A Blowout Preventer (BOP) consists of several sets of shear rams stacked together out of which Blind Shear Rams (BSR) is a very critical component to achieve complete shearing of drill pipe. The current study focusses on developing a methodology to model the shearing process and validate it with the shop test. Shop tests were conducted to shear a drill pipe using a surface BOP to obtain the maximum shearing force, shape of sheared drill pipes, shearing time etc. The shear rams used in the test are laser scanned and used in FEA simulations. The FEA model is developed such that it replicates the shop test and simulations are performed using Abaqus Explicit finite element solver. The output from simulations and shop test are compared and found to be in good agreement. The developed methodology is further verified by applying it for shearing different drill pipe sizes and the output is compared with the available data and found to be comparative which proves that the methodology can be implemented for various shearing studies.
Original Equipment Manufacturer (OEM) formulas are currently being used in industry to compute the maximum shearing force required to shear the drill pipe under various scenarios. The OEM shearing force is computed for the model under consideration and compared with the shop test and simulation and is found to be conservative. The validated model can be used for conducting studies that provide information on the governing parameters in terms of loading or positioning of the drill pipe to be considered in shear ram designs. This study provides a tool for optimizing the preliminary design of new shear rams and can contribute to more reliable and efficient shear ram design. The study is conducted as part of a Technology Assessment Programs (TAP) for the Bureau of Safety and Environmental Enforcement (BSEE) in the areas of BOP stack sequencing, monitoring and kick detection.