I worked at Unocal from 1989 to1992 and knew dozens of engineers involved with various drilling operations. I heard many interesting stories, but one was particularly scary about the biggest oil platform in Santa Barbara.
California crude oil is not the best oil for making fuel. Unlike the light sweet oil from Texas and the middle-east, California oil is known as being sour and heavy. This means that it takes more energy to produce the lighter fuels from the ‘heavy’ oil and the ‘sour’ label refers to the fact that it is high in sulfur. It is really difficult to make low sulfur diesel from California crude, but the bunker oil that cargo ships burn would be fairly easy to make and would produce a relatively large amount of sulfuric acid when burned. Along with the oil they would collect natural gas (methane) that was contaminated with large amounts of hydrogen sulfide.
So this was on the main oil platform off of Santa Barbara. I forget the name. Several things were done on the platform aside from collection of oil. They also pressurized the reservoir by pumping in sea water through injection wells (the people I knew never would admit that ‘natural seepage’ could be enhanced by water injection). They also separated the hydrogen sulfide gas from the methane they collected and pressurized it as a liquid in large tanks. There was enough hydrogen sulfide in the tanks at any one time to kill a couple of towns on the coast if it were released.
Hydrogen sulfide is the gas known for producing the smell of rotten eggs. At even very low concentrations it has a strong smell and is sometimes used as an odorant to warn of leaks. More commonly, though, they now use methyl mecaptan and other substances that are more effective at lower concentrations. All of them can produce anosmia, a condition where you no longer smell the substance after smelling it for a while. An additional problem with using hydrogen sulfide as an odorant is that at high concentrations you can’t smell it any more because it shuts off the sensors in your nose that detect it. This is slightly different than anosmia, because you never smell it in the first place. At these concentrations it is also toxic, and I don’t mean like where food contamination by trace pollutants is toxic. In this case you die fairly quickly.
The engineer that told the story was making the point that it was valuable to have oil professionals cross check each other. He was taken on the platform with a group of engineers to audit the safety measures on the platform. As they were being taken around and told to pay attention to what they were being shown he naturally focused on everything else he could see.
He saw that they were operating a crane and lifting girders up and across the deck. Each time the crane went across it went over some large tanks on the deck. He asked one of the tour guides what was in the tanks and they said, “that’s the hydrogen sulfide.” He asked if it was unwise to be lifting girders over the tanks repeatedly and they thought about it and said that he was right. They reworked their operations so that the girders did not have to go over the tanks. Perhaps the risk of dropping a girder was slight, but the consequences would be major. In fact, any mishap regarding those tanks could be major from a bad valve to a puncture or fire.
I spent 4 years going to school at UCSB before working at Unocal and never knew of the potential threat just off shore. The likely cause of the tar that was always washing up on shore I had already suspected. It was from natural seepage, potentially enhanced by salt-water injection. The tons of hydrogen sulfide? They never told us about it when I was a student. Then again what could they say… buy some duct tape? Any relatively small leaks would not be noticed on shore, and moderate leaks might be attributed to seaweed. You might imagine I was a bit concerned that they were thinking of selling some of the platforms to China.
I am all for taxing the oil production in California. They may cut production to use more light sweet crude instead but they will process the heavy sour oil eventually. Should we have more oil platforms off shore? I would say the fewer the better, and regular EPA and OSHA inspections for the ones we have would not be a bad idea either. We should also collect a dismantling fee so that when the oil companies are gone we can safely remove the miniature cities they have built offshore and deal with any blowouts that their well capping efforts are unsuccessful at preventing. Monitoring hydrogen sulfide leaks around oil operations makes sense now that companies like mine can detect small concentrations in real time