Finite element analysis of deepwater conductor bearing capacity to analyze the subsea wellhead stability with consideration of contact interface models between pile and soil

Bearing capacity of deep-water conductor belongs to the research category of pile soil mutual interaction, which indicated that reasonable pile soil contact interface model is of great significance to calculate the bearing capacity correctly. In this paper, theoretical models have been established to calculate the lateral displacement and vertical bearing capacity. Two different pile and soil contact interface models are taken into consideration to calculate conductor lateral displacement and vertical bearing capacity using ABAQUS software by writing corresponding computer programs of constitutive model of interface model. The two different models calculating lateral displacement are contact mechanics model and contact element model. The two different models calculating vertical bearing capacity are coulomb friction model and Goodman element contact model. The results show that the lateral displacement calculated with the contact element method is greater than that calculated with contact mechanics model. However, the vertical bearing capacity calculated by Goodman model is greater than that calculated by the coulomb friction model. Moreover, the variation of vertical bearing capacity with jetted depth calculated by theoretical model, coulomb friction model and Goodman element contact model are different with one another. The variation of conductor lateral displacement with wellhead load and the variation of conductor vertical maximum bearing capacity with conductor size have also been figured out. In order to improve the subsea wellhead stability, the suggestion is calculating conductor bearing capacity with different contact models between pile and soil and take the minimum value as conductor design bases. The method introduced in this paper has a significant reference value to analyze the safety of subsea wellhead.