RE: Regarding lemons...16 Feb 2020 00:19
shedful,
"Though i wish you hadnt interchanged between metric and imperial. Though luckily or not i am of an age where i can occasionlay converse in both"
Sorry 'bout that!
But I was writing about sort of vague things. A 100x100x100 ft 'cube' of fractured basement is a pretty stupid sort of idea anyway, ,cos if you tried to cut a cube of such stuff out of a mountain on the Isle of Lewis, for example, it'd almost certainly fall apart, anyway, before you'd even managed such a task! (Thus partly proving my point.) And I just used metric for 'fracture width' because those were the units Mario used. And of course no fracture is a nice uniform 20cm wide, however you cut the cake.
For strictly oilfield calcs, I always (still) use imperial with some weird USA offshoots. Psi, feet, inches, bbl, etc. Give me depth of the hole (TVD) of a well that's taken a kick, drillpipe pressure when shut-in (in psi), mud density (in an arcane unit of 'pounds per gallon) in use, and within 30 seconds using a simple calculator like that on my phone, I can tell you by how much the mud weight should be increased to 'kill' the well. Tell me the size of your drillpipe (in inches, inside and outside diameter), inside diameter of the casing, plus depths (in feet), depth in feet of the open-hole section (inches), and within a few minutes (with the same calculator) I can give a total fluid volume in the hole within 0.5% accuracy. How about your mudpumps? Tell me the stroke length and liner size (again in inches), and I can tell you how many pump strokes it'll take to 'circulate out' the kick, even though that'll take a few more minutes). Of course there are tables or software which can give you such data, but in a race I could probably do it almost as quick. It's ingrained.
But the oilfield isn't the same the world over, and some horrible 'mismatches' often occur. For instance, in terms of pressure, other than psi, you've got bar, or kilopascals. Then, I have to start looking for conversion-tables. And volumes? Casing diameters measured in inches (still the industry norm), but depth in metres? OK, no big deal about the metres. Multiply by 3.281. I know that by heart. There are 6.29 bbl in a cubic metre. But hang on, no mudpump manufacturer sells a cylinder liner measured in centimetres: they're still in inches.
Going back to 'well-control'. Pressure relationship to depth is an important part of your calculations. But psi per metre? Literally, I've seen that!
OK, I'll stop blowing my own trumpet for a moment. But at least in oilwell drilling terms, metric is hopeless. A metre is too long a unit, a centimetre too short as a sub-multiple. You can't see a one-litre 'gas kick', but a cubic metre and you may already be in big trouble. And kiloPascals? Stupid.
Oh yeak, how do you measure drillpipe? Not in feet and inches, but feet and 'oilfield inches' which are 1/10th of a foot, and 1/10th of an 'inch'. 1/1oth of an oilfield inch is half a centimetre. More