Downhole Depth Computation via Accelerometer and Database Correlation
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Solution Overview
Problem
Current methods for determining the depth of a wellbore in subterranean rock formations require separate survey trips, consuming time and resources, and lack accuracy in older wells due to outdated technologies or cost constraints.
Innovation Solution
A method and apparatus utilizing a wellbore tool with an accelerometer and processor that measures acceleration and correlates data from a database to determine depth, allowing for real-time depth calculation and survey association without a separate survey trip, using inertial navigation and preprogrammed data on tubular lengths and geological features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate wireline survey trip is conducted to determine wellbore depth and survey data, then measurement precision is improved, but loss of time and productivity deteriorate due to the additional trip required
Solution Approach 1:
The patent combines depth measurement and survey data acquisition into a single integrated operation. The Bottom Hole Assembly (BHA) simultaneously performs drilling while measuring both depth (via accelerometers and drill string length) and survey data (via gyroscopes and magnetometers), eliminating the need for a separate wireline survey trip and resolving the contradiction between measurement precision and time loss
Solution Approach 2:
The patent introduces an intermediary processing system that receives raw acceleration data from downhole accelerometers and converts it into depth measurements through integration and filtering algorithms. This intermediary processing enables continuous depth measurement during drilling operations, allowing simultaneous depth and survey data acquisition without requiring separate trips
2Measurement precision
If conventional wireline survey methods are used to obtain accurate wellbore profile data, then measurement precision is improved, but device complexity and resource consumption worsen due to the requirement of separate survey equipment and operations
Solution Approach 1:
The patent makes the Bottom Hole Assembly multi-functional by integrating multiple measurement capabilities into a single device. The BHA simultaneously performs drilling, depth measurement (via accelerometers), and survey data acquisition (via gyroscopes and magnetometers), replacing multiple separate devices and operations with one universal tool that reduces complexity while maintaining measurement precision
Solution Approach 2:
The patent merges depth measurement functionality and survey data acquisition into the existing drilling BHA. By combining accelerometers for depth, gyroscopes for orientation, and magnetometers for directional surveying within the same downhole assembly, the system eliminates the need for separate wireline survey equipment and operations, reducing overall device complexity
Data Source
AI summary
A method for determining depth in a wellbore uses inertial navigation in conjunction with a database having one or more measured parameters correlated with depth. The measured parameter may be the lengths of stands forming a drill string, prior survey data relating to a naturally occurring feature such as formation lithology, or data relating to a human made feature such as collars in a casing string. The downhole processor may use accelerometer measurements to calculate a measured depth of a BHA and access the database to retrieve a predicted depth that corresponds with one or more sensor measurements (e.g., motion indicating the addition of a stand to a drill string). Thereafter, if the downhole processor determines that the predicted depth is in agreement with the calculated depth, the processor stores the predicted depth and/or associates the predicted depth with directional surveys taken along the wellbore.