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Permalink Reply by Les Bamburg on June 4, 2009 at 11:51

Mac, please see the following:

http://en.wikipedia.org/wiki/Core_sample

http://homepage.ntlworld.com/leslie.foster/core_drilling.htm

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Permalink Reply by Checkmateking on June 4, 2009 at 12:10

I have a Haynesville core, pretty neat.

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Permalink Reply by BirdDawg, plain ole' idiot on June 4, 2009 at 13:42

My grandfather was a driller from the 1920's thru the 1960's and he saved many of the cores they took early in his career. They were 3" to 4" in diameter and some of them are amazing. Some of the cores I have are from what he called "oil shales" (probably fairly shallow). And they are full of very distinct fossils.

Now they take "side wall cores" from every sand well they drill. I have no idea what they are doing in the shale. But the sidewall cores are small and cylindrical, obtained from tools that utilize guns to shoot them into the formation prior to setting casing. These cores are usually sent immediately to labratories that analyze the content of each core for their content of oil, gas and water, and also to determine the porosity and permiability of the formations. This information, in combination with the e-logs of the well, determine the possibility of production, whether or not to set production casing, and the exact areas to perforate.

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Permalink Reply by Les Bamburg on June 4, 2009 at 15:03

BirdDawg, in my past I knew we always shot sidewall cores on the Gulf of Mexico wells for information. Occasionally we would attempt to take a full core but it generally failed due to unconsolidated nature of offshore sandstone formations ("beach sand").

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Permalink Reply by Mac Davis on June 4, 2009 at 15:12

Thanks for the info. Apparently, you can fetch multiple side cores with one pass by withdrawing the drill pipe and sampling multiple places along the hole.

The things I'm talking about were too big for side cores. They'd have to be whole cores.

Whole coring seems to be a process where you have to pull the pipe up, remove the drilling bit, put in a coring tool, drop the pipe, create the core, pull it up to remove the coring tool and core, put the drilling bit on, drop the pipe, and then resume drilling.

i.e. you have to pull the pipe up twice and lower it twice for one whole core. One would think they'd do this as infrequently as possible, especially in a deep well.

By the way, what is a "sand well?" A well into an oil or gas bearing sand formation?

My recollection from back then was that these things were everywhere, in the thousands or tens of thousands. If they really were from wells, they had to be something that you made dozens of per well. Maybe somebody used well cores for lawn decoration, people liked it, and someone started making lookalikes from concrete. Maybe concrete cylinders were just the rage for decorating lawns at that time. Maybe they were test samples from batches of concrete at the local cement plants. Maybe leftovers from some other industrial process.

They really did look like concrete. I wonder if maybe they were made somehow in the casing process? e.g. You pump concrete down the well to make the casing, and the concrete hardens somewhat in the pipe before you pull it up. You then have to push the concrete out of the pipe, and you end up with a lot of waste concrete cylinders the size of the inner bore of the pipe and the length of one section of pipe.

BirdDawg, your cores sound like the right size. They would definitely be interesting to see. How long were they? Did they vary much in length? The things I remember seemed to be all the same length.

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Permalink Reply by alleyboy on June 5, 2009 at 12:22

I remember what you are talkinig about because I used some of them for flower bed borders.
this was back in the fifties.
These were sampes of concrete that they poured and tested to makE Sure the concrete thay were going to use for constructing highways etc. met specifications. Thus they were just concrete samples. I've seen thousandfs of them in piles at concrete pouring facilities and they ssaid come and get 'em
for free. This was in the late forties and early fifties. They were simply called (*core ssmples)

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Permalink Reply by Mac Davis on June 5, 2009 at 16:13

Thanks. It only took me 45 years or so to figure out what they were. Hey, you accept things uncritically as a kid.

Strangely enough, I was driving around today and saw where someone had used them as "don't drive off the edge of the culvert" barriers in their driveway. I stopped and got a closer look and a picture. They were apparently concrete and did not look like anything that had been drilled out of something larger, so you're probably right.

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Permalink Reply by The_Baron on June 10, 2009 at 10:03

We still take core samples. not every time but a lot. At the bare minimum we will take sidewall cores as they are cheaper.

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Permalink Reply by Mac Davis on June 10, 2009 at 12:55

You mean "whole" cores? Does that involve pulling up the pipe string, inserting a coring bit, then pulling it back up and going back to a drilling bit? Sounds expensive.

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Permalink Reply by Mac Davis on June 10, 2009 at 18:42

I've got no emotional attachment to this. Just wondering if they ever do whole cores.

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Permalink Reply by The_Baron on June 11, 2009 at 3:24

First a disclosure. I am not involved in HA wells.

But yes, we prefer to take Whole Cores. We like to see the rock column, not just the snapshots you get when you take sidewalls.

And yes, it can be expensive, you have to pull out of the hole, change to a coring bit, go back in, core (which can be slow), and come back out with the sample, change bits, then go back in, ream the hole, and drill to TD.

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Permalink Reply by Les Bamburg on June 11, 2009 at 3:40

Baron, plus for Haynesville Shale wells - it means backing up the hole to kick-off for the lateral.

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