Electronic Deadman Circuit for BOP Ram Sequencing
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Solution Overview
Problem
Conventional timing cylinders and hydraulic circuits in blowout preventers often fail to provide consistent and repeatable time intervals between the activation of shear and sealing rams, leading to incomplete or late sealing of wellbores.
Innovation Solution
An electronic deadman/autoshear circuit system utilizing a microprocessor and electric signals to precisely sequence the activation of multiple rams in a blowout preventer stack, eliminating the reliance on hydraulic timing devices and ensuring consistent timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic timing circuits or timing cylinders are used to sequence the activation of multiple BOP rams, then the system can achieve sequential activation of shear and sealing rams, but the time interval between activation of first shear ram and second shear ram becomes inconsistent and non-repeatable
Solution Approach 1:
The patent replaces the mechanical hydraulic timing system with an electronic control system. A microprocessor-based controller receives a signal indicating completion of the first shear ram function and automatically activates the second shear ram after a predetermined time interval. This electronic timing mechanism provides consistent and repeatable time intervals, eliminating the variability inherent in hydraulic pressure and flow rate-dependent timing systems.
2Productivity
If hydraulic pressure and flow rates are used for timing the activation sequence, then the system can sequence multiple BOP rams, but the timing becomes inconsistent leading to potential wellbore sealing failures
Solution Approach 1:
The system incorporates a feedback mechanism where a signal is provided indicating the completion of the first shear ram function. The microprocessor-based controller monitors this signal and uses it as the basis for initiating the timing sequence. This feedback approach ensures that the timing is based on actual operational completion rather than hydraulic pressure variables, providing both precision and reliability in the activation sequence.
Solution Approach 2:
The patent changes the fundamental parameter used for timing from hydraulic pressure/flow rate to electronic time interval. By using a microprocessor to enforce a predetermined time interval between activations, the system achieves consistent and repeatable timing that is independent of hydraulic system variations, thereby improving both timing precision and sealing effectiveness.
3Ease of operation
If a timing cylinder is used to delay activation of sealing rams, then sequential activation can be achieved, but the system becomes more complex and less reliable
Solution Approach 1:
The patent replaces the mechanical timing cylinder with an electronic control system. The microprocessor-based controller automatically manages the sequential activation sequence, receiving signals about completion of previous functions and automatically timing the next activation. This maintains ease of operation through automatic sequencing while dramatically improving the reliability and repeatability of timing intervals.
Data Source
AI summary
A blowout preventer control system comprising: a blowout preventer comprising one or more casing shear rams and one or more blind shear rams; a casing shear ram close chamber; a blind shear ram close chamber; a first SPM valve; a second SPM valve; a first solenoid valve; a microprocessor; and a hydraulic fluid source.