Dual Rod Drill Pipe Fluid Path Design
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Solution Overview
Problem
Drill rod assemblies with inner and outer coaxial drill pipes experience restricted fluid flow paths due to manufacturing variations and design limitations, leading to blockages in the drill string during assembly.
Innovation Solution
The design incorporates an outer drill rod with an internal shoulder and an inner drill rod with an external shoulder, along with a coupling that defines fluid flow passages, ensuring the annular fluid flow path remains unobstructed by limiting the inner drill rod's movement and maintaining fluid communication when the coupling is seated against the outer drill rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the inner drill rod is allowed to move freely within the outer drill rod, then the assembly can accommodate manufacturing variations in length, but the fluid flow path becomes restricted and blocked
Solution Approach 1:
The inner drill rod is designed with dynamic positioning capabilities through multiple potential contact points (shoulders and couplings) that allow it to adjust its position along the outer drill rod. This dynamic arrangement enables the system to accommodate manufacturing variations while maintaining an open fluid flow path, as the inner rod can shift to appropriate positions that prevent blockage.
Solution Approach 2:
The coupling acts as an intermediary element that mediates between the inner and outer drill rods. It provides fluid flow passages that connect the annular flow path to the interior of the inner rod, ensuring continuous fluid communication even when the inner rod is positioned against the outer rod's shoulder. This intermediary structure prevents flow blockage while allowing position adjustment.
2Reliability
If the inner drill rod is constrained to a fixed position, then the fluid flow path remains open, but the assembly cannot accommodate manufacturing variations in drill rod lengths
Solution Approach 1:
Rather than a completely fixed position, the system uses constrained dynamics where the inner rod can move within specific limits defined by the shoulder and coupling interfaces. This allows the assembly to adapt to manufacturing variations while the coupling ensures the fluid flow path remains open by providing alternative flow routes through its passages.
3Length of moving object
If multiple drill rod assemblies are connected in series to form a drill string, then the drill string can extend significant distances, but manufacturing variations cause stack-up problems that block the fluid flow path
Solution Approach 1:
Each drill rod assembly in the string incorporates the dynamic inner rod positioning system with shoulders and couplings. This allows each segment to independently accommodate manufacturing variations, preventing cumulative stack-up problems that would block the fluid flow path in long drill strings.
Solution Approach 2:
The coupling serves as a mediator that ensures fluid communication continuity between adjacent drill rod assemblies. Its fluid flow passages connect the annular flow paths of connected assemblies, maintaining uninterrupted fluid flow through the entire drill string despite variations in individual segment dimensions.
Data Source
AI summary
A drill rod assembly including inner and outer drill rods. The drill rod assembly further including flow passages that are in fluid communication with an annular fluid flow path defined between the inner and outer drill rods. The passages preventing blockage of a drill string fluid flow path when a number of drill rod assemblies are interconnected to form a drill string.