This project presents the ways and means of the preliminary design of an FPSO to be installed in the AKPO field, offshore Nigeria with a close attention to its hull form. The design and modeling of a FPSO vessel is divided into two parts: one for the hull system and the other for the topside, but this study focuses on the hull form of the vessel. In other to achieve this, the principal dimension of the vessel is gotten through the use of linear regression to compare the dimensions of 10 similar vessels. Also the effects of the environmental loads which involves waves, wind and current on the vessel have been evaluated using the 100 years return period. The hydrodynamic motion roll, heave and pitch movement of the vessel was also analyzed . The different types of mooring system is also discussed in this study, although not included in the design
1.1 Background of the Study
A floating production storage and offloading vessel (FPSO) is a vessel employed by oil and gas companies to both process and store hydrocarbons in offshore fields. They are made up of two parts: the topside and the hull. The topside produces and off-loads crude oil and gas, and the hull, like a big tank, stores the produced oil. (John et al., 2009)
FPSO vessels, a transportable platform, are popular because they can be easily moved and installed to nearby platforms and also allow for easy transportation of oil to tankers or pipelines. Once an existing field has been depleted, FPSO can then be moved to other locations. This makes them suitable for smaller fields which can be depleted quickly and avoids the need for installing permanent expensive pipelines. The vessels often take the form of traditional tankers. In addition to dedicated vessels that are designed for FPSO, oil and gas tankers can be converted to an FPSO vessel which also makes them an economical and flexible option.
The vessels are moored in place either via a central weathervane or by spread mooring which involves the vessel being anchored via multiple points on the sea floor (Figure 1.1). This allows them to operate in both deep water and ultra-deep water environments which are designed to take into account local weather situations and can even be detached from moorings which make them ideal in extreme weather conditions (Terpstra, 2001).
The basic design of most FPSOs encompasses a ship-shaped vessel, with processing equipment, or topsides, aboard the vessel’s deck and hydrocarbon storage below in the double hull. After processing, an FPSO stores oil or gas before offloading periodically to shuttle tankers or transmitting processed petroleum via pipelines. However, the FPSO alone cannot produce oil and gas in the oil field. It requires many offshore production systems such as the SPS (Sub-sea Production Systems), UFR (Umbilicals, Flow lines, and Risers), mooring lines, a shuttle tanker, an off-loading buoy, etc. Thus, the design and construction of an FPSO includes many other offshore production systems.
1.2 Aim of the Study
The aim of this study is to carry out a preliminary design of an FPSO capable of withstanding its environmental conditions.
1.3 Objectives of the Study
The following objectives are to be considered in order to achieve the above stated aim;
Obtain the principal dimensions of the designed FPSO by regressing data of similar FPSOs.
Investigates the impact of environmental forces on the FPSO.
1.4 Statement of the Problem
Floating Production, Storage, and Offloading (FPSO) systems comprise a new branch in offshore technology in which new discoveries and innovations are being made constantly. Literature review conducted has shown that these new discoveries in technology are not being fully utilized. Also, FPSO design is very broad and requires the aid of experts on different fields.
I also learnt that oil companies (The intended customers of FPSO) are highly interested in improving the safety of the crew and environment, increasing the uptime and reducing the probability of oil spills. This, of course, is in addition to the main objective of reducing the costs and satisfying the production requirement.
1.5 Scope of Research
The preliminary design and modeling of a FPSO vessel involves the study of the following activities.
The principal dimension of the vessel through regression
Analyzing the environmental factors which include wind speed, wave depth and current speed
Hydrodynamic calculations involving the roll pitch and heave movement of the vessel.