Cased Drilling Negative Pressure Gas Extraction
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Solution Overview
Problem
In cased drilling, frequent assembly and disassembly of the rotary union are time-consuming and costly due to the need for continuous discharge of drill cuttings, especially in discontinuous drilling operations, and there is a lack of efficient methods to collect harmful gases escaping during drilling in contaminated soil.
Innovation Solution
A method and drilling arrangement that generate a negative pressure in the drill pipe using a ring-shaped negative pressure unit, allowing ambient air to be drawn in and harmful gases to be collected, eliminating the need for a special seal between the drill pipe and the inner drilling tool, and featuring a vacuum unit with a discharge nozzle for air and potential cleaning of gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotary union is used to discharge drill cuttings in discontinuous drilling operations, then drill cuttings can be removed from the borehole, but frequent assembly and disassembly are required which is time-consuming and costly
Solution Approach 1:
The harmful gases are extracted from the drill pipe interior through the annular gap between the drill pipe and inner drilling tool. The negative pressure unit creates a vacuum that draws gases out through this gap, eliminating the need for a sealed rotary union and allowing continuous operation without frequent disassembly.
Solution Approach 2:
The annular gap acts as an intermediary pathway for gas removal. Instead of requiring a direct sealed connection through the rotating tool, the gap provides a passive flow path that allows gas extraction while maintaining operational continuity and avoiding frequent assembly/disassembly cycles.
2Object-affected harmful factors
If the drill pipe is sealed to prevent harmful gas escape, then gas containment is improved, but the inner drilling tool cannot move freely and requires frequent disassembly
Solution Approach 1:
Harmful gases are extracted from the drill pipe through the annular gap between the drill pipe and inner drilling tool. The negative pressure unit creates a vacuum that draws gases out through this gap, preventing axial contamination while allowing the inner drilling tool to move freely without requiring disassembly.
Solution Approach 2:
The negative pressure environment created by the vacuum unit establishes a controlled atmosphere within the drill pipe. This inert-like environment prevents harmful gases from escaping axially while allowing radial extraction through the annular gap, maintaining both containment and tool mobility.
3Productivity
If compressed air is introduced into the drill pipe to expel soil material, then drill cuttings can be discharged, but harmful gases are not effectively collected
Solution Approach 1:
Instead of introducing compressed air to expel cuttings (positive pressure approach), the invention uses a negative pressure unit to create a vacuum that draws gases out through the annular gap. This inverted approach—removing gases through suction rather than pushing cuttings out with pressure—enables simultaneous cuttings discharge and harmful gas collection.
Solution Approach 2:
The annular gap, which could be seen as a source of gas leakage, is converted into a beneficial extraction pathway. The negative pressure unit transforms the potential harm of gas escape into a controlled removal mechanism, where harmful gases are actively drawn out through the same annular region.
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 approach enables efficient and environmentally friendly drilling by reliably collecting harmful gases without axial contamination, allowing the inner drilling tool to move freely and reducing the need for frequent assembly and disassembly, while also providing a mechanism for cleaning the discharged air.
Implementation Method 1
a negative pressure is generated in an upper region of the drill pipe in the drill pipe by means of a ring-shaped negative pressure unit, a region with negative pressure is formed in the drill pipe, and the ambient air flows in annularly into the low-pressure area
Data Source
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AI summary
The invention relates to a method and a drilling arrangement for cased drilling, in which a drill pipe 12 is inserted into the ground, at least in an upper region of a borehole to be created, and soil material within the drill pipe 12 is removed by means of a rotating drill bit, and the borehole is then drilled. According to the invention, a negative pressure is generated in an upper region of the drill pipe 12 by means of an annular negative pressure unit 20, thereby creating a negative pressure region within the drill pipe 12, and the negative pressure is adjusted such that ambient air flows into the negative pressure region from above in an annular manner.