Challenges Faced by The Offshore Structures

Offshore Engineering is that branch of Engineering that deals with the designing and construction of the structures amidst the oceans. These structures are to be in stationary position and must be able to resist the extreme weather conditions in an Ocean Environment. The atmosphere that these structures experience differs variedly than the normal structures.

They tend to experience large wind loads with high wind speeds and the wave loads of the ocean bodies, ice – bergs, seismic loads. Majority of these structures are built for Oil and Gas Platforms.

The main aspects to be considered during the study of designing and construction of these Offshore Structures are:

• Site Survey
• Geological Conditions
• Environmental conditions
• Materials that could be used
• Maritime Challenges that encounter

‘Stochastic’ defined as the random distribution that is analysed statistically but cannot be predicted precisely. Stochastic Modelling aims at estimating the probable outcomes within a forecast to predict conditions for different situations. Modelling involves mathematical models for non-deterministic physical systems that tends to adapt to multiple behaviour. For instance, Monte Carlo Simulations analyse the different complex probability systems through random sampling of the initial conditions.

Stochastic Computer Simulations evidences the evolution of variables that vary randomly with probabilities. With these simulations, it is possible for us create a project based on the random values.

In the traditional method to determine return period, various long-term dynamic environmental conditions of disasters that are statistically analysed, and the dynamic parameters corresponding to different return n are selected and used for design standards.

For instance, the 50-year wave height, 50-year wind speed and 50-year current speed may be adopted as design criteria. At present, to design offshore platforms, especially platforms in the Bohai Sea, return period is always determined with a 50-year return period, which is arbitrary and lacking in reasonable basis.

However, different extreme marine environmental conditions occurring simultaneously is a small probability event, which, if used as design criteria, is inconsistent with the actual environmental conditions, that makes the probability significance unclear, and causes the calculated reliability of the structure to be quite different from the actual situation.

Higher values of design parameters always lead to larger design structures and higher investment, which even results in lost exploitation value of marginal oil field. Determining properly the joint return periods of marine environment conditions is very important for the safety of offshore structures and brings in lower investment.

Oceans and Seas account to more than 2/3rd of the size of the Earth. Because of which, the Oil and Gas Platforms has taken a leap from conventional rigs to huge reserves where the minerals exist. And due to the advantages at the marine environment, offshore construction has been booming day by day.

The construction of Oil drills on land was very complex and thus became more demanding for their construction offshore. However, the offshore constructions were till complex and expensive and on the other hand, was one of the most hazardous constructions.

The engineers involved in such type of work had to be provided with supply ships and helicopters to make the work much easier in terms of movement and costs.

With high waves, winds and extreme weather conditions, enough cushion must be provided against the Marine environment’s hazardous conditions.

Some of the challenges faced are listed below:

• Complex Working Environment – Tedious working machines and tools are used for greater depths. Machines and tools running to a surface depth of up to 1800 feet is likely to pose many weaknesses making it vulnerable to Earthquakes and intense waves resulting in high risks.
• Harsh Weather Conditions -It is literally too hard to govern the surrounding environmental conditions which only keep worsening the effects on the equipment’s and the engineers working. When the structures are constructed to withstand the Castro tropes, these harsh weather conditions minimise and reduce the functionality ability.
• Limited Access to Safety Points - By all the standards, these structures remain to be dangerous. Majority of the risks depend on the type of the surrounding environment. From combustible elements to moving cranes, the tendency of an accident/ explosions to arise becomes unstoppable.
• Increased pressure during construction/ installation - Most of the drilling/ installation work takes place beyond 2000 feet and the pressure developed at this depth leads to face an extreme challenge gradually. At that depth, the drilling equipment needs to strong and much heavier emanating the mud or control systems and causing large spillage the marine bodies.
• Fires - Most dangerous. Structures being located far from the coast, becomes hard to escape an explosions or other sudden hazards in case of spontaneous fires.
• Hydrocarbon Leaks – Between the year 2012 and 2013, among the recorded reports of the Hydrocarbon leaks, 27% of such instances were recorded. In a liquid state, they cause slippery problem and in case of a gaseous form a leak, they cause severe respiratory problems and sometimes can also result in further ignitions or explosions.
• Fatigue – Long distances result in long working hours and sometimes 7 – 14 days for a team, this thereby reduces the performance. Also, results in exhaustion risk of the accident rate. Most common example of fatigue risks are materials falls and spills.
• Limited Communication Network – Most essential in any field. And during offshore construction, the communication and their network become the utmost important criteria as machines that requires signals for performance slows down the activities. This worsens the situations when the engineers cannot reach out to the back-end team in case of emergencies.
• Confined Working Stations – Limiting the space required for the designing is the major concern resulting in a drawback.