Currently, Indonesia have a lot of offshore platforms. Most of them are fixed platform. These main structures can be divided into 3 parts :
The lower part of main structure will act as covered layer of pile and support upper deck. As you see the image, they may have a lot of braces and other structural support such as can, barge bumper, skirt pile guide and mudmat framing.
A Tubular pipe that made of steel will penetrate into seabed through jacket till certain depth below the mudline. Pile consist of main part, stabbing guide, cutoff, transition piece and skirt.
The upper part of oil platform consist of single or multi module. These module will be supported by main and additional framing through main or cellar or mezanine deck.
Structure installation would be done after load out activity is completed. Installation using lifting method has more benefit than float over method as it will save time and manpower. However additional studies have to conducted before any method can be used to install the module.