Influence of drill cuttings on the installation of offshore infrastructure

Drill cuttings are a by-product of drilling operations associated with oil & gas exploration and development, and their presence on the seafloor can increase uncertainty associated with installation and performance of offshore infrastructure. Although two-layer profiles have been investigated for a range of boundary value problems, there are few that consider drill cuttings, such that their influence is still unclear. This paper addresses this uncertainty through centrifuge modelling of both uncemented and cemented cuttings recovered from an offshore location field. Simplified shallow foundation models were used to investigate the penetration resistance, squeezability and sliding resistance in uncemented cuttings, while a separate pile model was used to investigate cemented cutting-pile interaction. Results demonstrate that while penetration resistance through uncemented cuttings is negligible, their presence may increase resistance in the original seabed. Further, while uncemented cuttings may ‘squeeze out’ through drainage holes during installation, a portion is likely to be trapped beneath (and within) the foundation, which may impact interface sliding resistance during operation. In contrast, the presence of cemented cuttings may increase (shallow) penetration resistance by more than 2 times under the conditions examined in this study, while observed boulder movement and breakage provide possible explanations for some of the sudden drops in resistance.