Dual-Fluid Drill String for Horizontal Directional Drilling
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Solution Overview
Problem
Traditional horizontal directional drilling methods are costly due to the high expense of liquid-based drilling fluids, including labor, delivery, and remediation costs, and inefficient fluid management.
Innovation Solution
A dual-member drill string system using compressed air as the primary drilling fluid, with a minor water-based liquid component for dust suppression and friction reduction, featuring a unique pipe assembly design with a polygonal profile and fluid seals to maintain mutually exclusive fluid paths and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid-based drilling fluid is used, then borehole stabilization and spoil removal are achieved, but fluid cost and environmental impact increase significantly
Solution Approach 1:
The patent extracts the water-based liquid component from the traditional liquid drilling fluid system, retaining only the compressed air as the primary drilling fluid. This extraction eliminates the harmful environmental factors associated with large quantities of liquid fluid while maintaining the core drilling functions through air alone.
Solution Approach 2:
The patent changes the physical state parameter of the drilling fluid from liquid to gas (compressed air). This parameter change fundamentally reduces the quantity of substance required and eliminates the environmental harm associated with liquid-based fluids, while still achieving borehole stabilization and spoil removal through the compressed air medium.
2Quantity of substance
If compressed air is used as primary drilling fluid, then fluid cost is reduced, but fluid management efficiency must be maintained
Solution Approach 1:
The patent segments the fluid paths into two mutually exclusive separate paths: one for compressed air supply and another for liquid component (when used). This segmentation allows independent management of each fluid path, maintaining productivity by enabling precise control over fluid delivery while using minimal quantities of each component.
Solution Approach 2:
The patent introduces fluid seals as intermediary elements between adjacent pipe assemblies to prevent leakage between the mutually exclusive fluid paths. These intermediary seals maintain fluid management efficiency by ensuring that compressed air and liquid components remain separated and contained within their designated paths, preventing cross-contamination and pressure loss.
3Productivity
If dual fluid paths are implemented, then fluid path management is improved, but device complexity increases
Solution Approach 1:
The patent implements a nested structure where the inner pipe is positioned within the outer pipe, creating two concentric fluid paths. This nesting arrangement achieves complex fluid path management (mutually exclusive paths for air and liquid) within a compact structure, reducing overall device complexity compared to separate parallel systems while maintaining improved fluid path management capability.
4Reliability
If fluid seals are placed between adjacent pipe assemblies, then interpath leakage is minimized, but manufacturing complexity increases
Solution Approach 1:
The patent applies fluid seals only at specific locations where adjacent pipe assemblies join, rather than along the entire length of the pipes. This localized application of sealing quality achieves effective leakage prevention at the critical interfaces between segments while minimizing manufacturing complexity by avoiding the need for continuous sealing mechanisms along the entire drill string.
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 system significantly reduces fluid costs and environmental impact by using less fluid overall, maintaining effective borehole stabilization and spoil removal with efficient fluid path management, while minimizing pressure loss and interpath leakage.
Implementation Method 1
A fluid seal is received within the endless groove
Implementation Method 2
The inner member is characterized by a pin end having a polygonal outer profile and an opposed box end having a polygonal inner profile
Data Source
AI summary
A pipe assembly has a hollow inner member nested within a hollow outer member. A series of pipe assemblies are connected end-to-end to form a dual-member drill string useful in horizontal directional drilling operations. The drill string has mutually exclusive first and second fluid paths. Fluid seals, interposed between adjacent inner members of the string, isolate the first fluid path from the second fluid path. Compressed air is delivered into the first fluid path from above ground level, and routed to an underground boring tool. The expelled air and spoils are returned to above ground level by way of the second fluid path. One or more baffle elements are supported on the drill string adjacent the boring tool. The baffle elements are configured to prevent compressed air and spoils from flowing between the walls of the borehole and the drill string.