Offshore production

Offshore production presents many interesting corrosion problems. Platforms are built over the water and supported by beam piles driven into the ocean floor. Each beam is surrounded by a pipe casing for protection. Similar platforms are used far out at sea for radar towers. 

A variety of corrosion prevention methods are used in such structures, some of which are beyond the scope of this book. The corrosion prevention methods include  

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The function of offshore production facilities are very much the same as those described for land operations. An offshore production platform is rather like a gathering station hydrocarbons have to be collected, processed and evacuated for further treatment or storage. However, the design and layout of the offshore facilities are very different from those on land for the following reasons ... 

This section describes the main types of offshore production platform and satellite development facilities, as well as associated evacuation systems. 

Computer assisted operations (CAO) involves the use of computer technology to support operations, with functions ranging from collection of data using simple calculators and PCs to integrated computer networks for automatic operation of a field. In the extreme case CAO can be used for totally unmanned offshore production operations with remote... 

The ASME code requires every pressure vessel that can be blocked in to have a relief valve to alleviate pressure build up due to thermal expan sion of trapped gases or liquids. In addition, the American Petroleum Institute Recommended Practice (API RP) 14C, Analysis, Design, Installation and Testing of Basic Surface Safety Systems on Offshore Production Platforms, recommends that relief valves be installed at vari ous locations in the production system and API RP 520, Design and Installation of Pressure Relieving Systems in Refineries, recommends various conditions for sizing relief valves. 

This approach has been performed on. several offshore production facilities with inconsistent results. That is, items that were identified by one set of evaluators as required for protection in one design were not required by another set of evaluators in a completely similar design. In addition, potential failure of some safety devices on one facility caused evaluators to require additional safety devices as back-up, while the same group in evaluating a similar installation that did not have the initial safety devices at all did not identify the absence of the primary safety device as a hazard or require back-up safety devices. 

Based on the information contained in these figures it is possible to draw an area classification diagram of the facility. Figure 17-15 shows an example for a typical offshore production platform. 

Figure 17-15. Hazardous area location diogram for a typical offshore production platform.

RP 14F Recommended Practice for Design and Installation of Electrical Systems for Offshore Production Platforms RP. 500 Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified As Class I, Division 1 and Division 2. 

Vickers, K. and Knittel, T. no date. Detonation Arresters for Offshore Production Platforms. Paper presented to API Task Force for API RP I4C. Westecli Industrial Limited, Calgary, Alberta, Canada. 

FPN No. 5) For further information on electrical system for hazardous (classified) locations on offshore oil and gas platforms, see Design and Installation of Electrical Systems for Offshore Production Platforms, ANSl/APl RP 14F-1991. 

API Recommended Practice 14E, Fifth Edition Recommended Practice for Design and Installation of Offshore Production Platform Piping Systems, October 1991. 

In practical situations, if permeation through a hose lining, for example, is being considered, and the hose is exposed externally to a cold environment (such as the sea) while hot fluid passes through the hose (e.g., hot oil in the offshore production industry), a temperature gradient — Ti will apply across the lining. To cover this situation, for a representative permeation coefficient Campion and Thomas developed from Tick s laws... 

The application of a pillow (cap) gas containing air and oxygen, aimed at improving the gravitational segregation in offshore production technology, may offer an appropriate alternative to increase the recovery factor in heavy oil-bearing reservoirs [1052]. 

Primary separation facilities process the produced fluids and gases into individual streams of gas, oil and water. These facilities are commonly referred to as Gas Oil Separation Plants (GOSP s), Central Processing Facilities (CPF) or if located offshore on drilling, production and quarters platforms (PDQ s). The offshore platform may either float on the sea or be supported on steel or concrete supports secured to the ocean floor, where it is capable of resisting waves, wind, and in Arctic regions ice flows. In some instances surplus oil tankers have been converted into offshore production and storage facilities. 

The amount of explosion overpressure is determined by the flame speed of the explosion. Flame speed is a function of the turbulence created within the vapor cloud that is released and the level of fuel mixture within the combustible limits. Maximum flame velocities in test conditions are usually obtained in mixtures that contain slightly more fuel than is required for stoichiometric combustion. Turbulence is created by the confinement and congestion within the particular area. Modem open air explosion theories suggest that all onshore hydrocarbon process plants have enough congestion and confinement to produce vapor cloud explosions. Certainly confinement and congestion are available on most offshore production platforms to some degree. 

