Comprehensive Safety Monitoring at Well Site Applications using a Three-Tiered Approach

There are a number of challenges when evaluating a safety monitoring solution for well sites: they are typically open areas with constantly changing wind conditions, they are subject to extreme temperatures and humidity, the operational components of the site are often positioned far away from one another, and their remote locations create a challenge for emergency response as well as providing a reliable power source. Well site installations also maintain high-pressure conditions at the well heads, storage tanks, treater sheds, and flare stacks. And some oil fields can also produce high concentrations of hydrogen sulphide gas which is highly toxic and explosive even at low levels. The combination of all these factors create a serious challenge to operators in order to quickly detect leaks, identify whether a toxic and/or combustible gas has been released, and effectively prevent an exposure or ignition event from occurring.

Remote well sites pose an extra challenge as most are without a source of uninterruptible grid-based power. Fortunately, the solution can be found in the form of turbine generators, stand-alone solar powered systems or through TEG power generators if available, but strict power load requirements will limit the number and type of monitoring instruments that can be utilized on the site.

Monitoring Technology Solutions
Even at low levels, %LEL gas releases create the real potential for ignition and explosion, while any toxic gas release into the atmosphere endangers the lives of plant personnel as well as those within the surrounding area, as well as violating regulatory environmental requirements for well site safety. Fixed-point Combustible and H2S gas detectors combined with Ultrasonic leak detection and optical flame detection will form a comprehensive safety umbrella around wellheads. Ultrasonic detection technology will immediately detect a gas leak in virtually any environmental condition. Fixed point detection will accurately identify the presence of toxic and/or combustible gas throughout the well site. Optical flame detection immediately alerts to the ignition of combustible gases.

Ultrasonic is an “emerging” sensing technology that has recently taken its place as a field-proven solution in the safety monitoring industry. For many years now, detecting combustible gas leaks has been accomplished through the use of catalytic bead and infrared point detectors along with open path infrared perimeter detectors. We can now greatly extend the coverage provided by those solutions, as well as overcome some of their serious performance limitations, through the use of ultrasonic gas sensing technology.

Primary advantages of the Net Safety ultrasonic gas leak detector include:
• Detects a gas leak before a hazardous concentration is present
• Not affected by any adverse environmental conditions (wind, rain, fog, snow, ice, or sand)
• The gas cloud does not require contact with the sensor (or beam) in order for detection to take place
• Detection is instantaneous for all types of gas leaks (toxic or combustible)
• Sensors never expire and are calibrated for life at the factory
(performance does not degrade through time)

Fixed point gas detection will always be an integral part of well site safety coverage. As existing oil and gas fields are fully developed we will increasingly see a move to more challenging locations in order to satisfy our energy needs. Safety devices must be versatile and robust to provide the same level of coverage in these difficult applications. SMART detection platforms that are designed to perform in the most extreme conditions, offer a full range of sensor options, and have low power consumption levels are going to provide operators with the greatest coverage with the most reliable performance.

For locations where remote power sources are employed, low power safety monitoring instruments provide a significant advantage in that you can ensure instruments will remain online in the event of power drops or fluctuations. Another consideration is the separated components of the site that require monitoring (wellhead, flare stack, sheds and storage tanks) with individual remote power sources (solar arrays specifically). These can easily be networked throughout the entire site with the simple addition of a THUM WirelessHART Adapter, eliminating the need for expensive wiring, trenching and complex system configuration.

Primary advantages of the Net Safety Millennium II Series of fixed point gas detectors include:

• Extremely low power consumption improves performance, allows flexibility, and lowers overall costs
• Single, dual-channel, or BASIC universal transmitter configurations are completely interchangeable with our field-proven electrochemical, NE-MOS solid state, catalytic bead, and infrared Sensor Technologies
Highly robust construction and reliable performance designed for extreme conditions
Fast digital communication between the sensor and the transmitter [2000ft (600m) separation] with WirelessHART® communications available.

Triple Infrared optical flame detection is proven the most effective flame detection technology available for most industrial applications. It provides extremely fast and accurate response with the highest sensitivity and immunity to false alarm sources for solar-blind UV sources, window contaminates, and both non-modulated and modulated IR sources. Triple IR flame detectors also offer the widest area of coverage and detection distance. In Well site installations there are a number of features specific to the Net Safety Phoenix Triple IR that make it an ideal solution in this application.

Primary advantages of the Net Safety Phoenix Triple IR Flame Detector include:
• Extremely low power consumption increases uptime, allows flexibility, and lowers overall costs
• Highly robust construction and reliable performance Designed for Extreme Conditions
• Automatic Digital Zoom technology provides the most accurate detection of flame which are traditionally difficult to detect
• Field settings for sensitivity and time delay allow for insitu fine-tuning of the detector for optimal performance in a particular installation area.

For many years now, well site safety monitoring has been accomplished through the use of various point detectors along with open path infrared perimeter detectors. Operators can now greatly extend the coverage provided by those solutions, as well as overcome some of their serious limitations, through the use of ultrasonic gas leak sensing technology. As any field personnel can attest, no single sensing technology can solve the entire problem. The vulnerabilities of any one detection solution are offset by the strengths of the others when utilizing a comprehensive approach to coverage. With a combination of detection technologies, hazards have fewer chances of propagating undetected – especially in wellhead applications that are generally remote locations and make responding to a release event such a challenge. Such diverse safety systems, combined with a design that mitigates leakage and eliminates possible ignition sources, provides a sound approach for delivering reliable coverage for any well site.

Author: Larry McGee is a Business Development Manager for Flame & Gas Detection Solutions within Rosemount Analytical - Emerson Precess Management. For more information please contact safety@emerson.com

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Originally Published in Industrial Hygiene News

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