Case study: The challenges of personnel location in the Kashagan Field
20 February 2019
The Kashagan Field is a very large offshore oilfield located in Kazakhstan’s part of the North Caspian Sea where a number of artificial islands have been built as bases for hydrocarbon extraction. The largest of these is D-island, which is approximately 120,000 m2. Dr. Charlotte Richardson of S3 ID looks at some of the challenges of personnel location in this particularly hostile work environment and explains the solution arrived at to provide effect
The region in which D-island is situated experiences a wide temperature variation from around -35°C in the winter to +40°C in the summer. At these temperatures, the low salinity of the sea means it regularly freezes over, and so the site is shielded by barriers in the sea which help to protect the island from the pressure of the expanding ice in the winter.
The wide temperature range makes the environment very challenging for engineered equipment. Cold weather can be very cruel to battery technology used in wearable equipment. At the opposite end of the scale, in the summer months, temperatures regularly soar up to around 40°C. Equipment installed on the top of the pipe racks could experience the full force of this heat, taking temperatures closer to 80°C, unless some shading from the direct sunlight is provided.
Additionally, the oil in the Kashagan Field contains a high proportion of gas and a very high H2S content of around 19%. This is very unkind to metals; steel, brass, and other materials therefore need protecting from this corrosive gas. It also is highly toxic and so presents a danger to the workers on site.
To help to manage this risk, D-island has been divided into zones; breathing apparatus must be carried in the yellow zones and worn in the red zones. To be allowed to access these areas, personnel are required to complete stringent training. It is key to ensure that only authorised workers are in the restricted zones and a system was needed to oversee this.
S3 ID designed an ATS (Automated Tracking System) to suit the requirements of D-Island and to also mitigate further risks for the site. Because the size and scale of the site is similar to an onshore site, a longer-range tracking technology needed to be used. Ultra-Wide Band (UWB) technology was chosen due to its responsiveness and ability to provide location information to a high precision; UWB uses pulses of radio waves with a central frequency of 6-8 GHz to locate tags precisely. This technology provides visibility for the last location of each worker, which, during an emergency allows the emergency response teams to focus their search more effectively and efficiently in the right areas.
Position of D-Island in Caspian Sea
There are also significant quantities of pipe racks on site, which can be challenging for the various radio technologies due to propagation and reflection, known as multi-path errors. The pipe racks and walkways can be on several levels and there is a requirement to know which level a person is on to inform rescue attempts, so groups of sensors were also installed on stairwells. The UWB technology includes several techniques to introduce resilience to multi-path errors.
The temperature on D-island can drop to -35°C which can cause problems for technology. To overcome the challenges of the extreme cold, the ATEX certified sensors all contain heaters to enable the equipment to operate in this environment. PTC (Positive Temperature Coefficient) heaters were used to supply heat rapidly at very low temperatures and to self limit.
Another challenge presented by D-island is the sheer size of the site and the number of personnel on site at any one time. It is necessary for the safety and efficiency of the facility to locate personnel in real time, so over 600 sensors were installed and over 1,000 tags issued. Typically, to improve location accuracy, sensors are installed in pairs, however as the site is so large, buses are sometimes used to transport personnel. Bus stop zones, each equipped with four sensors due to the larger area, were installed to track personnel entering or alighting from vehicles.
The UWB technology also provides the ability to geo-fence areas and can indicate which zone a person with a tag is in, whether they have permission to be there, and access control technology is linked with this system, providing an additional barrier for restricted areas.
Due to the geography and climate of D-island, evacuation vessels need to be ice breaking and flat-bottomed. There are also temporary refuges at strategic points on site where personnel can seek shelter from the elements, or refill air supplies. It is important to know whether someone has entered or left these refuges and evacuation vessels, so all vessels, refuges and helipads are monitored by the ATS.
Visibility and interaction with long range location technologies
One challenge with long range location systems is that when a person with a tag is far from the sensing device, there can be little feedback that they have been registered. On an offshore rig with a short-range system, this interaction would typically be provided by a display as a person musters, or traffic lights on bridge tracking systems. To provide the peace of mind that the system is functioning correctly, tag checking stations were installed at the exit points to the Living Quarters. In addition to showing the person’s ID details, the battery health status of the tag is also displayed so that batteries can be changed before leaving the safe area if required.
Similarly, the technology was made available to sample the RSSI of the tags during a muster via a calibrated detector and display the information on a portable device so that people on the ground could see that they had mustered.
D-Island in winter
The challenges posed by the unique environment of D-island in the Kashagan Field have been overcome by the design and creation of this bespoke long-range Automated Tracking System. The system aims to provide responsive location information to operators and personnel on site so that, should an incident occur, all personnel can be located as quickly and efficiently as possible. Additionally, it allows the operators to oversee that workers are on site when expected and have visibility that only authorised personnel are working in restricted areas.
This ATS was specifically designed to work in the extreme temperature range and harsh environment of the North Caspian Sea and can be adapted and engineered for use in most locations around the world.
About the author
Dr. Charlotte Richardson is the Product Development Manager at S3 ID Ltd and has been with the company since 2009. S3 ID specialises in personnel location systems for hazardous areas in the onshore and offshore oil, gas and energy industries. Prior to working with S3 ID, Charlotte had various engineering roles and also worked as a lecturer teaching Mechanical Engineering.
Charlotte holds an M.Eng (Hons) in Mechanical Engineering and French and a Ph.D. from the University of Sheffield and also has a P.G.C.E./P.C.E.T. from the University of Huddersfield.
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