Ocean Bottom Node Depth Determination via Casing Deformation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ocean bottom nodes (OBNs) for seismic data acquisition face challenges in accurately determining their deployment depth without compromising the casing's integrity, which can lead to water tightness issues and increased costs due to the use of expensive pressure sensors.
Innovation Solution
Incorporating a deformation sensor into the casing of the OBN to measure the deformation caused by water pressure, allowing the processing unit to determine the depth based on the measured deformation without weakening the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is used to determine the depth of the OBN, then the measurement precision of depth is improved, but the device complexity and cost increase, and the casing integrity is compromised
Solution Approach 1:
The patent extracts the depth measurement function from a dedicated pressure sensor and implements it through the existing casing structure. The casing itself becomes the sensing element, with strain gauges attached to measure its deformation under hydrostatic pressure, thereby determining depth without requiring a separate pressure sensor assembly
Solution Approach 2:
The casing is given multiple functions: it serves both as the protective housing for the OBN electronics and as the depth sensing element. By attaching strain gauges to the casing, the same structural component performs both containment and measurement functions, eliminating the need for additional dedicated pressure sensing hardware
2Measurement precision
If a pressure sensor is installed in the OBN casing, then the depth determination capability is improved, but the reliability of the casing watertightness deteriorates
Solution Approach 1:
The patent removes the need for penetrating the casing with pressure sensor ports or channels. Instead, strain gauges are attached to the external surface of the intact casing, allowing depth measurement through casing deformation while maintaining the original watertight seal without any openings or weak points in the housing
3Measurement precision
If an expensive pressure sensor is used for depth determination, then the measurement precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive pressure sensors with inexpensive strain gauges that can be attached to the casing. The strain gauges are low-cost components that measure casing deformation, providing sufficient depth determination accuracy without the high cost associated with traditional pressure sensing devices
Solution Approach 2:
By making the casing serve dual purposes as both housing and sensing element, the patent eliminates the need for separate expensive pressure sensor hardware. The strain gauges attached to the casing provide cost-effective depth measurement by utilizing the existing structural component
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 reliable and accurate determination of the OBN's depth without the need for expensive pressure sensors, maintaining the casing's integrity and reducing operational costs.
Implementation Method 1
The deformation of the casing is function of the water pressure and thus of the deployment depth of the OBN. In particular the hydrostatic pressure increases with water depth.
Implementation Method 2
a deformation sensor, configured to measure the deformation of said casing caused by the water pressure
Data Source
Figure 1
Figure 2A~2C
Figure 3~4
AI summary
A seismic data acquisition device (1) intended to be placed on an ocean bottom floor, comprising a casing (2) defining a chamber that houses at least part of a data acquisition system (10); and a deformation sensor (7) fixed on an inner face (21) of a wall (20) of the casing (2), configured to measure a signal representative of a deformation of the casing (2), said deformation resulting from a water pressure that the casing (2) undergoes on said ocean bottom floor; and a processing unit (4) which is configured to determine a water depth at which the casing (2) is located, according to the signal measured by the deformation sensor (7).