Effects of Structural Parameters of Flow Tube on Flow Characteristics Near a Blowout Well

Abstract

Well blowouts are likely to cause fires and wellhead damage. The flow tube is a necessary device to raise the flame to reduce the temperature around the wellhead and provide suitable conditions to reset the wellhead device. The effect of flow tube structure and posture parameters on the flow field near the wellhead have been investigated and parameter optimization of the flow tube designing has been carried out. In this study, the well blowout jet interacting with the flow tube has been simulated using the most practical k-e turbulence model. We investigated the effects of the ratio of the inlet and outlet diameter ranges (1:1-2.4:1) and the length of the lower section ranges (1.5m-3m) on the distribution of the velocity and pressure of the two-section flow tube. The drainage effectiveness and flow control capability were analyzed. The effect of changes in height and angle on the forces affecting the flow tube during buckling-up-installation was examined. For evaluation purposes, the design parameters of the flow tube were optimized. For verification of model accuracy, the numerical simulation results were compared with the classical solution of the free jet. In the results section, it can be observed that the diameter ratio affects the inlet pressure, velocity, and entrainment of the flow tube. A strong negative pressure profile is witnessed in the straight flow tube and for every 12.5% increase in the diameter ratio, the negative pressure values at the inlet near the wall decrease by nearly 40% while the diameter ratio is increased by 12.5 percent approximately with the volume of entrainment diminished by 8%. When the diameter ratio of 2:1 is considered, the pressure at the center of the inlet changes from negative to positive. Therefore, we believe that increasing the diameter ratio can effectively reduce the negative pressure and entrainment volume. The length of the lower section also influences the inlet velocity and pressure distribution. With the increasing length of the lower section, the inlet velocity and entrainment decrease with a convergence profile. The results of the flow field when flow tubes inclined from 5° to 15° demonstrate that strong vortices are generated in the lower section. During this the overflow velocity increases by increasing the inclination angle. This study provides a better understanding of the mechanism of how the flow tube controls the jet flow and provides a theoretical foundation for the design of the flow tube. It concludes that the diameter ratio of the flow tube and the length of the lower section are the key parameters. It also provides a deeper insight into hazards near the wellhead, which can reduce operational risks for field operators.