Improvement of the SSC resistance of high strength steels for drillcollar through composition optimization

摘要

During drilling operations, depending on the location of the oil reservoir, componentsrnof the bottom hole assembly may be exposed to sour environments and mayrntherefore suffer from sulfide stress cracking (SSC), a form of cracking assisted byrnhydrogen embrittlement, that occurs in H2S containing environment. Steels of thernAISI 4100 series have long been used for the manufacture of SSC resistant drillingrncomponents such as drill collar or tool-joint. Their excellent resistance to SSC isrnattributed to their tempered martensite microstructure as well as their alloying withrnmolybdenum and vanadium. With the development of deep drilling, there is anrnincreasing demand for steels grades having higher SSC resistance, that couldrntherefore be used at higher stresses. For drill collars in particular, it is sometimesrndifficult to meet the market requirements using existing standard grades. The aim ofrnthe work presented in this paper is therefore to improve the in-service properties of arnsteel grade for drill collar by composition optimization.