Although 3D seismic imaging, based on surface sources and receivers, has been the primary tool used for geophysical reservoir monitoring to date, vertical seismic profiling (VSP) has characteristics that make this technique particularly suitable for time-lapse surveying. In particular, the use of downhole receivers provides some advantages:
The subsea manifold as the hub oil and gas transportation equipment is a critical part for the layout optimization of subsea production system and reducing the number of pipelines. The traditional subsea manifold is fixed on seabed by its foundation, so traditional manifold system is hard to be discarded and recovered although it has many advantages and is applied widely in the deep water development scenario. In this paper, a new subsea suspended manifold concept is proposed to discuss its feasibility by the hydrodynamic performance state in vertical tension and catenary mooring methods. A mathematical model is established to solve the chain tension distribution and displacement of the subsea suspended manifold. Meanwhile, the motion response of the subsea suspended manifold under different influence factors, tension distribution of the mooring chains and the flexible jumpers in two mooring schemes are simulated, respectively, through OrcaFlex software. The research results will provide an important reference for the optimization of the preliminary scenario design of the subsea suspended manifold mooring system.
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AbstractHybrid risers rely on axial tension, generated by a combination of aircan and distributed buoyancy, to control their static deflection and dynamic response. In deep water, the base tension required to achieve an acceptable response can be significant (70-1000Te). This tension must be reliably reacted into the seabed over the life of the development. Depending on the configuration of the selected foundation there may be, in addition to axial tension, bending moments, shear loads and loads arising from flexure of rigid base jumper spools. The result is a complex set of load conditions, which, when combined with installation issues, can lead to a foundation system that is a significant cost element in the overall riser system. A number of foundation designs have been proposed and used for free standing risers however, the selection and design process is often not clear. This paper presents a review of the potential design solutions depending on water depth and design loads and outlines approaches adopted on existing projects. The key design and installation drivers are discussed, allowing improved understanding of the issues and the impact on the global riser design and installation strategy. The paper also discusses issues and implications of extending free standing risers to ultra deep water, which often have soft seabed conditions, further compounding the foundation design process.
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