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NCOC announces cause of gas leaks at Kashagan oil field 10 декабря 2013, 01:11

Sulphide stress corrosion is the direct cause of the gas leak at the Kashagan field in Kazakhstan.
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At the Kashagan oil field. ©Reuters At the Kashagan oil field. ©Reuters
Sulphide stress corrosion is the direct cause of the gas leaks haunting the Kashagan field, North Caspian Operating Company B.V. (NCOC), the Kashagan field operator, told Tengrinews. The representatives of NCOC pointed out that the inspection at Kashagan is still underway. Some defective parts of the pipeline were sent to Cambridge, the TWI company's lab in Great Britain. The analyses showed that sulphide stress corrosion was the direct cause of the gas leak. Such damage occurs when hard/short steel is constantly under the impact of high concentration of H2S accompanied by water that causes the hairline fractures in the steel. The H2S content in the product of the Kashagan field is among the highest in the world. The Kashagan operator pointed out, that the investigation is continued in the labs, where the experts are studying the pipe junctions to determine the main cause of the leaks. "We need several weeks for some tests, that’s why the final report is expected after all the lab examinations are done and we have all the results," NCOC said. Despite the fact that no gas leaks were registered at the offshore gas pipelines or at the oil pipeline the consortium decided to make a full inspection of both types of pipelines to be 100% sure of the wholeness of the infrastructure before restarting the production at the field. At present time the pipelines at the Kashagan field are being emptied to be subsequently cleaned. The cleansing is scheduled to be completed in the first part of December. "All the necessary diagnostic equipment for internal pipe control is ready and will be running the diagnostics right after the pipelines are cleansed. The diagnostics consists of a number of runs through the pipeline using various inspection devices and accurate analyses and interpretation of the gathered data. Based on that a conclusion is going to be made," the representative of NCOC pointed out. The diagnostics of the inside part of the pipes is expected to reveal the extent of the gas pipelines damage and potential defects in oil pipeline. The final results of the data interpretation will be ready in the beginning of 2014. As an additional way to discover potential problems with the pipelines some excavations have been made at the most important sections of the oil and gas pipelines. No signs of leaks in the underwater sections of the pipelines, such as lowering of pressure, have been recorded. Although the excavation works are finished the results cannot be considered comprehensive or final. Discussion of adjustments and time required to make them, as well as the reliable forecast of the day the production will be resumed will be made only after the main causes of the defects and their scale are identified. Besides, the company said the dates of the production restart that were recently published in the media were only provisional. "We can announce the exact date only after the situation becomes clear and we coordinate it with the authorities,” the NCOC representatives said. The production at the giant oilfield started on September 11, 2013, but on September 24 it was suspended after a gas leak at the pipeline from Island D to Bolashak refinery was discovered. Consequently the defective junctions were replaced and the oil production from the field was resumed. But on October 9 the production was haltered again because another gas leak was found. When the repair of defective part was finished, a fully controlled hydro test was made. It revealed more potential leaks. The production was stopped and a thorough investigation was unleashed. By Azhar Ashirova

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