Lesson 1.01 Unconventional Reservoirs Introduction

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01. EOR for Unconventional Reservoirs - Lesson 1.01: Introduction

Hi, my name's Todd Hoffman, and I'm teaching a course at SAGA Wisdom on Enhanced Oil Recovery in Unconventional Reservoirs.
Now, my experience in unconventional EOR goes all the way back to 2006/2007, when I first started teaching at Montana Tech. Back then, the unconventional revolution was just getting started. And there was a field in Eastern Montana, the Elm Coulee field, which is kind of the Montana Bakken you could think of, that had been producing for a few years since about 2000. But even in those six years or so, you could tell that EOR was going to be needed. The rates dropped off quickly and recovery factors were really low. We had a student who did a summer internship for one of the operating companies out there in the Elm Coulee field and he came back and he was excited. He wanted to do his master's work on enhanced oil recovery. And that's kind of where I got started, but it tied in nicely with my kind of background in conventional EOR. I had kind of spent my early years working steam floods in California, the Kern River and the Bell Ridge Dynamite's. And then later I'd done a little bit of work with CO₂ floods, more modeling work in Wyoming and West Texas. So it really attracted me to this problem that our industry was facing, which is how are we going to get more oil out of these reservoirs, these unconventional reservoirs? So after the Montana Bakken, we worked a little bit on the North Dakota side. Did quite a few projects in the Bakken in North Dakota. Eventually moved into the Eagle Ford, worked some in the Niobrara and most recently kind of looking at the Permian and some EOR that might need to be applied there.
What I'm hoping you get out of this course, basically kind of four things. One, just a broad overview of kind of where things are happening, what's happening, and a little bit about the technical advances that are happening that allow us to apply EOR to unconventional reservoirs. Two, we really want to look at some of the tools that we have available to us to do things like estimate oil rates, injection rates, kind of at a very early stage, kind of the scoping stage part when they're kind of back of an envelope type calculations. So we'll look at some of those things. Also just kind of look at what's happened in the field studies. There's been a lot of work that's happened in these fields. And I've kind of followed along a lot of these, what's happening with companies. And so we'll talk quite a bit about that. And then we'll wrap up looking at kind of if you are looking to implement an the EOR project in your unconventional field, what are some things you need to think about? What are some operational aspects, some non-technical things that you need to consider? How do you prepare for that first pilot, that first gas you're going to inject or first fluid that you're going to put into the reservoir? And so that's kind of the quick overview of what's in the class. I hope you enjoy it.

02. What is in this course?

Now some information about the course, kind of what we're going to go through. So beginning of the course, we'll just kind of talk about some background information stuff, kind of, what are unconventional reservoirs, what's EOR? Make sure that we're all kind of on the same page.
And then a big part of the class we'll talk about what's happened so far? What have people done in the field? What have companies done in the field as far as EOR in unconventionals and kind of the lessons learned and things that we can pick up from that and take forward as we go forward.
But kind of the big part of this class, I'd say the meat of the class is really about Huff-n-Puff gas injection. Really, most of the work that's been done is in there. We'll talk about how it's done, kind of the mechanisms, understanding the physical processes. We'll go through some fairly simple analytical tools that we can use to better understand, better design our projects as we're kind of looking on going forward.
And then we'll also, we won't just focus on that, we'll also talk a little bit about water, surfactants, other EOR techniques, maybe some thermal EOR for unconventional reservoirs.
And then at the end, we'll really talk about the practical aspects of EOR in unconventionals. So what are some operational things we need to think about? We'll look at what information we need, what kind of labs we'd like to do. How to build models, if we're going to do some flow simulation modeling, how we do that. And just kind of the lessons learned again from the operational aspects of the course. So that's kind of just the outline of the course.

03. Unconventional Reservoirs - What?

I do want to talk, as I mentioned, just a little bit about what are unconventional reservoirs. And I know most people taking this class, they probably have a pretty good idea. But because unconventional reservoirs is a pretty vague term, we might like to just talk a little bit about it. And people call it different things. Like you'll hear them called shale oil reservoirs quite a bit. There's some problems with that, they're not all shales, We hear them called source rock reservoirs. Again, that's a term. Or liquid-rich reservoirs or tight light oil. So there's a bunch of different names for these types of reservoirs. But just so that we're all clear, kind of my definition of unconventional reservoir, it really starts with the permeability.
So these are extremely low permeability reservoirs. These are micro and nanodarcy permeabilities. And really the source rock is either the same rock that we're exploiting or very close to that. And that's kind of the structure part of it.
Then the other part, I think what defines an unconventional reservoir, is how they're developed. So really, because the permeability so low, we need to do hydraulic fracturing. Because there tend to be thinner zones, we usually do long horizontal wells. So the combination of these long horizontal wells, multi-stage hydraulic fracturing in low permeability reservoirs is really how I think we define or how I define unconventionals reservoirs. And for this class, that's kind of the definition that we're going to use. So that's kind of what unconventional reservoirs are.

