Double-Walled Drill Pipe Sealing for High-Pressure Fluid Drilling
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Solution Overview
Problem
Drilling machines using double-walled drill pipes face high failure rates and short service life, making them unsuitable for meeting the demands of horizontal directional drilling.
Innovation Solution
A double-walled drill pipe design featuring an outer drill pipe, an inner drill pipe, and a drill pipe sealing apparatus that connects the outer and inner pipes through a wall surface through hole, allowing high-pressure fluid injection for drilling while preventing fluid from reaching the driving end, thereby enhancing operational reliability and extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-pressure fluid is injected through the drill pipe for rapid drilling, then drilling efficiency is improved, but the fluid may ingress into the driving end structure causing high failure rate and short service life
Solution Approach 1:
The drill pipe is divided into two separate walls (outer drill pipe wall and inner drill pipe wall) forming a double-walled structure. This segmentation creates distinct fluid channels: the annular space between walls for high-pressure fluid injection during drilling, and a separate bearing chamber for housing lubricating oil. The segmentation prevents mixing between drilling fluid and bearing lubricant, allowing rapid drilling while protecting the driving end structure from fluid ingress.
Solution Approach 2:
The inner drill pipe wall is nested within the outer drill pipe wall, forming a concentric double-walled structure. The bearing chamber is nested within the annular space between the two walls, creating a nested arrangement where the bearing housing is positioned in the annular region. This nesting allows the bearing chamber to be protected from external drilling fluid while maintaining access to the annular fluid channel.
Solution Approach 3:
A fluid separator is introduced as an intermediary component between the annular fluid channel and the bearing chamber. The fluid separator includes a first fluid outlet that selectively allows lubricating oil to flow from the bearing chamber to the bearing, while preventing drilling fluid from the annular channel from entering the bearing chamber. This intermediary mechanism ensures that high-pressure drilling fluid cannot contaminate the bearing lubricant, thereby extending service life while maintaining drilling efficiency.
2Reliability
If a sealed structure is added to prevent fluid ingress, then reliability is improved, but device complexity increases
Solution Approach 1:
The drill pipe structure is segmented into distinct functional zones: an annular fluid channel for drilling fluid injection, a bearing chamber for housing bearings, and a fluid separator interface. This segmentation allows each zone to perform its specific function independently, preventing fluid mixing while maintaining a relatively simple overall structure compared to complex multi-component sealing systems.
Solution Approach 2:
The fluid separator acts as a simple intermediary component that provides effective fluid isolation without requiring complex mechanical seals or multiple moving parts. The fluid separator includes a first fluid outlet with selective flow characteristics that naturally prevent drilling fluid from entering the bearing chamber while allowing lubricating oil to reach the bearing. This intermediary approach achieves reliable fluid isolation with minimal structural 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
The solution improves the operational reliability and extends the service life of the double-walled drill pipe and its driving end structure by effectively using high-pressure fluid for drilling while protecting the bearings from fluid ingress, thus enhancing drilling efficiency and durability.
Implementation Method 1
The drill pipe sealing apparatus is disposed between the outer drill pipe and the inner drill pipe to seal a gap between the outer drill pipe and the inner drill pipe
Implementation Method 2
the wall surface through hole is connected to the fluid guiding hole... configured to inject lubricating oil into the first bearing and the second bearing
Implementation Method 3
The double-walled drill pipe includes a first bearing and a second bearing. The first bearing and the second bearing are disposed between the outer drill pipe and the inner drill pipe
Implementation Method 4
a driving end of the outer drill pipe is provided with an oil passage, and the oil passage is configured to inject lubricating oil into the first bearing and the second bearing
Data Source
AI summary
A double-walled drill pipe includes an outer drill pipe, an inner drill pipe and a drill pipe sealing apparatus. The outer drill pipe includes an axial through hole and a wall surface through hole, and the wall surface through hole is disposed in a wall surface of the outer drill pipe to connect the outside of the double-walled drill pipe and the axial through hole. The inner drill pipe is rotatably disposed in the axial through hole, and includes a fluid guiding hole connected to the wall surface through hole. The drill pipe sealing apparatus is disposed between the outer drill pipe and the inner drill pipe. The drill pipe sealing apparatus is axially located between a driving end and a connecting port of the wall surface through hole connected to the axial through hole. A drilling machine including the double-walled drill pipe is also provided.