Trends in Monitoring H2S Hazards

We’ve seen an increase in the overall quality of systems that are more reliable, robust, and require much less maintenance.

• By Keith Rhodes
• Jul 01, 2012

As the price of oil pushes towards all-time highs, domestic land-based exploration and production are at near-record levels, particularly in the various shale formations throughout the United States. The largest shale drilling sites are located in remote areas of Texas, the Dakotas, and Pennsylvania, among other states. One of the dominant hazards associated with drilling in the shale formations is the prevalence of high concentrations of hydrogen sulfide (H2S), which occurs naturally in crude oil and gas.

In high concentrations, H2S is extremely toxic. It has an Immediately Dangerous to Life and Health (IDLH) threshold of 100 ppm. Several of the shale formations contain high concentrations of H2S, posing a threat to human life in and around the drilling sites.

To mitigate this threat, E&P companies routinely deploy area gas monitoring systems on their sites. Drilling typically takes place in very remote and uninhabited forested areas. Historically, one of the most common challenges in utilizing permanently mounted monitoring systems was lack of power at the site where the system would be mounted. Products recently have been developed that specifically address some of the unique applications in detecting H2S and combustible gases in remote drilling locations with limited power availability.

Products released in 2011 are capable of being powered by batteries or solar power stations, utilizing state-of-the-art sensing technologies for the detection of toxic gases. Highly customizable for individual applications, these products have entity approval through CSA and are suitable for Class I Division I or Class I Division 2 areas.

Three Trends to Watch
Versatile products with wireless transmission: E&P companies demand systems that can be quickly deployed, can monitor up to 16 remote areas around a drilling site, and report back to a central controller. Wireless solutions are growing for the oil and gas industry for good reasons:

A common complaint heard throughout the oil and gas industry is the issue of frequency interference at multiple drilling rig sites that have all employed different gas detection systems. A transmitter with a toxic sensor solves that issue and, when fitted with a lithium ion battery and H2S sensor, can monitor for H2S and report near-real-time readings back to a central controller. Each transmitter has its own unique programmable address matching that of the controller to ensure proper communication with the right transmitter. Ultimate flexibility allows sites to employ multiple systems within close proximity without cross interference. Controllers always should have wireless master and slave operation, which allows detectors to be either hard wired or tethered from the detector up to distances of 350 feet. A 16-channel controller powered by a 12-volt battery and solar panel can transmit all of the information wirelessly with one radio, thus eliminating the need to manage and maintain multiple radios.

Agility and expertise: Like those in most industries, oil and gas customers are continually being asked to do more work with fewer people. Oil companies now expect suppliers to be very consultative in their relationship. Most E&P companies are looking for more than just a supplier of equipment; they are looking for a partner that can design, commission, and maintain the gas detection system. It's a serious business where a lack of agility can to lead to high cost and a lack of expertise can lead to a deadly result. It's not just about how good the equipment is -– it's about the knowledge and core values of your gas detection partner.

For example, gas detection engineers are frequently asked where to place sensors. In the past, most gas detection manufacturers were hesitant to make this kind of recommendation. Now, with the availability of plume modeling software that takes into account potential leak sources and wind direction, gas detection experts can help to provide real guidance in sensor placement in any operating facility. But the key is to consult experts.

Redundancy, SIL 2, and PFD: One trend that continues to gain steam is the demand for systems that provide redundancy and have at least a safety integrity level of 2 ("SIL 2"). This has had a large influence on how gas detection manufacturers design products, beginning with product concept, then design, then manufacturing. The net effect has been an increase in the overall quality of a system that is more reliable, robust, and requires much less maintenance. The industry also has become very adept in understanding PFD (Probability of Failure on Demand) calculations. Customers are beginning to ask for PFD calculations and have a keen interest in the maintenance requirements necessary in order to maintain a SIL-rated system.

Customers are starting to learn that not all SIL-rated systems are alike; one must read the fine print. One manufacturer may be SIL 2 compliant but may require maintenance on that device four times per year, where another manufacturer requires maintenance only one time per year. Multiply the number of points at a given site, and the total cost of ownership begins to add up.

This article originally appeared in the July 2012 issue of Occupational Health & Safety.