Study on interaction characteristics between drill string and annular blowout preventer under emergency shut-in conditions

Abstract Under the condition of emergency shut-in, the rubber element of the annular blowout preventer (BOP) is impacted by the top drill string, which easily induces cracking, falling off, and other failure behaviors. Given the above problems, this study utilizes finite element theory to develop a simulation model of the annular BOP’s sealing behavior under drill string jacking conditions and analyzes the mechanical behavior of the rubber element. The results show that: ①Based on the tensile test data of rubber materials, the Yeoh rubber material constitutive model with the best fitting degree is obtained. ②The stress concentration regions of the rubber element are located at the inner interface of the rubber element with the support rib, the drill string-rubber element bottom inner surface contact zone, and the rubber element bottom-piston junction. ③The peak stress of the rubber element demonstrates a positive linear relationship with both the drill string’s upward velocity and friction coefficient, whereas it correlates negatively with the drill string’s diameter. The research results can provide theoretical support for the optimization of BOP emergency shut-in condition parameters.