B.A. Zoon and H.B. Bussemaker, HeereMac v.o.f., The Netherlands
Abstract
The exploitation of deep sea oil and gas fields in water depths ranging from 1000 to 3000 metres requires installation, repair, maintenance and removal of large and heavy (template) structures with masses up to 2000 tonnes. Review of the limits and boundary conditions on locating large and heavy units at the bottom of the sea has indicated that the most stringent problem is the vertical force required to perform these operations. This paper shows that the most promising way of delivering this force to the payload is by steel buoyancy bodies with gasses under the same pressure as the surrounding water. A concept is presented where these buoyancy bodies are combined into a so called Submerged Construction Resource (SCR), which serves as a platform to various deep-sea tasks. A specific advantage of the SCR is its relatively low steel construction weight, keeping investment costs far below alternative solutions. The SCR is connected with a few flexible lines from the surface vessel to control the installation process by providing passive vertical stiffness to the system. Preliminary calculations have shown that this way of delivering vertical force in deep water costs only one third of any competitive system. A SCR has the potential to be a simple, safe and easy to operate installation system.
MULTIPHASE PRODUCTION SYSTEMS R & D STATE OF THE ART
Ch. BRATU, Institut Fransais du Petrole
ABSTRACT
Studies and developments concerning multiphase production prompted a significant effort in R & D areas of pipeline flow behaviour, pumps, instrumentation and fluids (hydrates and paraffin deposition). Multiphase flow in pipelines network in steady and transient conditions is L still a basic goal; experimental correlations and computer W codes are now in validation phase using field data banks. Multiphase pumps groups development reaches the industrial phase; the rotodynamic pump (Poseidon) and the volumetric twin-screw booster (Novopignone, Bornemann) prototypes were recently tested on actual fields. Dedicated to F measure mixture flow rates, the instrumentation is still an uneven development. A lot of instruments are commercially ready, but their accuracy, stability, intrusive character or operational difficulties delay extensive field application. An important feature is related to the process of complex fluids in operational conditions that involves hydrates and paraffin deposit formation. Studies and experimental approach are focused on physico-chemical mechanism of deposit build-up pipeline multiphase flow configurations (including solid phase) and additives (dispersants, kinetic or combined).
