Downhole Tool Depth Determination via Wireline Log Correlation
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Solution Overview
Problem
In downhole operations, the lack of communication between downhole tools and surface equipment makes it difficult to determine the depth of tools in wellbores accurately, leading to potential safety issues and inefficiencies, as conventional methods relying on temperature and pressure measurements are not precise enough.
Innovation Solution
A system that correlates previously gathered depth-dependent logging data with real-time data from downhole tools to determine their depth, using wireline logs and a controller to enable precise depth determination even without surface communication, allowing for safer and more efficient operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods relying on temperature and pressure measurements are used, then the system can operate without surface communication, but the depth determination precision is insufficient
Solution Approach 1:
The patent introduces wireline logs as an intermediary medium to transfer depth information from the downhole tool to the surface equipment. The wireline acts as a carrier that conveys logging data obtained by the downhole tool, enabling precise depth determination without requiring direct communication between the tool and surface control equipment. This resolves the contradiction by providing a simple intermediary solution that achieves high measurement precision without significantly increasing system complexity.
Solution Approach 2:
The patent replaces conventional mechanical measurement methods (temperature and pressure sensors) with a data communication-based approach using wireline logs. Instead of relying on physical field measurements that indirectly indicate depth, the system uses digital logging data transmitted through the wireline to directly determine depth with high precision. This substitution enables accurate depth determination while maintaining operational simplicity.
2Loss of information
If no communication is available between tool and surface equipment, then the tool can operate independently, but depth information cannot be determined accurately
Solution Approach 1:
The wireline serves as an intermediary communication channel that enables depth information to be transmitted from the downhole tool to the surface equipment without requiring direct electronic communication between them. The wireline carries the logging data obtained by the tool, allowing surface equipment to access depth information while the tool maintains its independent operational capability. This resolves the contradiction by providing a passive information transfer mechanism that does not interfere with the tool's independent operation.
3Measurement precision
If wireline logs are used to determine depth, then precise depth determination is achieved, but additional equipment and procedures are required
Solution Approach 1:
The wireline logging system serves multiple functions: it obtains depth information, provides formation evaluation data, and enables tool tracking throughout the wellbore. By making the wireline system multi-functional, the patent justifies the additional equipment requirements through the versatility and comprehensive data collection capability, achieving high measurement precision while the added complexity is offset by the system's multiple useful functions.
Data Source
AI summary
Techniques for determining depth of a downhole tool in a wellbore include running a first downhole tool into a wellbore on a downhole conveyance; generating time-dependent logging data with the first downhole tool in the wellbore, at least one of the depth-dependent logging data or the time-dependent logging data associated with an electric or a magnetic property of a wellbore casing or a geological formation; correlating at the first downhole tool the time-dependent logging data with the depth-dependent logging data; and based on the correlation, determining at least one of a depth of the first downhole tool in the wellbore or a speed of the first downhole tool in the wellbore.