Don't forget, an oil or gas production facility is different to a drilling rig. One lot floats, one lot doesn't.
A drilling rig is normally a jack up or semi submersible that is floated to a location and then either puts down its jack up legs or is tethered by buoys and anchors. You also have drilling ships that are held on station by thrusters and GPS. All these can "sink" and in several cases such as the semi-submersible platform, Alexander L. Kielland that capsized in high seas killing 123, or any one of the 30 or so major incidents involving the lost of 50 + people in each that we don't hear about because they were "brown people" operating in waters that we seem to just not care about
A production installation such as Piper A is fixed to the sea bed by permanent legs. These can't sink (by theory).
All platorms have passive and active fire detection and fighting systems onboard that are normally set to be automatic. The design of platforms means that only the minimum number of personnel are in a dangerous area at any one time. The Temporary refuges and Accommodation block are heavily protected by deluge systems.
The HSE has very clear guidance for the operators, which is that personnel come before assets...but due to the very nature of the dangers involved, without an asset, you don't have personnel.
There was an incident that I was personally involved in that happened in 1986 in Brunei, on a DSV.
I was in saturation, and we were on a two-man bell run when one of the generators in the engine room caught fire.
The fire was put out, but all power was lost and we were in no danger of sinking.
I don't know how the bell was recovered to the surface and mated to the chambers, but it was done. There was no point me worrying about it because it was all out of my control, I was only a passenger.
Once we were in the living chambers an emergency decompression was initiated and we decompressed in about 48 hours as opposed to a normal deco which from the depth we were stored at would have been roughly 96 hours.