Research On Reliability Of The Ram Blowout Preventer

The Ram BOP (Blowout Preventer) is one of the most important equipment in the secondary well control equipment. The reliability of Ram BOP not only relates to the smooth and safe drilling operation, but also to extracting oil on time and ensuring the safety of operating personnel and equipment.The Ram BOP is so important in drilling, however, research focus on the reliability of Ram BOP is very little. So based on the Ram BOP produced by XinDe machine works as example, the physical design, manufacture, operation, failure mode and processing measure were found out by searching literature and site surveyBased on this, the structure of Ram BOP was decomposed firstly by mature reliability assessment methods at home and abroad. Every element was analyzed, and then the Ram BOP was divided to six subsystems according to their function and gat qualitative analysis result of elements included in every subsystem by FMECA. The subsystems and elements in FMECA analysis sheet were evaluated and quantized by expert scoring method, and the result was transformed to judge matrixes corresponding to every subsystem by using fuzzy comprehensive evaluation. So every subsystem was assessed by fuzzy comprehensive evaluation, and the matrixes that showed the safety degree of Ram BOP were transformed to reliability rate.During the process of fuzzy comprehensive evaluation, the subsystem that had low reliability was carried on separate evaluation and the weak part of the subsystem was found out. At last, one calculation soft was compiled by GUI module of MATLAB, and the whole fuzzy evaluation method was been realized.The research and calculation result indicates that the risk of seal system between ram shaft and sidedoor of the Ram BOP is largest. The risk of Y-sealing ring is largest in the second fuzzy evaluation and need further monitoring and protection.