Comparisons of the Driller’s Method and the Wait and Weight Method in Deepwater Well Killing Operation

With the rapid development of deepwater exploration, safety issues associated with deepwater well control have been highlighted in recent years. Due to the effect of large choke line friction losses and the narrow drilling window in the deepwater scenario, the risk of well control is higher, leading to an increase in the demand for a more desirable well killing method. The Driller’s Method and the Wait and Weight Method (W&W Method), both of which are the most widely used approaches in the well killing operation, have advantages and disadvantages. Therefore, the aim of this work was to present a quantitative analysis and provide a comparison between the two methods. The behavior of the drill pipe and choke pressures of the two methods was investigated by considering the influence of the choke line friction loss, gas expansion and circulation temperature. In order to evaluate their handling capacity in the deepwater well killing scenario, a mathematical model for kick tolerance and critical pit gain was developed. Moreover, a field case in the South China Sea, which has involved both the Driller’s Method and the W&W Method during construction, was applied to study the differences in the two methods in the view of field application. The results recommended that the W&W Method has an advantage over the Driller’s Method from the perspective of safety of the wellhead equipment and the handling capacity of the well kick, especially when the preparation ability of the killing mud is not strictly limited.