Study On Dynamics Of Process Of Subsea Suspended Cluster Manifold Entering The Water

The subsea manifold is the key transportation equipment in the subsea production system,because it can provide a gathering point for subsea oil and gas from subsea trees.it can also provide the distribution point for the water injection,gas injection,chemicals injection,etc.Meanwhile,it has many advantages in optimizing the subsea production facility layout,reducing the number of pipelines.The traditional subsea manifold is a large-scale subsea equipment based on subsea infrastructure in seabed.Although it has been widely used in the development of subsea oil and gas fields,it is not easy to dispose,recycle and reuse,and it has higher requirements on the seabed topography.A new generation of subsea production system based on subsea suspended cluster manifold was born.Based on t the certain sea conditions in the South China Sea,this paper carries out the dynamic analysis of the process of entering water of 3000 m subsea suspended manifold in order to provide theoretical support and technical methods for the practical engineering application of the installation of 3000 m subsea suspended cluster manifold.This paper combines a sea condition of a certain sea area in the South China Sea with a water depth of 3000 m,the installation capacity of domestic existing vessel resources in China,and a decentralized installation process,and proposes a set of 3000 m subsea suspended manifold fiber cable decentralized installation and recovery process flow.Considering that the center of gravity of single-layer buoy is above and below the sea level,the mathematical model of water inflow into the cabin is derived respectively,and the time required to fill the whole buoy with the specified weight is calculated.At the same time,the simulation of single-layer buoy with the center of gravity below the sea level is performed by Fluent,and the accuracy of the simulation results is verified by comparing with the theoretical calculation results.The multi-body lowering system model of installation vessel fiber cable subsea suspended manifold is established in Orca Flex,and the stress of fiber cable and the motion response of subsea suspended manifold are studied in the process of entering water.The influence of different factors such as wind speed,wave height and lowering speed on the installation process of subsea suspended manifold is simulated and analyzed by using the method of control variables.The results and suggestions can provide some reference and guidance for the practical engineering application in the future.