Borehole Depth Measurement Using Inertial and Drill Rig Data
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Solution Overview
Problem
Conventional methods for determining borehole depth, such as wireline encoders and pressure sensors, are prone to errors due to stretching, calibration difficulties, and dependence on specific conditions, making accurate depth measurement challenging.
Innovation Solution
A system utilizing inertial sensors, processors, and memory in a downhole device, combined with drill rig sensors, to determine depth through inertial measurements and additional depth measurements from drill string position, enabling accurate depth calculation without maintaining wireline tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wireline encoders are used to measure depth, then depth measurement is possible, but the measurements are subject to error due to wireline stretching
Solution Approach 1:
The patent replaces the mechanical wireline encoder system with an inertial measurement unit (IMU) that uses accelerometers and gyroscopes to measure depth. This substitution eliminates the mechanical stretching problem inherent in wireline encoders by using inertial sensing technology that is not subject to physical deformation, thereby improving both measurement precision and reliability
Solution Approach 2:
The patent introduces an intermediary integration process that combines inertial measurements from the IMU with depth measurements from a depth sensor (such as a laser distance meter). This intermediary approach allows the system to benefit from the stability of inertial measurements while correcting for drift through periodic calibration with the depth sensor, resolving the reliability issue
2Measurement precision
If wireline encoders are used to measure depth, then depth can be tracked, but the encoders are difficult to set up and calibrate
Solution Approach 1:
The inertial measurement unit is self-contained and requires no external calibration infrastructure. The IMU automatically determines depth through integration of acceleration measurements, eliminating the complex setup and calibration procedures required for wireline encoders. The system serves itself by using its own inertial sensors to compute depth without requiring external reference systems
Solution Approach 2:
Replacing the mechanical wireline encoder system with an electronic inertial sensing system eliminates the physical setup complexity. The IMU can be easily installed in the drill string and begins providing depth measurements immediately without requiring mechanical alignment, tensioning, or calibration procedures
3Measurement precision
If wireline encoders are used, then depth measurement is possible, but synchronizing data between the encoder and downhole tool is problematic
Solution Approach 1:
The patent merges the depth measurement functionality directly into the downhole tool by integrating an inertial measurement unit within the tool itself. This combination ensures that depth data and tool measurement data are naturally synchronized since they are collected by the same device at the same location, eliminating the synchronization problems that arise when using separate wireline encoders and downhole tools
4Measurement precision
If drill string component lengths are summed to approximate borehole length, then depth can be estimated, but the measurement is subject to error due to stretching and compression
Solution Approach 1:
The patent replaces the mechanical measurement approach of summing drill string component lengths with an inertial sensing system. The IMU measures depth through integration of acceleration, which is not affected by the stretching or compression of drill string components. This substitution provides reliable depth measurement even when the drill string undergoes mechanical deformation
5Measurement precision
If pressure sensor-based detection is used, then depth measurement is possible, but the borehole must be full of water limiting use to non-dry holes
Solution Approach 1:
The patent replaces the pressure-based measurement system with an inertial measurement system. The IMU uses accelerometers and gyroscopes to determine depth through inertial navigation, which does not require the presence of fluid in the borehole. This substitution makes the depth measurement system adaptable to both wet and dry borehole conditions, significantly improving versatility
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 precise depth measurement in boreholes by integrating inertial and drill rig data, reducing errors associated with stretching and environmental dependencies, allowing measurement during drilling or tripping operations.
Implementation Method 1
a downhole device comprising at least one inertial sensor
Data Source
AI summary
A system for determining depth within a borehole. The system includes a downhole device having at least one inertial sensor, at least one processor, and a memory in communication with the at least one processor. The memory can include instructions thereon that, when executed, cause the processor to: receive data from the at least one inertial sensor and store the data from the at least one inertial sensor in the memory with respective correlated time values. The system can further include a drill rig having at least one depth measurement device. The at least one depth measurement device can include a drill string position sensor that is configured to produce a measurement indicative of a length of a portion of a drill string removed from a borehole or a wireline sensor that is configured to determine a length of deployed wireline cable.