Downhole Tool String Segmentation for Depth Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current well survey methods are inefficient due to repeated depth positioning and depth offset issues, leading to substantial delays and inefficiencies in downhole testing operations, as a significant number of test stations require repeated measurements and corrections.
Innovation Solution
A downhole tool string comprising an anchor device, a testing device, and a linear actuator that maintains the tool string in a predetermined position within the wellbore, allowing the testing device to move longitudinally and perform sampling or testing operations without requiring frequent repositioning of the entire tool string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireline conveyance is used to move the testing tool string to different depths, then the testing can be performed at multiple stations, but repeated shifting operations consume valuable rig and personnel time and generate depth offsets requiring periodic correlation passes
Solution Approach 1:
The tool string is divided into a stationary anchor device portion and a movable testing device portion. The anchor device remains fixed at one depth while the testing device can be moved independently to different depths along the wellbore using a linear actuator or downhole tractor mechanism. This segmentation allows multiple testing operations at different stations without requiring repeated retrieval and repositioning of the entire tool string.
Solution Approach 2:
A linear actuator or downhole tractor serves as an intermediary mechanism between the stationary anchor device and the movable testing device. This intermediary enables the testing device to move along the wellbore relative to the anchor device, providing depth positioning capability without requiring surface intervention or repeated wireline conveyance operations.
2Measurement precision
If the entire tool string is repositioned for each test station, then accurate depth positioning can be achieved, but the frequency of repositioning increases operational complexity and time consumption
Solution Approach 1:
The tool string is segmented into stationary and movable portions, allowing the testing device to be repositioned independently without moving the entire assembly. This maintains measurement precision at each test station while eliminating the need for frequent complete tool string retrievals and repositionings, thereby improving operational productivity.
Solution Approach 2:
The system transitions from a static entire-tool-string repositioning approach to a dynamic configuration where the testing device can move independently along the wellbore. The linear actuator or downhole tractor provides controlled movement capability, enabling the testing device to reach different depth positions while the anchor device remains stationary, thus maintaining positioning accuracy without sacrificing productivity.
3Reliability
If repeated shifting operations are performed to ensure accurate depth positioning, then measurement reliability improves, but the number of wireline cycles increases leading to substantial delays and potential replacements/repairs
Solution Approach 1:
By segmenting the tool string into stationary and movable portions, the system achieves reliable depth positioning through the movable testing device without requiring repeated complete tool string retrievals. The stationary anchor device provides a stable reference point while the testing device can be repositioned multiple times using the linear actuator or downhole tractor, reducing wireline cycles and associated delays.
Solution Approach 2:
The anchor device is deployed and secured at the initial position before the testing operations begin. This preliminary anchoring action establishes a stable base that eliminates the need for repeated complete tool string retrievals and repositionings, thereby reducing the total duration of testing operations while maintaining positioning reliability.
4Measurement precision
If multiple depth correlation passes are conducted to correct depth offsets, then positioning accuracy is maintained, but the operational complexity and time requirements increase substantially
Solution Approach 1:
The tool string segmentation into stationary and movable portions simplifies the depth positioning system. The stationary anchor device provides a fixed reference point while the movable testing device can be precisely positioned at different depths using the linear actuator or downhole tractor. This eliminates the need for complex periodic depth correlation passes, reducing operational complexity while maintaining positioning accuracy.
Data Source
AI summary
Apparatus and methods for performing downhole testing. Example apparatus include a downhole tool string for conveying within a wellbore, the downhole tool string comprising an anchor device, a testing device, and a linear or rotary actuator. The anchor device maintains a portion of the downhole tool string in a predetermined position within the wellbore. The testing device is operable to receive a downhole sample from or test a subterranean formation surrounding the wellbore. The linear actuator is connected between the anchor device and testing device, and moves the testing device relative to the anchor device.