An analytical parametric study of pipeline embedment into the seabed

ABSTRACT: Subsea pipelines are a very important part of extracting hydrocarbons from offshore developments. They are an effective way to transport extracted hydrocarbons from offshore platforms back to shore where they can be processed and distributed. When a pipeline is laid across the seabed, it can sink into the seabed by displacing or compacting the solid below it under the heavy weight of the steel pipe, concrete coating, and the pipe contents. Pipeline embedment is affected by the installation method, the weight of the pipeline, the movement of the sea around the pipe and pipe laying vessel, and the rate at which the pipe is laid. It is also important to consider that pipe can be embedded by both vertical and horizontal movement. Different combinations of horizontal and vertical movement can cause deeper embedment and more complex conditions. The addition of content inside of the pipe during a hydrotest or normal operation may also affect pipe embedment since the additional weight may cause the pipeline to sink more. This paper presents an analytical parametric study that examined the effect of some of the key factors affecting pipe embedment. Variables were changed one at a time while the other variables are kept at default values, and the effects on pipe embedment were monitored and analyzed. The study revealed several important trends. It was observed that several soil and pipe parameters affect the vertical force required for embedment in mostly linear patterns.