By Saule Tasboulatova
NCOC press service informed “AkZhaik” today that inspection of Kashagan pipeline is in progress. The results of laboratory analyses showed that pipeline cracking was caused by SSC - sulphide stress corrosion cracking.
Press release reads that after the start of production from the Kashagan field on 11 September 2013, the operations had to be stopped on 24 September, since a gas leak was detected in the onshore section of the gas pipeline running from D Island to the onshore processing facility “Bolashak”.
“In accordance with regulations the Department of Emergency Situations and relevant authorities were immediately informed. The access to the line was secured and the respective joint replaced. Production was resumed and stopped again on October 9th after a seep was detected. Following repair of the affected joint, pressure tests were performed in a fully controlled environment revealing some other potential seeps. The production was stopped and a thorough investigation was launched”.
Management of Investigation
“Immediately after the initial event, the Consortium established a dedicated action team, composed of highly experienced subject matter experts, including those from the national company JSC KazMunayGas, which commenced inspections and initial analysis. This team is still operational. In addition to the investigation and pipeline repairs, excavations of sections of pipeline were conducted to ascertain if there were any possible visual indications of potential leaks”.
Re. Lab Analysis NCOC Reported the Following:
Some of the corrupt parts of the pipeline were sent to Cambridge (TWI Laboratories) in England, where the immediate cause of the pipeline failures was traced to be sulphide stress cracking (SSC). This mechanism occurs when hard/brittle steel is exposed to high H2S concentrations in the presence of water, which results in micro-fissures in the steel. The Kashagan field produces oil and gas with an H2S content amongst the highest in the world, and the specifications of the steel properties for the pipelines, their construction and installation methodology were specifically designed to cope with high H2S content and the presence of water and approved by the State as being correct for the pipelines in question. The Venture is working with the pipeline contractors, which are of the highest international quality for these materials and used by the major oil and gas companies, to ascertain the reasons for the perceived difficulties. The investigation continues in the lab where material experts are now investigating the pipeline joints to identify the root cause of the incidents. Some of the necessary tests take several weeks and it is anticipated that the final report will be available when all such tests and conclusions have been reached.
About the System of Intelligent Pigging
The Consortium is committed to a safe start up of the project, hence the integrity of the facilities is treated as a priority. Although gas leaks have neither been observed in the offshore gas pipeline nor in the oil pipeline, the Consortium decided to carry out a full inspection of both pipelines to ensure 100 percent integrity of the facilities before resuming operations.
One of the best methods for pipeline inspection is so-called ‘intelligent pigging’, sending different gauges (robots) through the entire length of the pipelines (both lines are approximately 90 km long) to conduct an accurate inspection of the pipelines from inside. The objective of intelligent pigging is to map defects of the pipe. In order to get accurate results this method requires draining of the lines, followed by intense cleaning. The cleaning operation is planned to be completed by early December. All the equipment required for the intelligent pigging campaign has been prepared for operation pending completion of the cleaning. Thereafter the intelligent pigging operation will be conducted, which consists of several runs of the equipment along the pipelines with different inspection devices. The data gathered in the course of the inspections will require thorough analysis and interpretation, before a profound conclusion can be made. The intelligent pigging is expected to provide clarity on the extent of the defects in the gas pipeline and potential defects in the oil pipeline. The final results of intelligent pigging data interpretation are expected in early 2014”.
“In the meantime, as a further measure to identify any potential issues, further significant sections of the onshore parts of the gas and oil pipelines have been uncovered, allowing for visual inspection of the pipeline from the outside. This campaign revealed no anomalies in the oil pipeline but showed additional locations on the onshore part of the gas pipeline that provided doubtful visual results that still need the confirmation of the intelligent pig before being finally assessed for integrity.
The offshore gas pipeline has been kept under pressure for several weeks and was carefully monitored during that period. No indications for any leaks in the offshore section such as a decrease in the gas pressure have been found. Although the excavation campaign has been completed it is not exhaustive in its findings”.
“Discussions about remedial actions and timelines for implementing these as well as serious predictions of the restart of production can only be made, when the root cause of the defects has been identified, and the extent of defects has been mapped. The dates which have recently been spread in the media are purely speculative rather than fact based and appropriate announcements can only be made when the position is clear and the relevant authorities involved.