Re: RE: paleonet Sieving of ditch cuttings samples

[Aidan Karley <aidan_karley@xxxxxxx>]

In article <E1CSiSK-00018g-00@newt.nhm.ac.uk>, Paleonet Digest wrote:
> I also deal with PDC cuttings.  Typically these cuttings have a =
> distinctive look which we call "ribbons" or "stack of coins". 
       Like a trilobite demonstrating it's gymnastic ability by doing a 
back-somersault. We call them "shavings", for obvious reasons. <DOH> - same 
shape (for the same reasons) as the shavings of metal from a drill-bit or 
milling machine - I remember finding that analogy when PDCs first became 
routine.

> I'll go =
> through and pick out chunks that don't look like they were cut by the =
> bit.  Distinguishing caved material by size probably wouldn't work well. =
> The size of PDC cuttings is affected a lot by rate of penetration, =
> weight on bit, lithology, and also by the size of the cutters on that =
> particular bit.  Some bits even have several sizes of cutters.
>
       Indeed. And if you're drilling sand, you'll get back mostly rock 
flour. A *lot* of my work is done geosteering horizontal wells in sandstone 
intervals, and on-site palynology is commonly a useful adjunct to (M|L)WD 
and lithology.

-- 
 Aidan Karley,
 Aberdeen, Scotland,
 Location: 57°10'11" N,  02°08'43"  W (sub-tropical Aberdeen), 0.021233