Rotating Drill String Sub Agitator for Cuttings Redistribution
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Solution Overview
Problem
In horizontal drilling, the accumulation of cuttings in the low side of the wellbore due to insufficient viscous forces from the drilling mud leads to increased drag, wear, and the likelihood of downhole problems such as stuck pipe, reducing drilling productivity.
Innovation Solution
A rotating drill string sub with an agitator and standoff elements is inserted into the drill string to redistribute wellbore cuttings into the drilling fluid flowstream, utilizing a helically arranged blade and groove design that prevents contact with the wellbore wall and enhances the augering effect to move cuttings from high to low concentration areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If horizontal drilling is performed, then access to subsurface geological strata is achieved, but cuttings accumulate in the low side of the wellbore due to insufficient viscous forces from the drilling mud
Solution Approach 1:
The drill string is segmented by inserting a separate subtool between existing drill string components. This subtool includes an agitator with multiple blades arranged in a specific pattern, which segments the cuttings flow and redistributes them throughout the wellbore annulus, preventing accumulation in the low side.
Solution Approach 2:
The subtool acts as an intermediary device between the drill string and the cuttings. It includes an agitator with blades that interact with the cuttings and drilling fluid, creating turbulence and redistributing cuttings throughout the wellbore annulus, thereby preventing their accumulation in the low side.
2Productivity
If cuttings accumulate in the low side of the wellbore, then drilling can continue, but drag on the drill string increases
Solution Approach 1:
The subtool segments the cuttings flow by introducing an agitator with multiple blades that create multiple flow paths. This segmentation distributes cuttings throughout the annulus rather than allowing concentration in the low side, thereby reducing drag on the drill string while maintaining drilling continuity.
Solution Approach 2:
The rotating agitator creates turbulent flow patterns and mechanical mixing action that prevents cuttings from settling in the low side. The blades create vortices and flow disturbances that continuously move cuttings throughout the annulus, reducing accumulation and associated drag forces.
3Productivity
If cuttings accumulate in the low side of the wellbore, then drilling can proceed, but wear on the drill string increases
Solution Approach 1:
The subtool segments the cuttings distribution by introducing an agitator with multiple blades arranged in a specific pattern. This creates multiple flow paths that distribute cuttings throughout the wellbore annulus, preventing concentration in the low side and thereby reducing wear on the drill string while maintaining drilling continuity.
Solution Approach 2:
The subtool serves as an intermediary protective device between the drill string and the cuttings. The agitator blades create turbulent flow that prevents cuttings from directly contacting and wearing the drill string, thereby reducing wear while allowing drilling to continue.
4Productivity
If cuttings accumulate in the low side of the wellbore, then drilling can continue, but the likelihood of stuck pipe increases
Solution Approach 1:
The subtool segments the cuttings flow by introducing an agitator with multiple blades that create multiple flow paths throughout the annulus. This segmentation prevents cuttings from concentrating in the low side, thereby reducing the risk of stuck pipe while maintaining drilling continuity.
Solution Approach 2:
The rotating agitator creates continuous turbulent flow and mechanical mixing action that prevents cuttings from settling and forming packed beds in the low side. This continuous mixing action maintains wellbore cleanliness and reduces the likelihood of stuck pipe while allowing drilling to proceed.
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 effectively reduces the settlement of cuttings on the low side of the horizontal wellbore, minimizing drag and wear on the drill string and reducing the risk of downhole issues, thereby enhancing drilling efficiency and productivity.
Implementation Method 1
a helically arranged blade and groove design that prevents contact with the wellbore wall and enhances the augering effect to move cuttings from high to low concentration areas
Implementation Method 2
Each of the standoff elements contains abutment surfaces, wherein the abutment surfaces comprise an outer diameter that is greater than the outer diameter of the agitator, so that the agitator is prevented from contacting the wall of the wellbore
Implementation Method 3
As the mud flows up through the annulus, the viscosity of the mud is sufficient to exert a vertical force on the cuttings that overcomes the weight of the cuttings
Implementation Method 4
the direction of the flow of the mud is directly or nearly directly opposite to the gravity forces on the cuttings
Data Source
AI summary
A rotating drill string sub redistributes wellbore drill cuttings into the drilling fluid flowstream to improve the efficiency of the drilling operation. Standoff elements are located on each side of an agitator, all configured on a relatively short section of drill pipe. The agitator comprises a plurality of alternating blades standing radially outward from and arranged helically about the axis of the sub, and grooves located between pairs of adjacent blades, each groove comprising a flow channel that is open at both ends of the agitator. The standoff elements contain abutment surfaces having an outer diameter greater than the outer diameter of the agitator, so that the agitator is prevented from contacting the wall of the wellbore and therefore does not experience the forces that the standoff elements experience.