Development and Field Test of Novel Expandable Surface Conductor in Deepwater Oil and Gas Wells

Abstract

Summary Jetting of surface conductor installation has become a popular method in the offshore oil and gas industry. However, wellhead sinking, tilting, and other instability problems still exist due to the insufficient bearing capacity of the conductor, resulting in substantial economic losses. Based on the traditional installation process, a novel expandable surface conductor technology is put forward, which can effectively increase the surface area of the conductor, change the bearing capacity mechanism between the conductor and the surrounding soil, strengthen the bearing capacity of the conductor, and reduce the risk of wellhead instability, which is an economical, safe, and efficient method. First, the delayed expansion material in water was evaluated and selected, and the volume change of expansion material with time under different temperatures and pressures was measured by laboratory experiment. The calculation model has been established for the ultimate bearing capacity of the expandable surface conductor considering the volume expansion effect, and experiments of field application have also been performed in the 1500-m water depth area. The application practice shows that the theoretical predictions are consistent with the actual situation. Using the novel expandable surface conductor, the surface area of the surface conductor can be increased by more than 15% and the bearing capacity can be increased by more than 20%. The expandable surface conductor can meet the requirements of field construction, reduce the setting depth and number of surface conductors, and can significantly increase the bearing capacity of subsea wellheads, thus providing technical support for increasing the efficiency of deepwater drilling while reducing costs.