When I started doodlebugging we had a 24-trace recorder and set patterns of 1/4# charges buried 3 ft underground. We were looking at reef formations about 3,000 - 4,000 ft. in MedMech's neigborhood. A string of 16 (I think) geophones were wired in parallel and one phone in series to balance the emf. The entire string of geophones would be laid and shot and then the line crew would pick up one trace and bring it forward up the line. On a good day we shot 2 miles. After processing the client would have a 2-d slice of the Earth's subsurface. When I left doodlebugging for good in 1983, GSI (the company that created Texas Instruments) was experimenting with 3-d seismic patterns using a 128 trace recorder. They were looking at a play around 18,000 ft.

Last week a seismologist came by (whom I didn't know) to talk about a prospect that would involve some input from where I work. During the course of discussion he indicated that he was shooting 3-d with THOUSANDS of traces. My jaw dropped at that and then he says he's recording down to a bit over 40,000 ft. That bowled me over and I frankly thought he was either lying (for some unknown reason) or pulling my leg. So I was pretty blunt.

He said, that they weren't looking to drill that deep but that his system was sufficient to get good records to that depth. He said he was getting about 80 ft resolution. He told me the actual depth that they were looking at and even that stopped me. I had no idea that technology had advanced so greatly as to drill so deeply. Also the surprising depth and accuracy of the seismic survey is freaking mind-boggling. So why run it out to 40,000? "Because we can and we don't want to have to re-shoot the prospect. Ever."

There are several former doodlebuggers around here and so I felt like this would be a great opportunity to make you feel old. I got out of the line of work because I thought seismic exploration was about done for. Wrong! Oh yeah, I also went broke!

I wonder if the result of the current high oil and gas prices will drive an exploration boom like the 1960's and 1970's. Couple that with the amazing seismic and drilling technology and we might end-up with another crude oil glut like from the 80's into the 90's. If so, that will happen in 5-10 years, IMO. But there's still the refinery bottleneck to hold prices high.

Make your play, podnuh.

B

Wow! I had no idea the technology had improve so much.

I was in up to about 1984, left the field because the companies were cutting back crews at a rapid pace, all because oil fell below $30 or $35 a barrel and exploration was quickly forsaken. At that price it wasn't economically feasible to hunt for oil deposits.

The shallow water crews I worked called it a good day when we would shoot about three miles. We probably used the same basic system you shoreside crews did, but we laid out a longer cable. I can remember reshooting lines several times because the client felt there was too much "noise" to be of any value. Shallow water and explosions don't mix too well, lord knows how bad we rattled the ecosystem, so I definitely agree with not having to reshoot.

With oil about to break through the $70 mark I am really surprised there hasn't been a major resurgence of doodlebug crews.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

This thought just hit me.

With the great leaps in technology I would have to imagine the crews could produce quality charts of the substrata, to reasonable depths (not 40K feet) using much smaller charges of gel and det cord. For the crews using air guns, well they could probably get great results out of single gun arrays rather than the triple gun arrays we developed.

We ran four triple arrays, which would literally shake the boat apart. The air blast would incapacitate fish (but not kill them) and really churned the sea bed in the shallows.

With so many traces and being able to chart so deep it appears to me that doodlebugging can be ecofriendly in the very near future.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

You are exactly right about eco-friendliness, especially as compared to our day of eco-trashing.

You're right that they use smaller charges but they use about the same intervals--220ft or so, IIRC. But they're using like 10# at about 50 ft. Also, the can offset a huge distance, he told me but I don't remember. When I surveyed 2-d lines 100 ft offset was a long way. This guys says they stack charges to undershoot sensitive areas and still get excellent records. I don't know enough about the seismograph end of things to understand all the stuff he was saying (talking to me like I knew a lot more than I know).

My interest in the depth and resolution of his records is in mapping the old Mississippi River distributaries. We know where they are from bore holes and such but getting seismic records from oil companies is like getting a rat from a terrier. I may get a shot at it after the client has drilled.

B

Interesting but, even with crude at $70/bbl, nobody's going to be routinely drilling to 40k feet for oil, at least not any time soon. There's too much out there that's easier to get, particularly in the GOM or west Africa

__________________
Never a dull moment at Berry Hill Farm.

That's right, given today's technology and oil prices.

40K is just a technological breakthrough or a oil embargo away.

Another result of the increase in resolution and computing power of the current seismic surveys over even the recent past is that old surveys can be re-evaluated with current computers to give better resolution of formations than what was computed only a few years ago and new shoots provide much higher resolution. This will result in discovery of sources that were previously overlooked or declined as ambiguous or too small, etc to develop. It may also give new life to old fields like in East TX where I heard there was a shoot going on in the Beaumont area (ever heard of Spindletop?) and Kilgore.

That's one of the problems of the "Peak Oil" estimations. They are always based on best guesses as to oil prices and technology. I think the "Peak Oil" theory is pretty much self-evident (it's a finite resource) but pinning down the date of "Peak Oil" is going to be done in hindsight, not in prediction.

B