Analytical Modeling of Well-Conductor Seabed Interaction in Complex Layered Soil in Newfoundland Offshore

ABSTRACT: This paper presents an analytical study of the well-conductor in complexly layered soil by providing a theoretical basis for the stability of wellhead. Arbitrary seabed soil stratum from Newfoundland deep offshore was considered, where the seabed sediments have distinct layers with varying properties and thickness which has a certain effect on the lateral loading capacity of the casing string. Considering the lateral loads on the top of the casing string, variable stiffness of casing string and the geomechanical characteristics of the soil layers, the differential equation of casing deflection and its solutions were established below the mudline, and the results of the modal analysis were obtained. The study revealed the importance of soil layers with different stiffness on the peak bending moment and deflection of the conductor system. The influence is more significant in the shallower layers closer to the sea bottom. It was observed that an in-depth knowledge about the geological data of the layered soil is of paramount importance for the accurate design of the conductor and surface casing. The analytical approach was found an appropriate system for early assessment of conductor system performance in layered soil condition.