Magnetic Tool Joint Detection for BOP Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The current method for shutting a well is complicated by tool joints, which the BOP shear rams have difficulty cutting, requiring time-consuming processes and driller judgment to position them accurately.
Innovation Solution
An apparatus and method using primary and secondary magnetic field sources to detect tool joints with different magnetic permeability within a tubular by measuring the rate of change of the magnetic field, allowing for real-time positioning through multiple sense coils that cancel noise and enhance signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the annular BOP is closed to seal around the drill string, then the well can be shut, but the process becomes time-consuming and requires driller judgment due to tool joints interfering with sealing
Solution Approach 1:
The patent replaces the mechanical method of detecting tool joints (pulling the drill string and feeling for increased hook load) with a magnetic field-based detection system. Magnetic field sources and sense coils detect changes in magnetic permeability caused by tool joints, providing automatic real-time positioning data without requiring manual mechanical operations or driller judgment.
Solution Approach 2:
The detection system automatically identifies tool joint positions and provides real-time data without requiring external intervention or driller judgment. The magnetic field sources and sense coils self-monitor the drill string, automatically detecting when tool joints approach the BOP seal area, thereby eliminating the need for manual positioning operations.
2Loss of information
If the drill string is pulled to detect tool joint position by monitoring hook load, then the tool joint position can be established, but the process is time-consuming and requires driller judgment
Solution Approach 1:
The patent replaces the mechanical hook load monitoring method with a magnetic field detection system. Magnetic field sources generate fields that interact with the ferromagnetic tool joints, and sense coils detect the resulting field changes, providing automatic real-time position information without mechanical pulling or load monitoring.
Solution Approach 2:
The patent introduces magnetic field sources and sense coils as intermediary elements between the drill string and the detection system. These intermediaries translate the physical presence of tool joints into detectable magnetic field changes, enabling indirect but accurate real-time position detection without direct mechanical interaction.
3Measurement precision
If multiple sense coils are used to detect magnetic field changes, then noise can be eliminated and positioning accuracy improved, but the device complexity increases
Solution Approach 1:
The detection system is segmented into multiple independent sense coils positioned at different locations around the tubular. Each coil independently monitors magnetic field changes, and their outputs are processed separately before being combined. This segmentation enables noise cancellation through differencing while maintaining modular simplicity in each individual sensing element.
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 approach significantly reduces the time and reliance on driller judgment by providing real-time data on tool joint positions, enhancing the efficiency and reliability of well-shutting operations.
Implementation Method 1
at least one primary magnetic field source adapted to be mounted to an external surface of a tubular wall and establish a magnetic field in a portion of the tubular wall, the magnetic field, in use, reducing the magnetic permeability of the tubular wall portion
Implementation Method 2
at least one secondary magnetic field source adapted to be located externally of the tubular wall portion, the/each secondary magnetic field source being adapted to establish a magnetic field within a throughbore defined by the tubular wall
Implementation Method 3
at least one sense coil, the/each sense coil being adapted to measure a rate of change of the magnetic field within the tubular throughbore
Implementation Method 4
With increased reluctance of the tubular wall portion, more of the magnetic flux will seek out a path of lower reluctance and by bringing the paths through the tubular wall down to a more similar level as the paths through a mass of material that has a magnetic permeability different to that of the surrounding environment within the tubular
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides an apparatus for locating and positioning oilwell tool joints. This invention is particularly useful when the apparatus is placed near a Blowout Preventer (BOP) because it can be used to make sure that a tool joint is not present between the BOP rams. In some embodiments, the invention makes use of magnetic flux creation and detection by electromagnetic coils while a portion of the riser is magnetically saturated by powerful permanent magnets. Different configurations of the driving and sensing coils are possible so that it is possible to locate the tool joints longitudinally and radially within the apparatus. The apparatus is easily retrofitted to existing risers without altering ongoing operations because it can be opened before installation and closed once installed.