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From Fossil To Fuel™
From Fossil To Fuel™

Episode 13 · 2 years ago

Episode 12 - Wireline and Logging

ABOUT THIS EPISODE

What is it and when do we use it?

My name is Brennan McDougall and I'm a professional engineer. Or the last decade I've worked in many different facets of the oil and gas industry. While I have a pretty solid technical background in oil and gas, I don't really know a whole lot about the other non technical departments that help run an oiling gas company. Recently I took a course to help develop my business acumen and better understand how the financial side of the business works. What a novel concept to educate the technical people on the business and financial side. I thought it would be a really cool idea to return the favor and educate the non technical people on the technical side. This is how the concept from fossil to fuel was born. Through these twenty four episodes, we will take a journey from how oil and gas was formed millions of years ago how it is refined into the fuel that runs our cars and heats our homes. Come join me on this adventure as we learn how the oil and gas industry operates from fossil to wire.

Lion is a primary piece of equipment used in almost all oil and gas operations at some point or another, and usually multiple times. When talking about wire line. You'll typically hear four different names tossed around slick line, braided line, wire line and electric line or Elne. Slick lines are single strand cables that are used to simply lower and retrieve equipment into the well, similar to how a bucket is lowered and retrieved from water wells, or at least how it was with water wells like a century ago. The slick line cable,...

...simply referred to as slick line, is spooled around a drum on the back of a special truck that has built in controls for running the slick line in and out of the well. Braided line is basically a multi strand slick line line. It's like taking a bunch of small ropes and twisting them together to make a bigger, stronger rope. Wire Line, which is the same as electric line or ELNE. It's both names can be used interchangeably, is a strand of multiple cables that are capable of delivering an electric current and or data to and from whatever tool or equipment it is attached to. Because of the ability to run power up and down the line, wire line has way more uses than slick line does, but comes at a higher price. Like slick line, it is also schooled on a drum and run on a very similar style of truck, but has added controls to be able to use all of the different functions enabled by Eline. Due to all the various functions of...

Wireline, it should not come as a surprise that it will be the focus of this discussion. So Eline, electric line, wireline, they're all the same thing, but going forward, to be consistent, we'll just call it wireline, meaning the type that can deliver an electrical current up and down the line. So before we get into details about the wireline equipment, let's take a look at all the different things that it can do. One of the main functions for wire line units is logging. Logs are a series of diagnostic tests that you can do on the rock formation to try and understand some of its properties. Log tools are run on the end of the wire line into the well to take continuous measurements as they go in and come out. This data is then transmitted up the wireline and recorded in the wireline truck where it can be further processed into a visual graphic or actually meaningful data. This data...

...will then enable the engineers and decisionmakers to decide on how they want to proceed based on the information that they're getting from the wireline logs. I should note that slick line can also deploy tools to perform data recording like this, but because the data can't be transmitted up the slick line, it has to be stored in the tool and then retrieved from the tool once it gets to surface and then processed after that. One of the most common tools other than logs is called the Gamma Ray tool. If you haven't heard of a Gamma Ray, it's like an x Ray, but stronger. Gamma Ray tools are able to measure gamma radiation from the formation rocks. Almost all rocks contain some sort of metal that gives off faint amounts of radiation. It's usually not nearly enough to harm a human being, which is why you never hear about it,...

...but it is there and we can record it. The Gamma Ray tool will have a sensor that can detect and record all of this naturally occurring gamma radiation. This data, like the logs that we talked about before, is transmitted up the wireline and processed in the wireline truck. As the wireline goes further down the well and is continuously recording the gamma radiation. The gamma signals will vary depending on what type of rock you're going by. The geologists are then able to compare the gamma signal from the wireline log with Gamma signals that they've previously identified and can figure out exactly what type of rock is where in the well. Because different types of rocks have signature gamma radiation signals, they're able to match these signatures on the log and identify the different layers of rock. The next type of tool is a nuclear tool and, rather than sensing radiation,...

