Radioactive Tag Positioning for Tubular String Depth Measurement
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Solution Overview
Problem
Accurate placement and determination of the position of tubular strings and downhole tools in wellbores are challenging due to the flexibility and elongation of tubular strings, leading to improper measurements and placement during drilling and production operations.
Innovation Solution
A system and method that utilize a tubular string with a radiation sensor and processor to determine the position of the distal end by correlating measurements of wellbore fluid properties and radiation intensity from radioactive sources, either artificial or naturally occurring, placed along the casing, allowing for precise positioning without relying on length changes of the tubular string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If tubular string length is increased to reach deeper wellbore locations, then the ability to access deeper formations is improved, but measurement accuracy deteriorates due to flexibility and elongation of the tubular string
Solution Approach 1:
The patent replaces mechanical measurement methods (counting tubulars and measuring lengths) with a radiation-based detection system. Radioactive tags are attached to the tubular string, and a radiation sensor on the logging tool detects these tags to determine depth, eliminating the need to physically measure or count the flexible tubular string components.
Solution Approach 2:
The patent introduces radioactive tags as intermediary markers attached to the tubular string. These tags serve as detectable reference points that allow the logging tool to determine its position relative to the tubular string without relying on mechanical measurements of the flexible string itself.
2Device complexity
If traditional mechanical measurement methods are used to determine tubular string position, then device complexity is reduced, but measurement reliability deteriorates due to flexibility and elongation effects
Solution Approach 1:
The patent replaces mechanical measurement systems with a radiation detection system. Instead of using physical sensors to measure tubular string position mechanically, the system uses radioactive tags and radiation detection to determine position, providing more reliable measurements in flexible tubular strings.
Solution Approach 2:
The patent uses radioactive tags that emit detectable radiation, analogous to using visible markers or color changes. The radiation emission provides a clear, detectable signal that allows the logging tool to identify its position relative to the tubular string, similar to how color changes provide visual position indicators.
3Measurement precision
If radioactive tags are placed on the tubular string for position detection, then position detection accuracy is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent divides the tubular string into segments marked with radioactive tags at specific intervals. This segmentation allows the logging tool to detect position at discrete points along the tubular string, providing accurate position information without requiring continuous complex measurement systems.
Solution Approach 2:
The patent uses radioactive tags as intermediary markers that simplify the detection system. Instead of requiring complex continuous measurement systems, the radioactive tags provide discrete, easily detectable reference points that reduce the complexity of the position detection mechanism while maintaining high accuracy.
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
Enables accurate and precise positioning of tubular strings and downhole tools, reducing errors associated with tubular string flexibility and elongation, and improving the reliability of operations such as perforating and well testing.
Implementation Method 1
A tubular string is disposed in the wellbore and carries at least one sensor along a length thereof, with the at least one sensor comprising a radiation sensor
Data Source
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Figure 4A~4B
AI summary
A system disclosed herein is for determining position of a distal end of a tubular string in a wellbore formed in a subsurface formation. The system includes casing lining the wellbore, with the casing carrying a plurality of radioactive sources. A tubular string is disposed in the wellbore and carries a radiation sensor along a length thereof. A processor is associated with the radiation sensor, and is configured to measure intensity of radiation received from the plurality of radioactive sources, and determine the position of the distal end of the tubular string by correlating a formation or wellbore fluid property that varies as a function of position within the wellbore and the measured intensity of the radiation received from the plurality of radioactive sources.