On Fri, 3 Jul 2009 09:31:33 -0700 (PDT), Gerry
wrote:

On Jul 3, 11:05*am, "David Courtney" wrote:
* * You could try going to a flooring/ceramic tile store and ask for some
scraps of granite, slate, marble, and limestone tile.
* * Use a 3" diamond hole saw to make disks that you could set at various
levels in your concrete cores?

"Gerry" wrote in message

...

I have a project for LSU to build a *reduced size oil drilling rig for
classroom use. Rig is made and has instrumentation to mimic the real
thing. Next phase is to make cores for it to drill through, simulating
different type and layers of formation. Been playing with parrifin and
cement combination but am looking for other ideas, like maybe some
epoxy/aggragate that will offer different drilling rates. Bit is a 1"
masonry bit, turning at speeds below 150 RPM. Cores are made up in 3"
PVC pipe with a 1/8 hole cast through the center to provide a flow
path for water to carry cuttings from hole. Any ideas for core
materials will be appreciated. Thus far I have used cement/sand with
varying levels of cement, and wax with bentonnite or sand. Both work
but I need more hardness to vary drilling rates

Thank you-all good suggestions. Because this is to be used in a
classroom and Profs are in a hurry to be able to show different
formations and their rate of progress I cannot go with materials that
are too hard to penetrate in a short time. Also, I am somewhat limited
to 50 to 75# weight on bit because all the top drive and carriage
weighs is 51#. Top drive is a 1/3hp gear motor controlled by a VFD.
Also the unit has a servo powered draw works to move the top drive up.
Feedback from the whole operation is fed back to a PC monitoring all
functions and controlling the draw works. Kinda of a neat toy and a
good leaning tool for future Petroleum Engineers when you don't have a
full scale drilling rig to play with.

I'm thinking fiberglass with sand as an aggragate may be worth playing
with. Perhaps with pieces of paver tile or slices of brick embeded in
the core as well. Maybe some ole pieces of transite siding if I can
still locate some.

Hardi Panel (hardi-plank, etc) has a consistency very similar to
transite - maybe a little softer.

Joe