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My old man did this work in the Navy (on P-3s) on 'pure science' missions and later on Twin Otters looking for oil. As I understand it they look for slight vari

My old man did this work in the Navy (on P-3s) on 'pure science' missions and later on Twin Otters looking for oil. As I understand it they look for slight variations in gravitational pull that represent different densities in the crust of the Earth. The S/N is so bad that even with current computers they couldn't do the analysis on the aircraft. They would have to beam the data to Boston where a room full of computers tackled it. The main problem the oil industry faces is the density of oil is similar to the density of salt. The only way to tell one from the other is to drill an insanely expensive exploratory well. My dad said half the time they hit salt. Really expensive salt.

mblakele 16y ago
Interesting stuff. I think M.A. Foster used this as a plot device in "Gameplayers of Zan".
jarek 16y ago
I'm not a geologist either, and apologies if I screw something up in the explanation, but: My geologist (-in-training) friend tells me that you would actually look for the salt because a geological process/property often causes oil to be found around salt domes. Salt is less dense than rock around it, so in terms of geological time it will tend to get pushed up relatively fast. As it goes up, it will bend up the layers of rock around it, breaking the lower ones as it goes through them and deforming the ones above. Salt itself is practically impermeable, and so are some layers of rock. Oil, which is fairly light, will flow up and collect in pockets formed against the edge of the salt dome where a layer of impermeable rock has been bent up. In http://faculty.ksu.edu.sa/alhomadhi/Evaporates/Oil%20Traps%20Around%20Salt%20Dome.jpg http://faculty.ksu.edu.sa/alhomadhi/Evaporates/Oil%20Traps%2... the pink layer is mostly impermeable, the grey-brown layer is porous and therefore permeable. Oil is trapped against the salt dome in the pockets created by the dome itself. I understand not every salt dome will have oil around it, but there's only one way to find out. I don't think exploratory wells are that expensive, but of course they aren't exactly cheap either. However, drilling around the domes will still get you better chances than just drilling blindly.
- mbenjaminsmith 16y ago
  I think you're right about salt domes and oil. I'm probably wrong about the densities as well. Everything I know was what I picked up from my (non-geologist) father over beers. I don't think it's the drilling itself as much as it is the in/accessibility of the site. They were usually doing surveys in the Andes or the Amazon river basin. Not exactly friendly territory. They lost two crews while in South America. Mountains, bad weather and an expensive/tight schedule are a bad combination. He said they could never know where they went down, so they would watch the villages to see where airplane parts hit the markets. Pretty sad stuff.
  - stcredzero 16y ago
    I wonder if this is an area where drone aircraft would be useful?
    - jarek 16y ago
      Likely. This is subject to the usual caveats that come into play when dealing with drone aircraft: availability of technology and cost. In particular, I doubt it would have been feasible to do this with drones back when mbenjaminsmith's father was working on this (or at least I got the impression this was a fair while ago). And even now, since the primary users of the technology are still military and other government agencies, it's not exactly cheap. Depending on how the company values a life and what are the estimates of risk, it might not happen for a while.
      - stcredzero 16y ago
        I suspect that the economics will play out much like ROV submersibles. Over the long term, operating and insurance costs will be much less for the drones.

mblakele 16y ago

Interesting stuff. I think M.A. Foster used this as a plot device in "Gameplayers of Zan".

jarek 16y ago

I'm not a geologist either, and apologies if I screw something up in the explanation, but: My geologist (-in-training) friend tells me that you would actually look for the salt because a geological process/property often causes oil to be found around salt domes. Salt is less dense than rock around it, so in terms of geological time it will tend to get pushed up relatively fast. As it goes up, it will bend up the layers of rock around it, breaking the lower ones as it goes through them and deforming the ones above. Salt itself is practically impermeable, and so are some layers of rock. Oil, which is fairly light, will flow up and collect in pockets formed against the edge of the salt dome where a layer of impermeable rock has been bent up. In http://faculty.ksu.edu.sa/alhomadhi/Evaporates/Oil%20Traps%20Around%20Salt%20Dome.jpg http://faculty.ksu.edu.sa/alhomadhi/Evaporates/Oil%20Traps%2... the pink layer is mostly impermeable, the grey-brown layer is porous and therefore permeable. Oil is trapped against the salt dome in the pockets created by the dome itself. I understand not every salt dome will have oil around it, but there's only one way to find out. I don't think exploratory wells are that expensive, but of course they aren't exactly cheap either. However, drilling around the domes will still get you better chances than just drilling blindly.

mbenjaminsmith 16y ago
I think you're right about salt domes and oil. I'm probably wrong about the densities as well. Everything I know was what I picked up from my (non-geologist) father over beers. I don't think it's the drilling itself as much as it is the in/accessibility of the site. They were usually doing surveys in the Andes or the Amazon river basin. Not exactly friendly territory. They lost two crews while in South America. Mountains, bad weather and an expensive/tight schedule are a bad combination. He said they could never know where they went down, so they would watch the villages to see where airplane parts hit the markets. Pretty sad stuff.
- stcredzero 16y ago
  I wonder if this is an area where drone aircraft would be useful?
  - jarek 16y ago
    Likely. This is subject to the usual caveats that come into play when dealing with drone aircraft: availability of technology and cost. In particular, I doubt it would have been feasible to do this with drones back when mbenjaminsmith's father was working on this (or at least I got the impression this was a fair while ago). And even now, since the primary users of the technology are still military and other government agencies, it's not exactly cheap. Depending on how the company values a life and what are the estimates of risk, it might not happen for a while.
    - stcredzero 16y ago
      I suspect that the economics will play out much like ROV submersibles. Over the long term, operating and insurance costs will be much less for the drones.