Drill pipes and Tool Joints Shearing Force Estimation in Blow out Preventers (BOP)s

Abstract

In the oil & gas industry BOP`s or Blow Out Preventers are the devices that are used to seal the well bore in an emergency situation and prevent the well bore fluids to reach the surface and cause damage. BOP`s consists of several stacks of preventers mounted on one over the other, the final defense is the shear ram, that shears the drill pipe or any tubular present in the well bore by passing through it completely. The manufacturers of the BOP`s use the basic equation of the “The Distortion Energy Theory” for the estimation of the shear forces of the tubular required for the shearing operation in case of activation of shear rams of the BOP`s . With the development of new technology and advancement of drill pipes materials, the basic equation i.e. the distortion energy theory (by using yield strength or tensile strength) would not be good enough to give an estimate of the shearing force .Failure of activation of shear rams would result in blowout accident, resulting in a great loss of life and property. In the current research, analysis and simulations are being done using FEM software DEFORM-3D .The analysis is carried out on the drill pipes, shear rams and varying pipe dimensions and applying different conditions to perform the simulations of the shearing operation when the shear rams would be operated. The results are compared with the theoretical calculations, experimental results and the shearing tubular data provided by the manufacturers of the BOP`s to know how accurately the DEFORM-3D results can provide the estimation of the shear forces of the drill pipes and additionally the tool joints also .Further analysis is done by considering actual well conditions applied to drill pipes, shear blade geometry effect , temperature ,kick conditions ,tool clearance and non-centralized string effects on the shearing force of the drill pipes.