Downhole Tool String Spacer Placement for Mud Cake Friction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Downhole tools face movement impediments due to mud cake formation in boreholes, leading to increased head tension and unpredictable movement, which can result in reduced productivity and the need for costly fishing operations.
Innovation Solution
A manufacturing system that uses a design device to determine optimal spacer configurations along the downhole tool string based on expected contact forces and head tension, reducing contact with mud cake by strategically placing standoffs and rollers to minimize friction and movement resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the downhole tool string is deployed without spacers, then the device complexity is reduced, but the head tension required to move the tool increases and movement becomes unpredictable due to mud cake contact
Solution Approach 1:
The tool string is segmented with spacers placed at specific intervals along its length. These spacers divide the continuous contact surface into discrete segments, allowing the tool to maintain controlled contact with the mud cake at predetermined locations while reducing unpredictable friction along the entire tool surface.
Solution Approach 2:
Spacers act as intermediary elements between the downhole tool string and the mud cake. These spacers are specifically designed to contact the mud cake at controlled points, mediating the interaction between the tool and formation to provide predictable friction characteristics while protecting the main tool body from direct mud cake contact.
2Ease of operation
If spacers are added to reduce mud cake contact, then movement predictability improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
Rather than uniformly distributing spacers along the entire tool string, the invention applies spacers with local quality - placing them strategically at specific locations where mud cake contact is most problematic. Each spacer is positioned to address local contact issues based on expected tool-borehole interaction patterns, optimizing performance while minimizing overall complexity.
Solution Approach 2:
The invention uses partial action by implementing spacers at only the critical locations along the tool string where mud cake contact occurs, rather than providing continuous protection. This selective placement achieves sufficient movement predictability without the excessive complexity of a fully spaced configuration.
3Force
If the tool string contacts mud cake, then friction increases causing higher head tension, but adding spacers to reduce contact increases device complexity
Solution Approach 1:
The invention extracts the harmful contact function from the main tool body by removing direct contact between the tool string and mud cake at critical locations. Spacers are used to take out the contact function and relocate it to dedicated elements that are specifically designed and positioned to manage friction, thereby reducing the overall force required to move the tool while adding minimal complexity.
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 head tension required to move the downhole tool string, enhances movement predictability, and decreases the likelihood of tool sticking, thereby improving operational efficiency and reducing the need for costly interventions.
Implementation Method 1
the mud cake may contact the downhole tool, thereby causing friction that resists movement of the downhole tool
Data Source
AI summary
Techniques for improving implementation of a downhole tool string to be deployed in a borehole formed in a sub-surface formation. In some embodiments, a design device determines a model that describes expected relationship between properties of the downhole tool string, the borehole, the sub-surface formation, and mud cake expected to be formed in the borehole; determines calibration locations along the borehole based on properties of the borehole; determines candidate spacer configurations based on contact force expected to occur at contact points between the downhole tool string and the mud cake when deployed with each of the candidate spacer configuration via the model; and determines a final spacer configuration to be used to attach one or more spacers along the downhole tool string based on expected head tension to move the downhole tool string when deployed in the borehole with each of the candidate spacer configurations via the model.