Gravity Based Fluid Trap for Drilling Friction Reduction
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Solution Overview
Problem
Conventional drilling techniques face challenges at greater water depths and in deviated wells due to increased weight and friction forces, which limit the reach of the drill string and increase the risk of formation fluid penetration and blowouts, requiring frequent casing installations and increased equipment weight and friction.
Innovation Solution
A method and device utilizing a dual pipe conduit drill string with a u-shaped well bore section, where a denser fluid is circulated in the outer annulus and a less dense fluid within the drill string, leveraging density differences and gravity to separate fluids and reduce friction, allowing for extended drilling without casing installation and enhanced safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the drill string weight is increased to maintain pressure control at greater depths, then the pressure control capability is improved, but the friction forces and equipment load increase excessively
Solution Approach 1:
The patent introduces a buoyancy mechanism where the drill string is made partially buoyant by filling it with a light fluid (such as air or gas) instead of traditional heavy drilling mud. This counteracts the weight of the drill string, reducing the friction forces and equipment load while maintaining sufficient pressure control capability through the buoyant force and fluid pressure differential.
Solution Approach 2:
The patent changes the density parameter of the fluid inside the drill string from heavy (traditional drilling mud) to light (air or gas). This parameter change fundamentally alters the weight balance, reducing the effective weight of the drill string and consequently the friction forces, while still allowing pressure control through the density difference between the light internal fluid and the heavier external formation fluids.
2Length of moving object
If the drill string length is increased to reach deeper wells, then the drilling reach is improved, but the weight and friction forces increase beyond equipment limits
Solution Approach 1:
By making the drill string partially buoyant through the use of light fluids (air or gas) inside the string, the patent reduces the effective weight per unit length. This allows the drill string to be extended to greater lengths without the friction forces and equipment load increasing beyond the limits of conventional equipment, as the buoyant force counteracts the gravitational force on the extended string.
3Reliability
If casing or liners are installed frequently to control pressure, then the pressure control safety is improved, but the drilling time and complexity increase
Solution Approach 1:
The patent changes the fluid density parameter inside the drill string to create a permanent pressure differential that prevents formation fluid penetration. By using a light fluid (air or gas) inside the drill string versus heavier formation fluids outside, the pressure control is maintained continuously without requiring frequent installation of casing or liners, thus reducing drilling time and complexity while maintaining safety.
4Adaptability or versatility
If the well deviates from vertical direction, then the drilling versatility is improved, but the drill string contacts the bore hole wall increasing friction
Solution Approach 1:
The patent applies buoyancy to counteract the gravitational force on the drill string, reducing the normal force between the drill string and the bore hole wall. This is particularly important in deviated wells where the drill string would otherwise rest against and friction against the well wall. The buoyant force reduces this contact pressure, thereby reducing friction forces and enabling better drilling versatility in deviated configurations.
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 reduces friction forces, allows for longer drilling without casing installation, and enhances safety by maintaining control over formation pressures, enabling deeper and more horizontal drilling with reduced equipment weight and increased reach.
Implementation Method 1
feeding a first fluid with a first density in the outer annulus above the u-shaped section, providing a second fluid with a second density within the drill string and around the tool; wherein the first density is larger than the second density
Implementation Method 2
A method and device utilizing a dual pipe conduit drill string with a u-shaped well bore section, where a denser fluid is circulated in the outer annulus and a less dense fluid within the drill string, leveraging density differences and gravity to separate fluids
Implementation Method 3
The buoyant force reduces the effective weight of the drill string, decreasing friction forces between the drill string and well bore wall
Data Source
AI summary
A method to be used when performing drilling in a well bore, comprising: - positioning in the well bore a drill string comprising at least two pipe conduits, an upper end and a lower end comprising a drilling tool, thereby forming an outer annulus between the well bore wall and the drill string; - drilling a well bore section comprising at least one u-shaped section; - feeding a first fluid with a first density into the outer annulus above the u-shaped section, - providing a second fluid with a second density within the drill string and around the tool; wherein the first density is larger than the second density is disclosed. A device for performing the method is also described.