You would think with that volume of gas you would be up there with a nuclear sized detonation
you could only detonate that gas if you managed to breach all of the holds, then bring in a very large tanker full of LOX, then vaporise both the liquefied gases (spilling them onto the sea wouldn't work too well - they'd crust it with ice and then run across the ice while the gas clouds disperse - you'll need to pump heat into the mix for a while), and then finally put the spark to the mix.
That's not impossible - but it's pretty hard to do.
If you're saying "detonate" when you mean "deflagrate", well that's a very different thing. The limitation of getting fuel and oxygen together becomes the limiting factor on the intensity of the fire that can happen. Didn't you cover this in your first week in employment, when you were doing your fire-fighting training? The old smoke-filled room? 4-man hose teams? Playing "find the valve" (hint : it's always behind the 30ft tall jet of flame)?
Actually, you may be shocked to learn, but people who design gas processing plants do go to considerable efforts to design out that sort of possibility. And, shockingly, the plants operators (who live and sleep on board) tend to be fairly cautious about, you know, blowing themselves up. Incidents do still happen (I had friends die on the Piper Alpha.)
Just as a start, there will be thousands (literally, not figuratively) of gas detectors all around the plant. And they'll be hooked into a detection system that, if gas is detected near tank 'P', for example, will re-route production into tank 'Q' ; start pumping the LPG from tank 'P' into another available tank (while flooding the head space in 'P' with exhaust fumes, to prevent entry of air), and alert maintenance techs (most of the 200 POB, Personnel On Board) to fault find and repair. Conceptually, the systems are not complex, but with hundreds of tanks (probably) and thousands of pipes and valves, the actual problem is quite complex.
If you'd RTFA, you may have noticed there is a "flare" built into the turret. The purpose of that is to be able to dump the process plant's contents into, in the event of a major system failure. It takes little time to shut wells in (a couple of minutes, depending on water depth), but the gas already in the lines need somewhere to go to. We call it "dumping the flammable inventory", and the safest way to do that is to burn the fucking stuff. There's a bloody good reason for that flare stack to be several hundred metres tall : when it is in use, it'll peel skin and paint at any shorter range.