If you think the deepwater horizon BP oil spill was an anomaly, you're wrong. Many rigs I've operated on have had the same shit happen.
Shitty Cement job: Check
The back up pod on the BOP is fucked: Check
The Company man doesn't want to lose 1-2 weeks of work at 1.2 million a day to fix the BOP cause the well is almost done: Check
The Company man down mans the rig after the cement job to save $$ on personnel: Check
The last well I drilled in Angola the company was loosing money and they wanted everyone off ASAP. They were rushing fast as fuck, so usually after a cement job they let it cure 12-24 hours before they slack off and let the weight of the riser (Sometimes a mile or more long of 36" steel pipe) rest on the well.
These CAC's said fuck it after 4 hours. So I'm monitoring the well and that bitch just disappears into the sea floor!! So they call me up and ask what happened and I'm like, bitch I don't know I'm not on drill floor. So in conclusion they have to pull the well up, the cement return valves had been snapped off and they ended up letting that shit cure for 48 hours cause they fucked up.

My overtime rate was about $1,200 a day so I didn't give a fuck. Matter of fact I would pick up on the average 10K extra a year due to the rig trying to rush jobs, fucking up and needing me to monitor their fuck ups subsea 24/7 until the rest of the crew could be called in.
So that's how the shit would work when working for American CAC clients. Try and save $250,000 and end up spending $2,000,000. Shit happens way more than you think.
On the same rig, we were drilling and they were losing thousands of gallons of oil based mud down the hole. No matter how they adjusted the weight they kept loosing it down hole. They thought they hit a cavity
Here is the MSDS for oil based mud, it's nasty shit!
http://redriversupply.us/usrfiles/msds/nov/NOV OBM Whole Mud MSDS.pdf
Anyway, a couple of months go by, we finished the well and it's my job to survey the well area to make sure we haven't "Disturbed" the environment. So I fly out about 50 meters from well center and I come across this giant fucking blob.
I call the company man to inform him that I think we found where all that mud went. He looked at the shit and said "It's a sea growth, it's nothing"

Well, I'd done my job and reported it to the person in charge. Nothing more I can do.
But the night company man saw it and said "Another shitty cement job huh? I said yeah, looks to me like Halliburton fucked up the ratio and the shit didn't harden, so when you were displacing the earth the mud was leaking up through the fissures.

Needless to say there are thousands of gallons of that shit on the sea bed that will probably last forever. I never saw crabs there, only eel so the seafood should be ok to eat there. I just would never fuck with the Octopus or Shrimp.
I went to another rig in Angola and they almost had a full blowout. See, nepotism runs deep in the oil industry. Combine that with incompetence and greed and you have a recipe for boom boom.
So usually there are 2 guys for most jobs in Angola.
1. An Expat who knows his shit 85% of the time
2. The Nephew of a government official that is his back up who just watch's and gets paid for doing nothing.
What's supposed to happen is you train the local guy and in 5 years he takes your spot. Most of the fuck up locals just want to sit for 5 years offshore and then join the shore base side and claim they are now an "Oilfield Engineer." It's a fucked up hustle for the regular local guys who want to do the job but get pushed out by the elite class.
Well, every once in a while, the Expat can't come to the rig. Visa issues, missed flights etc, so you have this useless fuck having to step up and do the actual job.
So they were in the control room, and the warning light kept blinking. So this genius decided to "fix" the problem.
His solution? Put tape over the blinking light.
Well, they are lucky cause there was an over pressure on the lines and the same jackass was going to try and shut it in. Somebody saw the gauges and rushed to vent the pressure. If they hadn't, the whole rig would have exploded. Oh, and the jackass that caused all the issues wasn't fired. They just moved him to another platform.
You don't hear about it, but people get crushed, killed, burned exploded and all types of shit on these platforms. At least 2-3 times a year, something like a small hammer, or big bolt or nut falls from the derrick and kills a person. something the weight of an ipad with enough velocity will smash through and hard had like it's not there.
I could go on man, I've seen and heard about so much fucked up shit it's downright frightening.