The technology used for offshore oil and gas production has always needed to be flexible and fast-developing, in order to meet the wide range of challenges that different environments can present. Overall, the most important requirement of this technology has been a working deck which is mounted on a larger structure that provides enough space for all necessary production equipment, like processing facilities to separate oil, gas, and water, as well as pumps, compressors, connections, and living space for workers on the rig.
When platform development was not so advanced, the well drilling would usually be completed before the production process began, to ensure the safety of workers. Additional equipment and accommodation would also usually be located on a separate structure for the same reason. However, as wells were constructed in ever deeper water, new types of platforms needed to be designed.
Deep-water structures are very high-cost, and it is therefore more economically viable to accommodate workers and equipment on a single platform. Coupled with improved safety practices and fire prevention, this means that is now commonplace for offshore development to be situated on just one structure.
The most fundamental requirement for offshore drilling is a platform from which the whole operation can be run. In most cases, this is done from a fixed platform, but in recent decades floating production facilities have been successfully developed, and these are becoming increasingly common. These floating production units are the most commonly used when it comes to deep-sea applications.
With fixed platforms, there are two basic types, both with a subset of variations for specific purposes. These two types are piled structures and concrete gravity structures (Figure 1). Neither has gained precedence over the other, mainly because of frequent changes in the cost of materials, equipment, and specialized labor needed to construct them, as well as changing demands from the offshore industry as to the size of the platform.
Figure 1 – Piled Structure and Gravity Structure of Brent (Courtesy of Shell UK)
Each type has its own disadvantaged. Piled structures can be lengthy and costly to build, and during this period they are susceptible to damage from bad weather. They also lack oil storage capacity, and drilling and processing facilities and living space must be constructed only when the base structure has been fully completed. On the other hand, concrete gravity structures are more expensive to put together, and once the foundation has been put down, they are difficult to modify, meaning if the soil conditions change even slightly from those anticipated, there could be problems with the structure that are highly expensive to put right. In this article, it will describe basic details of piled offshore structure. Continue reading