- Welcome to the Core Description and Interpretation series for sandstone cores. My name's Ali Jaffri and I'll be leading you through this video series. I've been describing core, carbonates, siliciclastics, evaporites both conventional and unconventional for the past 11 years now, about three kilometers of core on a centimeter scale and I've picked up a few things which I would like to share with you. Today we're here at the USGS Core Facility in Denver, Colorado and the purpose of this tutorial is to focus on what you're supposed to do before you even start describing core. So I've got a few things here with me. First thing I've done is a log of the well that the core was taken from. This is very important. It's important because you want to be able to calibrate core with the log because there's always the depth shift and what I'm gonna do is I'm gonna go through this log, I'm gonna find thickest shield break, and then I'm gonna try to mash that up with what I have in my core and that's gonna help me figure out how off the core depth is with the measure depth that's in the log. Besides just a regular gamma ray, I've also brought this borehole image log. Again, it's very important because assumption is that most of the wells in your field are not gonna be core. So you're gonna have a lot more borehole image logs than you will core and if you can somehow calibrate your borehole image log with the core, it's gonna help you out a lot because then you can start reading electrophoresis and then you can start correlating electrophoresis. Besides the logs that I brought I've also brought some graphing paper. Now what you could do is you could potentially bring in a template that your company prefers using, whatever you're comfortable with. But I like to do it on my own graphing paper. I like to create my templates. In another tutorial, we're gonna go over how you can create one of these templates and I've got a clipboard that I'm gonna use. The next thing you'll need is a hands lens with a grain size chart. This is something I've been using for a very long time so this one is 16 times magnification and here's the grain size chart that goes with it. I've just clipped a little hole into it and I can put a shoestring through it and I'll just hoop this around my neck while I'm describing core. I have brought a scale separately. This is not for measuring, but this is for pictures. So any time I'm gonna take a picture, I'm gonna put the scale right next to it. You can also use a pen or pencil for scale. That also works, I just like to have a centimeter scale so it's a matter of personal preference. I also have this for measuring and everyone likes to do it differently. Some people prefer a ruler. I prefer this scale instead. I like this because what I can do with this is, see the clip on the back? It goes on my belt so wherever I walk I know I have this on me. I don't have to go around and look for my ruler because then you've got several boxes of cores. It's easy to lose your ruler so I keep this with me and these you can get fairly cheaply. Make sure you get one that has both a centimeter scale and feet or inches on it as well. Then I've got a notebook in which I can take notes because a lot of times you'll come here. You're supposed to describe a core, you open up a box and next thing you know it's just broken up fragments of rock. You can't even describe the core. So things like that you want to note in here. You want to make sure you document everything. Documentation is key because this lab happens to be 20 minutes away from where I live, but a lot of times I'm on consulting assignments, I'm overseas and I'm at a lab where I flew in for a few days, I'm gonna describe core, and then I'm gonna leave. And the last thing I want is to go back to the U.S., be sitting at my desk, and wishing I'd taken more notes. So you want to make sure you document everything. Going along with documentation is a camera. A lot of people these days they're using their cellphones, their smartphones to take photos. I prefer this and I'll tell you why I prefer this. Because most digital cameras actually have a Macro Mode. Okay, that's that little flower that you see. So let me put this on Macro Mode and show it to you. Alright, so if you can see it's on Macro Mode now. The Macro Mode is always represented by a small flower. Okay, so you can see it right there. Make sure you know how to use the Macro Mode on your camera. This is important whether you're describing carbonates or siliciclastics because what you will be doing is you'll be getting super close to the core and you'll be taking pictures of specific features so you want to make sure that you know how to use the Macro Mode on here. Now these are things that I've actually brought here with me. Most core labs will provide a spray bottle. Okay, so I've just got water in here. And besides the spray bottle, I also have a bucket. And what I'm going to do is as soon as I start opening these boxes up, you can see the boxes behind me, as soon as I start opening those up, I want to make sure I wash the core. I'm going to show you how to do that next, okay? So we're going to wash the core. The water that comes off of the washed core goes into the bucket. You don't want to wash the core while it's sitting in the box because it's gonna make a mess and you don't want to do that. Now some labs will supply a brush. I personally don't like to use the brush because a lot of times, especially with sandstones, the face is not very well-consolidated and if you use a harsh brush like that on the face, what you'll end up doing is plucking grains and we don't want to do that because if you start plucking grains off the surface of the core you're ruining its quality and if everyone decides to do the same thing in a few years, that core's gonna be worthless. Okay, so I avoid using that brush. Next step is opening these boxes and washing the core. Now one thing you should bear in mind is these boxes here are fairly easy to open. I'm gonna show you how to open these. This is because we're in a very well-organized, very clean lab here, but there are places in the world where you will show up at a core lab and boxes aren't as easy to open. I've been to core labs where the boxes were actually shut tight with nails so someone had to go in with a pair of pliers and chisels and hammers and it took about maybe two hours just to open up one core set. So do not assume that as soon as you go in you'll be able to start working right away. You'll want to set aside at least an hour for opening the boxes, arranging the core. A lot of boxes, the core sleeve is much wider than the core itself. As a result, when you move the core around it gets all jumbled up. So do spare about an hour just to open the boxes, organize the core, clean the core before you can even start describing.