Eccentric Lobe Reamer Reduces Wellbore Drag and Whirl
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional reaming techniques for wellbores result in increased friction, torque, and drag during drilling, leading to limited wellbore extension and difficulties in passing production strings, while also failing to straighten the well path and are prone to whirl, causing radial impact damage to drill bit cutters.
Innovation Solution
A reamer with an eccentric lobe and roller design that primarily cuts away material near the center of the wellbore's drift, reducing applied power and drag, and limiting whirl by providing an opposing force to the lobe, thereby improving the well path and reducing radial forces on the drill bit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional reaming techniques are used to enlarge the wellbore diameter, then the drift diameter is increased, but friction, torque, and drag during drilling increase significantly
Solution Approach 1:
The reamer is designed with an eccentric lobe configuration where cutting elements are positioned only on one side of the reamer body, creating asymmetric material removal. This local quality approach enlarges the wellbore diameter in the specific area needing expansion while minimizing contact and friction on the opposite side, thereby reducing overall drag and energy loss during drilling operations
Solution Approach 2:
The reamer employs an asymmetric geometry with an eccentric lobe that creates an uneven distribution of cutting elements around the reamer circumference. This asymmetry allows the reamer to enlarge the wellbore diameter effectively while maintaining reduced engagement with the wellbore wall during rotation, thus lowering friction and drag compared to conventional symmetric reamers
2Area of stationary object
If conventional reaming is performed after drilling to enlarge the wellbore, then the drift diameter increases, but additional time and expense are added to well completion
Solution Approach 1:
The reamer is integrated directly into the drilling assembly, allowing reaming operations to be performed simultaneously with or immediately following drilling in a single continuous operation. This merging of drilling and reaming functions eliminates the need for separate reaming runs, thereby reducing overall well completion time and operational expenses while achieving the required drift diameter enlargement
Solution Approach 2:
The reamer is positioned and activated during the drilling process itself, performing the wellbore enlargement action preliminarily before the drilling operation is fully completed. This preliminary reaming action ensures that the drift diameter is adequately prepared during the initial drilling phase, avoiding the need for subsequent separate reaming operations and reducing total project time
3Area of stationary object
If conventional reaming enlarges the entire wellbore diameter, then the drift diameter increases, but the well path is not straightened
Solution Approach 1:
The eccentric lobe reamer removes material locally from specific areas of the wellbore wall rather than uniformly enlarging the entire circumference. This localized material removal allows the reamer to simultaneously enlarge the drift diameter and correct well path deviations by preferentially cutting into high spots or curved sections, thereby straightening the well path while expanding the bore
4Productivity
If rotary tools are used inside the bore, then drilling continues, but whirl occurs causing radial impact damage to cutters
Solution Approach 1:
The asymmetric eccentric lobe configuration creates an unbalanced cutting pattern that prevents the reamer from settling into a stable whirl mode. The uneven distribution of cutting elements around the reamer circumference disrupts the radial forces that typically cause whirl, thereby maintaining drilling continuity while reducing radial impact damage to cutters
Solution Approach 2:
The design accepts that some radial forces will occur during rotation but converts the potentially harmful whirl effect into a beneficial self-correcting mechanism. The eccentric lobe configuration causes the reamer to naturally oscillate in a controlled manner that prevents sustained whirl while still maintaining effective cutting action, thereby transforming a harmful phenomenon into one that protects the cutters from severe impact damage
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 increases the drift diameter of the wellbore, reduces whirl, and minimizes radial impact damage, allowing for more efficient drilling with reduced torque and drag, while maintaining continuous engagement of the cutting teeth and preventing the reamer from digging in and transferring whirl forces.
Implementation Method 1
When rotary tools are used inside a bore there is a dynamic effect called 'whirl' that can occur. This is a secondary mode of motion different from the spinning of the tool, but driven by the rotation of the tool.
Implementation Method 2
Large radial forces develop that cause radial impact damage to the tool's cutters.
Implementation Method 3
cutting away material primarily forming surfaces nearer the center of the drift
Implementation Method 4
Repeated correcting of the direction of the drill bit during sliding causes friction between the wellbore and the drill string greater than when the drill string is rotated.
Implementation Method 5
reduces applied power, applied torque and resulting drag compared to conventional reamers
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention provides a method and apparatus for increasing the drift diameter and improving the well path of the wellbore, accomplished in one embodiment by cutting away material primarily forming surfaces nearer the center of the drift, thereby reducing applied power, applied torque and resulting drag compared to conventional reamers that cut into all surfaces of the wellbore