Abstract
A new Oil Country Tubular Goods (OCTG) Corrosion Resistant Material (CRA) 17-Chrome (17CR) was introduced in late 2011. The corrosion resistance performance of such material was claimed to be comparable to a higher grade material of duplex stainless steel 22-Chrome (22CR) under a given aggressive corrosion environment. In addition to that, 17CR was expected to be significantly competitive and commands shorter delivery lead time compared to 22CR as it does not require cold-drawing process to achieve the required high yield strength. PCSB had evaluated this new material for one of its massive LNG development projects through a series of qualification testing. These LNG carbonate fields were highly corrosive with CO2 and H2S content up to 22 mol% and 140ppm respectively. Maximum bottom hole temperature anticipated was more than 180 degrees Celsius. Material selection for production tubing was therefore of paramount importance in such severe well condition to ensure that long term well integrity was not compromised with this newly developed material. Through the establishment of a multidisciplinary team, PCSB had established a set of rigorous qualification test procedure, fully aligned with industry standards to ensure that the identified risks were mitigated from both material and connection perspectives. This paper will describe the systematic approach that was used to evaluate the reliability of the new material with a premium connection under the defined worst case conditions; discuss the corresponding results which led to significant cost savings for the mentioned project.
