Ensuring Plant and Community Safety with ELDSTM Technology
In 2007, Chevron and China National Petroleum Corporation (CNPC) signed a 30–year production–sharing contract for the joint development of the Chuandongbei natural gas field in central China. Chevron is the operator of the project that will produce 7.6 billion cubic metres of gas a year to meet China’s rapidly growing demand for energy. At an estimated capital cost of $6.4 billion, it is one of the largest investments in China’s petroleum sector.
Chuandongbei is a sour gas development consisting of several fields with an estimated resource base of 5 trillion cubic feet of natural gas. The fields contain dry gas with very high levels (8-17%) of hydrogen sulphide (H2S). A blowout at a well on December 23, 2003, operated at the time by CNPC, turned deadly. According to the news agency Reuters, the leaking sour gas “turned 25 sq km (10 sq miles) of farmland into a lethal zone, killing 243 people and poisoning thousands as they slept or scrambled to escape a toxic cloud of hydrogen sulphide.” The China Daily newspaper described the tragedy as “the worst of its kind in China’s history”. As a result of this major incident, Chevron and CNPC imposed stringent safety standards in the design of the project and sought to implement the most advanced technology for its gas detection system.
The Senscient Solution
Chuandongbei is situated in a densely populated area, with farms and villages surrounding the operational sites. In selecting gas detection technology, sensitivity and speed of response were paramount to ensure the safety of workers and the neighbouring communities. In the event of a leak of sour gas, the detection system had to be fast but also reliable and robust enough to activate plant emergency shutdown (executive action) and trigger the community alarm and evacuation plan.
The Chuandongbei team was seeking a solution to provide the maximum protection whilst ensuring the project would not be subject to false alarms that would disrupt operations and impact relations with the neighbouring communities. Chevron and CNPC selected Senscient ELDSTM sensors following thorough analysis and testing of commercial alternatives.
Senscient has delivered 268 ELDSTM open-path gas detection systems to the Chuandongbei Gas Project. The systems are a combination of toxic and flammable sensors. ELDSTM detectors provide live information on their operational status, thereby ensuring fail-safe operation. This provides the highest safety integrity level and a significant improvement in performance versus point cell devices that are not fail safe, providing a false sense of security. ELDSTM sensors can detect sour gas over distances of up to 60 meters. By operating at a single absorption wavelength, Senscient’s Harmonic Fingerprint technology is specific to Hydrogen Sulphide, ensuring no false alarms or interference from other gases. With no consumable parts and a patented, automatic, self-testing facility called SimuGasTM, the detectors also provide significant cost savings over conventional fixed point toxic gas detectors.