Subsea

Subsea is a general term frequently used to refer to equipment, technology, and methods employed to explore, drill, and develop oil and gas fields that exist below the ocean floors. This may be in "shallow" or "deepwater".

Deepwater is a term often used to refer to subsea projects located in water depths greater than 1,000 feet, and may include floating drill vessels, semi-sub rigs or Semi-submersible Platforms.

"Shallow" or shelf" is used for shallower depths and can include standing Jackup Rigs or similar.

Background and history

Oil and gas fields reside in deep water and shallow water around the world. When they are under water and tapped into for the hydrocarbon production, these are generically called subsea wells, fields, projects, development, or other similar terms.

The first subsea well was in one of the Great Lakes in the USA and was in only a few feet of water.

Systems

Subsea production systems can range in complexity from a single satellite well with a flowline linked to a fixed platform, FPSO or an onshore installation, to several wells on a template or clustered around a manifold, and transferring to a fixed or floating facility, or directly to an onshore installation.

Subsea production systems can be used to develop reservoirs, or parts of reservoirs, which require drilling of the wells from more than one location. Deep water conditions, or even ultradeep water conditions, can also inherently dictate development of a field by means of a subsea production system, since traditional surface facilities such as on a steel-piled jacket, might be either technically unfeasible or uneconomical due to the water depth.

The development of subsea oil and gas fields requires specialized equipment. The equipment must be reliable enough to safe guard the environment, and make the exploitation of the subsea hydrocarbons economically feasible. The deployment of such equipment requires specialized and expensive vessels, which need to be equipped with diving equipment for relatively shallow equipment work (i.e. a few hundred feet water depth maximum), and robotic equipment for deeper water depths. Any requirement to repair or intervene with installed subsea equipment is thus normally very expensive. This type of expense can result in economic failure of the subsea development.

Subsea technology in offshore oil and gas production is a highly-specialized field of application with particular demands on engineering and simulation. Most of the new oil fields are located in deepwater and are generally referred to as deepwater systems. Development of these fields sets strict requirements for verification of the various systems’ functions and their compliance with current requirements and specifications. This is because of the high costs and time involved in changing a pre-existing system due to the specialized vessels with advanced onboard equipment. A full scale test (System Integration Test – SIT) does not provide satisfactory verification of deepwater systems because the test, for practical reasons, cannot be performed under conditions identical to those under which the system will later operate. The oil industry has therefore adopted modern data technology as a tool for virtual testing of deepwater systems that enables detection of costly faults at an early phase of the project. By using modern simulation tools models of deepwater systems can be set up and used to verify the system's functions, and dynamic properties, against various requirements specifications. This includes the model-based development of innovative high-tech plants and system solutions for the exploitation and production of energy resources in an environmentally-friendly way as well as the analysis and evaluation of the dynamic behavior of components and systems used for the production and distribution of oil and gas. Another part is the real-time virtual test of systems for subsea production, subsea drilling, supply above sea level, seismography, subsea construction equipment and subsea process measurement and control equipment.

Remotely Operated Vehicles



Remotely Operated Vehicles (ROV's) are robotic pieces of equipment operated from afar to perform tasks on the sea floor. ROV's are available in a wide variety of function capabilities and complexities from simple "eyeball" camera devices, to multi-appendage machines that require multiple operators to operate or "fly" the equipment.

Organizations

A number of professional societies and trade bodies are involved with the subsea industry around the world. Such groups include Subsea UK, Society of Petroleum Engineers (SPE), American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), National Association of Corrosion Engineers (Nace).

Government agencies administer regulations in their territorial waters around the world. Examples of such government agencies are the Minerals Management Service (MMS, US), Norwegian Petroleum Directorate (NPD, Norway), and Health & Safety Executive (HSE, UK). The MMS administers the mineral resources in the US (using Code of Federal Regulations (CFR)) and provides management of the country's hydrocarbon resources.

Safety

Subsea hydrocarbon (oil and gas) extraction has an exceptionally safe record and has been going on for approximately 100 years.

From http://en.wikipedia.org/