Casing Window Milling Assembly Conical Section
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Solution Overview
Problem
Current casing window milling assemblies face issues such as premature engagement of reaming and honing mills, increased torque and vibration leading to reduced milling life, and inadequate side force causing the mill head to deviate from the whipstock, resulting in shorter windows and increased operational costs.
Innovation Solution
Incorporation of a conically-shaped tapered section between the mill head and reaming/honing mills, which can be part of the flex-joint or a separate sub-assembly, featuring a low-friction or wear-resistant material like aluminum bronze or tungsten carbide, to delay premature engagement and stabilize the mill head during the milling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the reaming mill and honing mill are disposed toward the upper end of the assembly, then the window can be formed, but the reaming mill and honing mill engage the wellbore casing prematurely causing them to lose milling ability
Solution Approach 1:
A non-cutting intermediary section is introduced between the mill head and the reaming/honing mills. This intermediary section delays the engagement of the reaming and honing mills with the wellbore casing, allowing the mill head to complete its cutting action first. The intermediary section acts as a buffer that prevents premature contact between the secondary mills and the casing, thereby extending their milling ability duration.
2Productivity
If three mills cut the wellbore casing at the same time, then the window can be formed quickly, but severe vibration is excited causing cutters to breakdown and mills to lose cutting ability
Solution Approach 1:
The mill head performs preliminary cutting action on the wellbore casing before the reaming and honing mills engage. The non-cutting intermediary section ensures that the mill head completes its cutting trajectory and creates the initial window opening first. Only after this preliminary action is complete do the reaming and honing mills begin their cutting, which reduces the simultaneous cutting action and thereby decreases severe vibration and cutter breakdown.
3Stability of the object's composition
If the upper mill and high side of the casing contact as a fulcrum, then the mill head can be constrained, but the constraint is lost when mills or casing are worn causing side force to be inadequate
Solution Approach 1:
The non-cutting intermediary section serves as a more reliable constraint mechanism compared to the traditional fulcrum method. By preventing premature engagement of the reaming and honing mills, the intermediary section maintains consistent contact and side force on the mill head throughout the cutting process. This intermediary constraint is more reliable because it does not depend on the wear conditions of the upper mills or casing, thereby maintaining adequate side force to prevent mill head deviation.
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 design prevents premature engagement of reaming and honing mills, reduces torque and vibration, and provides the necessary side force to maintain contact with the whipstock, resulting in longer window lengths and extended milling life, thereby reducing the need for additional milling operations.
Implementation Method 1
a conically-shaped tapered section... featuring a low-friction or wear-resistant material like aluminum bronze or tungsten carbide
Implementation Method 2
decreases the torque exerted on the casing window milling assembly; increases the life of the mills by decreasing vibration of the casing window milling assembly
Data Source
AI summary
Casing window milling assemblies include a conically-shaped section disposed along the tubular of the assembly. This conically-shaped section is a non-cutting portion that is preferably tapered toward the mill head. The conically-shaped section may be part of a flex-joint section of the assembly. Alternatively, the conically-shaped section may be its own sub-assembly secured above the flex-joint. In still another embodiment, the conically-shaped tapered section may be part of the upper mill section of the casing window milling assembly. In one embodiment, the conically-shaped section is disposed along the upper mill section below one or more secondary mills such as a reaming mill and a honing mill.