Rotary Shoulder Drill Pipe Connection for Box Swell Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional API 5-inch drill pipes suffer from poor hydraulic efficiencies and mechanical performance due to buckling, box swell, pin collapse, and premature fatigue failure, leading to misalignment and permanent damage in threaded connections under axial, torsional, and bending loads.
Innovation Solution
The development of a drill pipe with a rotary shoulder connection featuring angled and/or curved primary and secondary shoulders, optimized dimensions, and surface treatments like cold rolling and fluoropolymer coating, which enhances alignment, reduces deformation, and improves torsional strength and hydraulic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If standard tapered thread connections are used, then connection strength is improved, but box swell and pin collapse occur causing misalignment and permanent damage
Solution Approach 1:
The patent changes the geometric parameters of the thread connection by introducing angled shoulders (e.g., 15-30 degrees from perpendicular) and optimized shoulder positions. This modifies the load distribution parameters, transferring axial loads away from the tapered threads to the angled shoulders, thereby preventing box swell and pin collapse while maintaining connection strength
Solution Approach 2:
The connection structure is segmented into distinct functional zones: tapered threads for engagement and load distribution, angled primary shoulders for axial load bearing, and angled secondary shoulders for additional support. This segmentation allows each component to handle specific loads appropriately, preventing the combined failure mode of box swell and pin collapse
2Force
If high axial compressive loads are applied, then drilling depth is improved, but box swell forces deform the box connection outward
Solution Approach 1:
The patent extracts the axial load-bearing function from the tapered threads and transfers it to the angled shoulders. The shoulders are specifically designed with angles (15-30 degrees) that allow them to carry high axial compressive loads without deforming the box connection, thereby separating the load-carrying function from the threading function
3Productivity
If conventional drill pipe design is used, then standard hole drilling is achieved, but hydraulic efficiency is poor and buckling occurs
Solution Approach 1:
The patent optimizes the outer diameter and wall thickness parameters of the drill pipe to improve the strength-to-weight ratio and prevent buckling. The tool joint dimensions are also optimized to reduce drag and improve hydraulic efficiency, allowing better fluid flow characteristics and reduced energy loss during drilling operations
4Strength
If tool joint outer diameter is increased, then connection strength is improved, but fishability and hole cleaning are reduced
Solution Approach 1:
The patent optimizes the tool joint outer diameter parameters to achieve a balance between connection strength and operational ease. By carefully selecting the OD within specific ranges and optimizing the shoulder angles, the design maintains sufficient connection strength while minimizing the tool joint size to improve fishability and hole cleaning capabilities
Data Source
AI summary
A drill pipe comprises a drill pipe body and a tool joint that comprises a rotary shoulder connection is disclosed. The rotary shoulder connection comprises: a box connection, wherein the box connection has a box outer radius, a box counter bore radius and a box inner radius, and box threads having a box thread form cut along a box taper; a pin connection, wherein the pin connection has a pin outer radius, a pin cylinder radius and a pin nose radius, and pin threads having a pin thread form cut along a pin taper to align with the box threads inside the box connection; and a primary shoulder connection comprising: a primary box shoulder that is angled or curved; and a primary pin shoulder that is angled or curved. Methods of using the drill pipe are also disclosed.