Axially Spaced Sensor Arrangement for Drilling Position Accuracy
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Solution Overview
Problem
Current methods for determining the position of a bottom hole assembly during drilling are inaccurate due to thermal expansion, stretching, compression, and buckling of the drill string, leading to significant discrepancies in borehole length measurements, which can result in the borehole deviating from its intended path and causing legal and operational issues.
Innovation Solution
A sensor arrangement with axially spaced thermoelectric sensors forming a panoramic thermal camera provides real-time position and movement information by detecting temperature variations, allowing correlation with pipe tally and measured depth, and enabling accurate determination of axial progression and angular movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If driller's depth measurements are used to determine borehole position, then the measurement process is simple, but the measurement precision deteriorates due to thermal expansion, stretching, compression, and buckling of the drill string
Solution Approach 1:
The patent replaces the mechanical measurement system (driller's depth measurements based on drill string length) with an acoustic measurement system (acoustic travel time between sensors). This substitution eliminates the problems of thermal expansion, stretching, compression, and buckling that affect mechanical measurements, as acoustic wave propagation is not affected by these mechanical deformations of the drill string.
Solution Approach 2:
The patent introduces acoustic waves as an intermediary medium to transfer position information. Instead of directly measuring drill string length, the system uses acoustic travel time between sensors as an intermediate parameter that is then correlated with position. This intermediary approach allows accurate position determination without being affected by drill string mechanical deformations.
2Measurement precision
If three axis gravitational and magnetic surveys are conducted to obtain accurate position information, then the measurement precision improves, but the device complexity and time consumption increase
Solution Approach 1:
The patent replaces complex gravitational and magnetic survey systems with a simpler acoustic measurement system. The acoustic system uses basic acoustic sensors and wave propagation measurements, eliminating the need for complex gravitational and magnetic field measurement equipment while achieving comparable or superior position accuracy.
Solution Approach 2:
The acoustic measurement system enables continuous position monitoring during drilling operations, whereas gravitational and magnetic surveys require periodic interruption of drilling. The acoustic sensors continuously measure acoustic travel time, providing real-time position information without stopping the drilling process, thereby maintaining continuous useful action.
3Measurement precision
If three axis gravitational and magnetic surveys are conducted to obtain accurate position information, then the measurement precision improves, but the loss of time increases due to lifting and holding the bottom hole assembly motionless
Solution Approach 1:
The acoustic measurement system allows position measurements to be taken continuously during drilling operations without interrupting the drilling process. The acoustic sensors remain in place and continuously monitor acoustic travel time, providing position information in real-time. This eliminates the time loss associated with lifting and holding the bottom hole assembly motionless during gravitational and magnetic surveys.
Solution Approach 2:
The patent uses acoustic waves as an intermediary to transfer position information during continuous drilling operations. The acoustic measurement process does not require interrupting drilling or moving the bottom hole assembly, as the acoustic waves can propagate through the drilling fluid and formation while drilling continues, enabling time-efficient measurements.
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 solution enables precise measurement of borehole depth and position, reducing inaccuracies and allowing for autonomous drilling control, while also detecting changes in formation material and enhancing the accuracy of traditional drilling surveys.
Implementation Method 1
A sensor arrangement with axially spaced thermoelectric sensors forming a panoramic thermal camera provides real-time position and movement information by detecting temperature variations
Data Source
Figure 1~2
AI summary
A sensor arrangement is described comprising a sensor housing (28), a first sensor (30) sensitive to a downhole parameter and carried by the housing (28), a second sensor (32) sensitive to the same downhole parameter as the first sensor (30) and carried by the housing (28), the second sensor (32) being spaced apart from the first sensor (30) by a fixed distance D in the axial direction of the housing (28), and a control unit (38) operable to monitor the outputs of the first and second sensors (30, 32) to ascertain information relating to the position, movement and/or related information of the housing (28). A related operating method is also described.