Dual Pipe Drill String Spacing Assembly
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Solution Overview
Problem
Dual-member drill strings face challenges in maintaining unobstructed fluid flow through the annulus, particularly in rocky conditions where the slanted face bit cannot advance, leading to restricted fluid flow due to axial movement restrictions and operational stresses.
Innovation Solution
The design incorporates a tubular outer member and an inner member with a spacing assembly, including coil springs, flow spacers, and rolling elements, which create a fluid flow path and prevent axial movement restrictions, ensuring continuous fluid flow by maintaining gaps between components under operational stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner member is restricted axially to prevent premature wear and breakage, then reliability is improved, but fluid flow through the annulus becomes obstructed
Solution Approach 1:
The drill string is divided into outer member and inner member components, with the spacing assembly further segmented into multiple elements (collars, shims, washers) that work together to maintain annular gaps while allowing axial restriction of the inner member
Solution Approach 2:
The spacing assembly acts as an intermediary element between the inner member stop and the outer member shoulder, maintaining the necessary annular gap for fluid flow while allowing the inner member to be axially restricted. The spacing assembly includes collars, shims, and washers that collectively preserve the flow path
2Stability of the object's composition
If the drill string components are constrained to maintain position under operational stresses, then stability is improved, but fluid flow passage becomes restricted
Solution Approach 1:
The spacing assembly is designed to be dynamic rather than rigid, allowing it to adjust under operational stresses while maintaining the annular gap. The combination of collars, shims, and washers creates a flexible spacing system that adapts to stress conditions while preserving fluid flow
Solution Approach 2:
The spacing assembly changes its physical parameters (position, compression) in response to operational stresses, allowing it to maintain stability while preserving the annular gap for fluid flow. The shims and washers adjust their configuration under load to maintain flow passage
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 solution ensures uninterrupted fluid flow through the drill string during drilling and backreaming operations, preventing premature wear and breakage, and accommodating elongation and shrinkage of the outer pipe, thus maintaining effective fluid supply to the downhole tool.
Implementation Method 1
a resilient element, such as a coil spring
Implementation Method 2
The spacing assembly includes a coil spring
Implementation Method 3
rolling elements
Data Source
AI summary
A dual pipe drill string system having increased fluid flow. The dual pipe system comprises a plurality of pipe sections, each pipe section having an inner rod and an outer pipe. The inner rod and the outer pipe of each pipe section may be coupled to the inner rod and outer pipe of an adjacent pipe section. An annulus between the inner rod and the outer pipe defines a fluid flow path through the dual pipe system. The outer pipe defines a shoulder at each end of an individual pipe section. The inner rod defines at least one stop for maintaining the inner rod within the outer pipe. A spacing assembly disposed around the circumference of the inner rod defines paths for fluid flow and maintains a minimum distance between the stop and the shoulder at one end of outer pipe of the pipe section.