to facilitate alignment and engagement between the sets of threads
Data Source
AI summary
Threaded couplings and methods for use in drilling with casing can include first and second male members having exterior threads engaged with interior threads of a female member. Exterior shoulders of the male members can abut interior shoulders of the female member to facilitate placement of the male members such that pin noses thereof are positioned at the center of the female member, where abutment between the pin noses of the male members can form a seal. The shoulders can be provided with negative angles to prevent disengagement. Tapered surfaces can be provided on the male members, to contact tapered surfaces on the female member to form metal-to-metal seals for enhancing the integrity of the connection, a straight thread configuration can be used to maximize the thickness of the coupling, and bearing journals or guides can be used to facilitate engagement of the threads and retention of the engagement.