SCIENTIFIC BASIS OF DEVELOPMENT AND THE METHODOLOGY OF CREATION OF STEELS FOR THE PRODUCTION OF OILFIELD CASING AND TUBULAR GOODS WITH THE INCREASED STRENGTH AND CORROSION RESISTANCE

The authors carried out the survey of the crashworthiness of the oil-field and transportation equipment and noted the significant (by times, and sometimes dozens of times) exceeding of the allowable reliability index of the pipeline systems according to the values of the specific failure rate (item/km/year). It is shown that the main reason for pipe degradation and fracture is the internal corrosion which, depending on the composition of produced fluids, is manifested by one predominant type or the combination of several types of stress-corrosion fracture: hydrogen cracking, sulfide stress corrosion cracking, carbon dioxide, sulfide, and bacterial corrosion. Based on the generalization and systematization of the results of numerous research and applied works on the development and utilization of new pipe steels with the increased strength and corrosion resistance, the main scientific ideas of the formation of steel corrosion resistance in the highly aggressive oil-field fluids are proposed. The authors developed the methodology and offered the sequence of measures (algorithm) to solve set problems on the development of steels for production of oil pipes with higher mechanical properties and the resistance to stress-corrosion fracture. A list of necessary research, tests, and requirements to the product quality is defined. The authors proved the rationality of used approaches, methods, and decisions on the alloying, microalloying, modifying, and selection of the structural condition of the developed steels and on the technology of pipe production. The paper presents the examples of the development of new steels with the increased strength and corrosion resistance and, consequently, for the efficient solution of issues of the improvement of the performance characteristics of oil-and-gas pipeline and oil-well tubes.