The paper investigates hydrodynamical aspects of a 2- body, floating offshore production system for benign environments. The main focus is on the following issues:
Comparison of multiple body and single body hydrodynamical coefficients.
Mesh size requirements, computer run times and convergence of multiple body computations. The overall importance of the hydrodynamical interaction for the motion response of the two bodies is discussed in some detail, and it is documented how neglect of the fluid coupling effect may lead to erroneous and some times unconservative predictions.
Over the past decade the offshore industry has put much effort into reducing development and operating costs, in order to improve profit margins and to become less vulnerable to fluctuating oil prices. As a whole this drive has forced the industry to become more innovative and more alert to alternative technical solutions. This could imply more attention given to subsea production, but also increased emphasize on optimal surface production facilities. The 2-body system investigated in the present paper is a partial response to the latter concern, being a reasonably cost efficient and flexible solution for mild environments. The basic idea is to have a small size, unmanned TLP as the only permanent installation. This well head platform does have drilling capabilities, but needs assistance by a tender vessel (in the present case a barge) during periods of drilling and workover. During these intervals the two structures are moored in a tandem arrangement, where the separate mooring systems of the two structures are supplemented by a "soft" connection to avoid excessive contact forces, while at the same time maintaining full operational availability. A general outline of the system is presented in Fig. 1, while more specific information can be obtained from Table 1.
