What is Offshore engineering?
Offshore Engineering is the engineering discipline that deals with the design and construction of structures intended to work in a stationary position in the ocean environment.
Examples of floating offshore structures are:
- Floating oil and gas production units, such as FPSO, semi-submersible platforms.
- Floating drilling units such as drilling ships and semi-submersible drilling platforms.
Examples of bottom founded offshore structure are:
- Jacket platforms
- Gravity based platforms
- Offshore wind turbines
Examples of subsea offshore structure are:
- Subsea infrastructure for oil and gas production such as manifolds, wellheads, flowlines
- Risers, umbilicals etc
There are hundreds of acronyms in offshore engineering literature and practice. Below is a list of the most frequently used acronyms. See also oil and gas acronyms and dredging acronyms.
|AHTS||Anchor Handling Tug Supply (vessel)|
|BFS||Bottom Founded Structures|
|BLS||Buoyant Leg Structures|
|BOE||Barrels of Oil Equivalent|
|BOPD||Barrels of Oil Per Day|
|BWPP||Drilling Wellhead Processing Platform|
|ERRV||Emergency Response and Rescue Vessel|
|ERRV||Emergency Rescue and Recovery Vessel|
|FOS||Floating Offshore Structure|
|FPF||Floading Production Facility|
|FPO||Floating Production Operation|
|FPS||Floating Production System|
|FPSO||Floating Production Storage and Offloading|
|FRU||Floating Regasification Unit|
|FSO||Floating Storage and Offloadiong|
|FSRU||Floating Storage and Regasification Vessel|
|GBS||Gravity Base Structures|
|GoM||Gulf of Mexico|
|HLCV||Heavy-Lift Crane Vessel|
|LWIV||Light Well Intervention|
|MODU||Mobile Offshore Drilling Unit|
|PLEM||PipeLine End Manifold|
|PSV||Platform Supply Vessel|
|SBM||Single Buoy Mooring|
|SPM||Single Point Mooring|
|SRV||Shuttle Regasifigation Vessel|
|SSCV||Semi-Submersible Crane Vessel|
|TBT||Tethered Buoyant Towers|
|TLP||Tension Leg Platform|
|TTR||Top Tension Riser|
1. Introduction to Dynamic Positioning
1.1. Dynamic Positioning Systems
For many offshore activities it is very important to keep a vessel at a fix position and heading. Dynamic Positioning (DP) systems automatically control the position and heading of a vessel by using thrusters that are constantly active and balance the environmental forces (wind, waves, current etc). Environmental forces tend to move the vessel off the desire position while the automatically controled thrust balances thoses forces and keeps the vessel in position.
The main components of any DP system are the positioning system, the DP computer and the thrusters. The positioning system, usually a GPS, monitors the position of the vessel. When the vessel moves off the intended position the DP computer will calculate the required thrust which will then be applying by the thrusters in order to maintain the position of the vessel.
1.2. The use of DP systems
Dynamic positioning systems are typically used by offshore vessels for accurate maneuvering, for maintaining a fixed position or for track keeping (pipe/cable laying). We usually find DP systems on:
- Offshore drilling vessels (Drilling ships and Semi-submersibles). A Drilling vessel will use DP to remain in a fix location while drilling in deep water.
- Offshore support vessels: Platform supply vessels (PSVs), Well intervention vessels, Diving Support Vessels. Support vessel use DP to stay in a safe distance from offshore platforms and drilling rigs.
- Pipe-laying and offshore construction vessels. Pipe-laying vessels use DP for position keeping and track keeping.
- Dredging vessels. Suction Hopper dredgers, Rock-dumping vessels, Trenching vessels
- Shuttle Tankers. Shuttle tankers during offloading of FPSOs.
The first DP system was set in use in 1961 ('Eureka'). Nowadays, there are over 1000 DP-capable vessels and DP is consider indispensable for deep-water operations.