By Saule Tasboulatova
Intelligent PIG (Pipeline Inspection Gauge). Photo:NCOC.Gas pipeline inspection with the use of so called “Intelligent PIG” has been completed. Analysis and interpretation of received data are ongoing. They are expecting to get the results at the beginning of 2014. This was reported by NCOC press service today, January 8.
Information provided by the Consortium regarding the current situation with incident investigation is as follows: “As stated in the previous communication, the immediate cause for the leaks, being sulfide stress cracking, has been established. Currently there is an ongoing investigation to establish the cause for the sulfide stress cracking in progress. In response to some views expressed in mass media, Operator states that under no circumstances gas hydrates formation could cause sulfide stress cracking. The hydrates formation occurs when natural gas components combine with water to solidify at temperatures higher than the freezing point of water and may cause partial or complete plugging of gas transportation lines. Sulfide stress cracking cannot be connected to or may be caused by hydrates formation. Moreover, Operator also states that to date Kashagan production facilities have not experienced hydrate formation.
Verification of each instance of suspicion of a leak / defect by means of excavations and removal, if necessary, of sections of pipeline is in progress. Previous media reports of number of the defects are pure speculations.
The inspection by the so called Intelligent PIG (Pipeline Inspection Gauge) is in progress and goes according to the plan. This process has been completed for the sour gas line; the raw data are under review and interpretation. As stated earlier, the results of data interpretation are expected to be available in early 2014. These results will be a part of a report, which will be submitted to ROK authorities as appropriate. Preparations to implement the inspection of the oil line are currently in process.
Laboratory analysis and simulations of the operational environment with samples from the pipeline have reached a conclusion that the specifications for the pipeline material were appropriate for the conditions of Kashagan field. The specifications fully meet requirements of the NACE standards (National Association of Corrosion Engineers), respective ISO standards, and best practices in international oil and gas field development. As was previously communicated, the sour gas line was designed to withstand the expected H2S content and the presence of water.
Operator has begun early consideration of technological scenarios for a safe start up. The scenarios would highly depend on the results of data interpretation as well as many other factors. However, in Operator’s view, the dates that have recently been circulated in the media are mere speculations and do not reflect plans and intentions of the Consortium”.
Information about diagnostic PIG is published on NCOC website. The PIG allows to find cracks and crack-like defects, including sulfide stress corrosion cracking and also measures the pipe wall thickness. The PIG was delivered by Weatherford company from the previous place of its use in the Barents Sea to D Island, Kazakhstan.
With the use of PIG the total gas pipeline length (96 km) has been already examined. As preventive measure the Consortium will conduct the inspection of the crude oil pipeline from D island to onshore complex.
Pipeline expert and our source familiar with the matter, whom we approached for the consultation, said that if everything is so good, then there should be no sulfide cracking: “If cracking was indeed of sulfide nature, then it could be caused by two reasons: either the content of sulfides in transported crude (gas) is higher than it was shown in the technical design assignment or the selected type of pipe is not good for the given content of sulfides, provided the sulfide content was shown correctly in technical assignment”.