Offshore Egypt, Offshore Production Platform, Fire Ship collided with unmanned platform which ignited. 

Sometimes it is easiest to prepare a general flowchart that identifies events which may occur at a facility during an incident. This flowchart can identify possible avenues the event may lead to and the protection measures available to mitigate and protect the facility. It will also highlight deficiencies. The use of a flowchart helps the understanding of events by personal unfamiliar with petroleum risk and safety measures. It portrays a step by step scenarios that is easy to follow or explain. Preparation of in-depth risk probability analysis can also use the flowchart as the basis of the event trees or failure modes and effects. Figure 3 provides a generic example of a typical hydrocarbon process facility Safety Flowchart. API Recommended Practice RP 14C provides an example of a Safety Flowchart for an offshore production facility. 

American Petroleum Institute (API), RP 14C. Recommended Practice for Analysis. Design. Installation and Testing of Basic Surface Safety Systems for Offshore Production Platforms. Fourth Edition, API, Washington, D.C., 1986. 

American Petroleum Institute, (API), RP 14G. Recommended Practice for Fire Prevention and Control on Open Type Offshore Production Platforms. Third Edition, Washington D.C., 1993. 

The use of pads or other means of pipe attachment at support points should be considered for piping systems subject to wear and pipe wall metal loss from relative movement between the pipe and its supports (e.g., from wave action on offshore production applications). 

In the area of wind offshore energy, Garrad Hassan et al. (1995) place the electricity production potential at 10904 PJ/year including areas with a distance up to 30 km from the coast and a water depth of less than 40 m. The EWEA (2003) and Greenpeace (2001) apply further constraints leading to a significantly lower value for the offshore electricity potential (see Fig. 5.6). In this way they restrict the area available for offshore production to a water depth of 20 m and reduce the capacity density. 

SOFC. One SOFC project is to open up for offshore production of oil and gas without COj emissions to the atmosphere. Another activity is concentrated on improving the working efficiency and competitiveness of SOFC fuel cells for power generation with natural gas. The third R D activity on SOFC is related to filter mechanisms for cleaning hydrogen from gasified biomass to reach sufficient purity for use in an SOFC. 

The economic incentive to minimize fuel consumption on an offshore production platfom is, of course, influenced by the presence or absence of a market for gas, or other needs for gas, either initially or at some future date. In addition to the reduction or design fuel consumption to economically conserve resources, it may be economically worthwhile to consider designs which would consume less fuel at reduced producing loads. Many separation and compression systems consume fuel at essentially level rates, even at loads muck lower than design. 

The pipelines, which deliver natural gas from offshore production to the Absheron peninsula (at Zirya and one other point), where it enters the Baku region distribution system untreated. 

The breakdown of the investment cost for large-scale LNG plants may vary depending on the plant specification. A representative scope for a typical greenfield plant located to the Middle East for offshore production with an onshore LNG plant having two liquefaction trains shows that the LNG plant per se would account for roughly 50% of the total project, almost... 

Southern Alaska includes onshore and offshore production south of Artice Circle. 

Economics Variable production cost is dominated by feedstock pricing, especially for natural gas. The installed plant cost is the other main contributor to the total product cost. Total energy usage for a self-contained plant is typically around 7.8 Gcal/ton of methanol (31 MMBtu/ton) on an LHV basis. Capital investment varies tremendously with size and location however, a guideline installed cost for a 3,000-tpd plant is approximately U.S. 250-300 million. Synetix s LCM process offers improved economics over conventional processes. It is ideal for large capacities (over 3,000 tpd) where conventional plants cannot be used, such as, offshore production. 

American Petroleum Institute. 2007. API RP14E. Recommended practice for design and installation of offshore production platform piping systems. Washington, DC American Petroleum Institute. 

API Recommended Practice 14c (2001) Recommended practice for analysis, design, installation and testing of basic surface safety systems for offshore production platforms (American Petroleum Institute). 

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