Friday, April 23, 2010

Drilling Stories: Getting Started at Northumberland

Last fall I didn't make it out to the high country, or much of the low country, before the snow fell, so I've left off the sequential history-of-exploration posts. I'll jump ahead to something in the future of the Caliente-camp stories already told, and also in the future of other summer-of-1978-camp stories that are yet to come in that timeline. And so, to where and when should I jump?

Because I'm low on photos, I think I'll tele-transport to a time and place for which I have few photos. That is, I have a few old pictures of drill rigs and people from that time, but I don't have many, and I have fewer still that might be crucial to explaining the stories. And so it goes.

Once upon a time, I was assigned to my very first drilling project by way of being reassigned from a project I was already working on (another story entirely). I inherited this already-in-progress project in the middle of my second summer at Northern Exploration Company from another young geologist who was no longer working there. I inherited chip boards from about 10 conventional (non reverse-circulation) rotary drill holes. Possibly no core holes had been drilled at that time; possibly a few had, but if so, I don't remember them. I do remember, in immense detail, staring at the chip boards from those several already-drilled holes, studying them, comparing them to the down-the-hole electric logs and gamma ray logs, trying to glean as much info from them all as I could, trying to reconcile the chip boards to the formations I knew well from mapping those same formations the year before (mapping was done by myself and several others), and trying to come up with reasonable and good drill sites with which to continue drilling.

— NOTE: Chip boards were used prior to the invention of plastic chip trays. We spent our days, while out on the rig, gluing drill chips onto strips of plywood that were designed to hang in warehouses after logging was complete. We made the chip boards on the tailgate of my company Bronco; each plywood strip may have shown 100 to 400 feet of drill hole, depending upon the space reserved for each 5-foot interval. The photo to the right is a different kind of chip board, made from small pieces of material left from core drilling. A photo of a rotary-hole chip board can be seen here in Figure 1.

Why was I staring at the chip boards so intently? Was there a problem? One problem was that the chips going down the hole showed a gradational stratigraphy from the upper formation, the tuff of Hoodoo Canyon, through several well-defined and distinctive intracaldera units, to the lower formation, the Northumberland Tuff. On the ground, these formations were easily distinguished, one from the other, and though faulting proved to be a problem in correlating stratigraphy between some holes, the stratigraphy was fairly simple.

Another problem? I couldn't seem to get anyone to tell me much of anything about running a drilling program. "Think you can spend this $500,000 by the end of the year?" Well, who can say no to a question like that? Uh, when is the drilling scheduled to start? In the fall. Is there time to spend that much money? Yes, but not without getting several rigs. Can we get permits for road-building and drill sites by then, can we get roads and drill pads built by then, and how do you go about getting permitting and flagging roads? Yes, yes, and figure it out yourself.

The project was almost unimaginably large to me at the time. I had never before seen a drill rig, and didn't know exactly what I would be doing out there. I knew I should be concerned about the sampling, and understood from my graduate Exploration Geology course that there were several sampling intervals and procedures that I should probably choose between.

Aside: A rock hammer lost in 1978 could be in this photo (above). If you spot it, let me know. On the other hand, it could have been washed away in the flash flood of 1979.

Finally, one geologist—slightly older and a couple years more experienced than me—told me to sample on five foot intervals. That's a standard sampling interval for this kind of drilling program, but everyone else had left me guessing, and it had seemed like pulling teeth to glean this minuscule amount of information. Others probably thought the answer was obvious, contained in the chip boards of the earlier drill holes. What about sampling procedures, numbering systems, and size of bags to use?

"Oh, don't worry about it. The drillers will know what to do."

We had a name for this syndrome—the incomplete question answering and lack of explicit instructions—long before the end of the first year (the Caliente year). We called it, "Give them enough rope so they can hang themselves." The they that might get enough rope for hanging was us; those who might give us enough rope were our bosses. I didn't invent the name for this syndrome (the name being the quote) . The name was invented by the geologist who had the drilling project before me—Jay, I'll call him—a male geo, slightly younger than me, who had been on our 1978 crew from late Caliente to Deer Lodge and onward.

Problem two, the sampling interval: solved. What about problem one, the unlikely gradational stratigraphy?


Anonymous said...

Making those chip boards must have been loads of fun. There's a modern equivalent that uses compartmentalized sheets of adhesive paper (really sticky stuff, like carpet tape).


Some of my clients used to want these filled--a fiddly, time-consuming job if you do it right--in addition to the plastic vials.


Silver Fox said...

We had some way of making the things fairly quickly, and it's something you probably can't do outside if it happens to be raining - which it doesn't do that much in the summer/fall in Nevada.

Interesting about the sample file thingies you linked to. The chip boards can be hung up or leaned against walls, and holes can easily be compared visually. After some time, though, the chips might start falling off if they are used a lot, and putting HCl on the chips to see if they fizz kind of messes with the glue.