海洋工程手册

Handbook of Offshore Engineering S. Chakrabarti (Ed.) C 2005 Elsevier Ltd. All rights resened 1 Chapter 1 Historical Development of Offshore Structures Subrata Chakrabarti Offshore Structuve Analysis, Inc., Plainfield, IL, USA John Halkyard Technip, Houston, TX, USA Cuneyt Capanoglu I.D.E.A.S., Inc., Sun Fyancisco, CA, USA 1.1 Introduction The offshore industry requires continued development of new technologies in order to produce oil in regions, which are inaccessible to exploit with the existing technologies. Sometimes, the cost of production with the existing know-how makes it unattractive. With the depletion of onshore and offshore shallow water reserves, the exploration and production of oil in deep water has become a challenge to the offshore industry. Offshore exploration and production of minerals is advancing into deeper waters at a fast pace. Many deepwater structures have already been installed worldwide. New oi1,'gas fields are being discovered in ultra-deep water. Many of these fields are small and their eco- nomic development is a challenge today to the offshore engineers. This has initiated the development of new structures and concepts. Many of these structures are unique in many respects and their efficient and economic design and installation are a challenge to the offshore community. This will be discussed in more detail in Chapter 2. In order to meet the need for offshore exploration and production of oiligas, a new generation of bottom- supported and floating structures is being developed. The purpose of this chapter is to introduce the historical development of offshore structures in the exploration of petroleum reservoirs below the seafloor. The chapter covers both the earlier offshore structures that have been installed in shallow and intermediate water depths and the various concepts suitable for deep-water dev- elopment as well as those proposed as ultra-deep water structures. A short description of these structures is given and their applications are discussed. 2 Chapter I 1.1.1 Definition of Offshore Structures An offshore structure has no fixed access to dry land and may be required to stay in position in all weather conditions. Offshore structures may be fixed to the seabed or may be floating. Floating structures may be moored to the seabed, dynamically positioned by thrusters or may be allowed to drift freely. The engineering of structures that are mainly used for the transportation of goods and people, or for construction, such as marine and commercial ships, multi-service vessels (MSVs) and heavy-lift crane vessels (HLCVs) used to support field development operations as well as barges and tugs are not discussed in detail in this book. While the majority of offshore structures support the exploration and production of oil and gas, other major structures, e.g. for harnessing power from the sea, offshore bases, offshore airports are also coming into existence. The design of these struc- tures uses the same principles as covered in this book. however they are not explicitly included herein. We focus primarily on the structures used for the production, storage and offloading of hydrocarbons and to a lesser extent on those used for exploration. 1.1.2 Historical Development The offshore exploration of oil and gas dates back to the nineteenth century. The first offshore oil wells were drilled from extended piers into the waters of Pacific Ocean, offshore Summerlands, California in the 1890s (and offshore Baku, Azerbaijan in the Caspian Sea). However, the birth of the offshore industry is commonly considered as in 1947 when Kerr-McGee completed the first successful offshore well in the Gulf of Mexico in 15 ft (4.6 m) of water off Louisiana Burleson, 19991. The drilling derrick and draw works were supported on a 38 ft by 71 ft (1 1.6 m by 21.6 m) wooden decked platform built on 16 24-in. (61-cm) pilings driven to a depth of 104 ft (31.7 m). Since the installation of this first platform in the Gulf of Mexico over 50 years ago, the offshore industry has seen many innovative structures, fixed and floating, placed in progressively deeper waters and in more challenging and hostile environments. By 1975, the water depth extended to 475 ft (144 m). Within the next three years the water depth dramatically leapt twofold with the installation of COGNAC platform that was made up of three separate structures, one set on top of another, in 1025 ft (312 m). COGNAC held the world record for water depth for a fixed structure from 1978 until 1991. Five fixed structures were built in water depths greater than 1000 ft (328 m) in the 1990s. The deepest one of these is the Shell Bullwinkle platform in 1353 ft (412 m) installed in 1991. The progression of fixed structures into deeper waters upto 1988 is shown in fig. 1.1. Since 1947, more than 10,000 offshore platforms of various types and sizes have been constructed and installed worldwide. As of 1995, 30% of the worlds production of crude came from off