...it actually emits radiation to collect information on the formation rock. The tool will contain a radiation source capable of emitting neutrons that are fired into the formation. Recall that earlier on we talked about perosity, which is the spaces inside the rocks, kind of like the holes inside a sponge, and this perosity is what's capable of storing oil and gas. Well, as you can imagine, the higher the perosity, generally speaking, the more oil and gas that will be stored. Since we're spending money to get oil and gas, higher perosity is generally a good thing. Nuclear tools will help us figure out what the perosity is. The radiation emitted will run into hydrogen atoms in the pores of the Rock. This interaction will actually create gamma rays that are released and then recorded by the sensors on the nuclear tool. The more gamma rays collected, the larger the number of interactions between hydrogen atoms in the poor spaces.

The higher the number of inner actions, the larger the poor spaces and therefore the higher the perosity. You can also use nuclear tools to measure the density of the Rock. The more dense the Rock, the more radiation it will absorb. Calculations can then be made based on how much radiation the sensors are getting back to figure out what the perosity and density are. It's great if you can figure out that your target rock has high perosity, but how do you figure out if it's oil or gas? A lot of the time it could just be water, which really isn't a value, or much value. That's where resistivity logs come in. resistivity is the resistance to flow of electrical current. If something conducts electricity very easily, like water, it isn't very resistive. These logs are able to identify water, boil and gas because of their different properties in conducting electricity. Most reservoirs will have water, oil and...

...gas. So not only can you figure out what you have, but you can figure out where it is, which makes it a lot easier when you're planning on where to go. Oil is lighter than water and gas is lighter than oil, so gas will usually be at the top of your formation, oil in the middle and water at the bottom. That is if you have all three resistivity logs will in eject electricity into the formation and, based on the resistivity at that point we'll be able to determine if it contains water, oil or gas. So let's recap. You've run gamma ray tools to figure out what kind of rock you have, you've run nuclear tools to figure out the density and if you have enough perosity, and you've run resistivity tools to figure out where the oil and gas is. What more do you want to know? Well, you can use sonic and ultrasonic tools to see what the...

...rock looks like. If you've ever seen an ultrasound on a pregnant mom, you know what I'm talking about. Not Too bad right? And that's just the tools that you can run on Wireline to evaluate the formation rock. There are also tools available to determine the quality of the cement behind your casing to make sure that there aren't any big gaps and that it's created a good seal. You can also get tools that figure out how deep you are by counting the individual pieces or joints of metal casing. Wireline can be used to run all kinds of completion equipment, like the plugs and guns we talked about when we were doing the plug and perf hydraulic fracturing. Let's talk a little bit about how it works. It's pretty simple, like lowering a pulling a bucket from a water well or lowering a lure from your fishing rod. You have to reel in or spool out the wire line as you come out or go in. The speeds are controlled by the operator. However, unlike a water...

...well, oil and gas wells are usually under pressure, so trying to run wire line into a well under pressure is like trying to put a straw in a shaken up bottle or can of coke and not spilling it. You need something to help keep the coat from spilling out while you put the Straw in. We run into the same issue with wireline. How do you get the wire line in the hole when the pressure in the well just wants to spit everything out? Turns out there's really two issues you need to address here. One keeping the oil and gas from spilling out, and to getting the wire line in the hole. Getting it in is easy. You just need to add enough weight to the tools on the bottom of the wire line so that the force of the weight of those tools going down is more than the force of the well trying to push it up. Keeping the oil and gas in the well while you do this is a little bit trickier. We do this using something called pressure control equipment. Without getting into too much detail, what...

...you're effectively doing is using a device called a lubricator that typically uses some form of grease to create a pressure barrier or seal around the wireline. If we use the coke bottle analogy, it's kind of like taking your hand and wrapping it around the top of the bottle. You can squeeze the Straw as you're pushing it in, just tight enough so you don't squish the straw, but squeezing it tight enough that you prevent anything from coming out as you push it in. The grease is doing the same thing as your hand. It is filling the void between the wire line and the inside of the lubricator so that no oil and gas can get by, therefore keeping everything in the well. The lubricator actually has a lot of little pieces to it, but we won't cover those in this episode today. Hey guys, if you like today's episode,...

...make sure you subscribe to the podcast. Unlike most podcasts that release an episode every week or two, I did all twenty four at once, Netflix style, so you can listen to them all right now if you just hit subscribe. If you like today's episode, make sure you leave me a comment or a thumbs up, or you can email me at from fossil to fuel at GMAILCOM, or look me up on Linkedin on Brendan McDougall.

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