A Study on Dynamic Response and Stability of Conductor Pipe in Shallow-Water Field

Abstract

Maintaining the vertical position of the conductor pipe during drilling and nondrilling operations remains a challenge in shallow-water fields. In Tianjin’s shallow-water field, a conductor pipe left for evacuation was found displaced on resumption for drilling operation. This prompts the need to address the problem by investigating the stability of the conductor pipe and to prevent its future occurrence. In this work, a governing equation is presented to study the mechanical behavior of a conductor pipe in a shallow-water field under the combined effect of soil, waves, current, and wind. The displacement response equation of the conductor pipe was solved numerically from which other responses were obtained. Various influencing factors such as internal fluid, top weight, and wall thickness are analyzed for the conductor pipe. Modal analysis carried out shows that the part of the conductor pipe in soil tends to vibrate for higher modes, thus threatening the stability of the conductor. Results show that significant displacement occurs for the conductor part in water, which indicates that the combination of waves and current on the conductor prevails over the top free-boundary condition effect. Analysis results also show that drilling mud of higher density in a conductor with applied top weight on it improves the stability of the conductor. The results have been validated using abaqus simulation.