04. Unconventional Reservoirs - Where?

Where are conventional reservoirs? Well, because again, they're kind of the source rocks of all the conventional reservoirs, everywhere we have conventional production, there's a source rock associated with that and there's an unconventional reservoir, potential unconventional reservoir associated with that too. So really, all over the world, we have these unconventional reservoirs.
Mostly they've only been developed or exploited in North America, really in US and Canada. And we have a long history; 15, 20 years of development for these types of reservoirs here in the US and Canada. Other places are starting to see some development happening, particularly in Argentina, South America. And in China and in Russia, there's a lot of work going on today to figure out how to exploit their particular types of unconventional reservoirs. So again, most of it's happening here in North America, but really all over the world, people are doing work. In the Middle East, they're starting to do some early testing and that type of thing. So, maybe 5 to 10 years behind where the North America projects are.

05. Unconventional Oil Reservoirs - Origin Story - Elm Coulee Bakken (Montana)

I also just want to talk a little bit about how unconventional oil reservoirs started. And you may, oh yeah, I've heard about how unconventional got started and that's a guy named Mitchell in the Barnett. But for the oil part of the reservoir, it really started here in Montana in the Elm Coulee Field. So there was a geologist, Richard Findley, who kind of had been drilling wells in the Williston Basin for his entire career and always drilled through this Bakken formation. You'd get a little show of oil, but the permeability just wasn't there to complete it. But he had this idea of, man, if I could drill a horizontal well into that formation, maybe I could make a well out of it. And so, it took a lot of money, he convinced another company, he partnered with Lyco and they drilled a well in the 1999. It's a little short, 1,000 ft lateral, turn the well on and did really well. I mean it came on producing maybe one 100 bbl/d. And this is the time when good wells are producing 30 or 40 bbl/d, onshore. And so he was pretty happy with it, but it wasn't stellar. And then they said, well maybe we should frac this well? And not the multi-stage completions we're doing today, but really just a single hydraulic fracture, just a "pump and pray" or just a single stage completion. Just pump a bunch of sand and fluid down there and see what happens. And they did that in early 2000 and the well came back producing about 400 bbl/d and kind of the rush was on.
A couple of other companies, along with Lyco, bought a bunch of acreage here in eastern Montana and really started developing. And this is still early 2000s, kind of the same time things are happening in the Barnett with gas with Mitchell, this was happening with oil here in the Elm Coulee Field.
So this is 2005 that I'm showing here on the map. Notice there's very little activity happening in North Dakota at this point. So most of this is happening in Montana. And this is actually the same year that I came back to Montana to teach. And it was amazing that everybody was talking about it. It was kind of the big thing in Montana. The governor, we went from deficits to revenue in our government and it was a pretty big deal. And I kind of thought, oh yeah, that's happening everywhere. But really, it was just happening here in Montana for the oil.

06. Unconventional Oil Reservoirs - Origin Story - Bakken - Expanded Development

Now, if we just flash forward just five years into 2010, what we see is the Elm Coulee field is pretty much over. So each circle here represents a well, the size of the circle represents how much it's producing and then the colors represent how gassy it is. So yellow is more gas and red has the most. You can see in the Elm Coulee field, there's a few more wells now, but there are smaller circles and more gas in them. But over on the North Dakota side, man there's a lot more activity. And this is partly because there's a bigger area of potential production happening over there in North Dakota and the development started to pick up. And again, for me, like I grew up in this kind of small town, kind of middle of nowhere, didn't know much about the oil and gas industry. My friends from high school started getting jobs over here in North Dakota. I mean, it was a big deal, not just for North Dakota, but for the entire region. I mean, these friends with just a high school education, they'd come back, they'd have these big jacked up pickup trucks and made lots of money. And they knew kind of at that point what the oil industry was and how you can make some money in the area. So this is kind of the beginning of unconventional oil development.

07. Unconventional Oil Reservoirs - Origin Story - Continued Unconventional Oil Development

I'd say the next important place maybe is the Eagle Ford down in South Texas. So this is 2011, this is a year later than we showed before. And all the blue dots on here are permitted wells. So they haven't been drilled yet. Now you can see a few green wells, those are oil wells and a few red wells, those are the gas wells. But for the most, very little production happening in 2011.
But if we flash forward just four years later to 2015, boom, we see all this development, all these wells have been drilled. And, this is happening in the Eagle Ford. The Niobrara, probably similar things are happening in this time frame.

08. Unconventional Reservoirs - North America

If we look at other basins like the Permian, similar kind of stories happening between 2015 and 2020, as this explosion of development happened over a very short period of time and all these different basins. And we talk about Canada, the Montney and the Duvernay and the Utica in Ohio. In Oklahoma, the Stack/Scoop area. So really, this development has kind of been across all of North America.

09. Unconventional Oil Success - US

And it's been tremendous as far as the production that we have. So here I'm just showing US oil production from 1920 through today. I mean, you can see it peaked up in 1970 around 10 MM bbl/d, but it's pretty much been on a steady decline since then. This little blip right here in kind of the middle 80s is when Alaska came on. But really, we see kind of in 2005 or so this huge increase in production. And this is really the unconventional reservoirs coming online here in the US. And we far exceeded that 1970 peak of 10 MM bbl/d. It peaked at about 13 MMbbl/d. It's come back a little bit lately, but still over 10 MMbbl/d production. Again, the far majority of that probably 7 MMbbl/8 MMbbl, is actually coming from these unconventional plays. And it's made a huge difference in energy security. And again, these are all things you know, but just to be complete, there's a huge amount of oil in these reservoirs.

10. Unconventional Reservoirs - Need for EOR

So that's the good news, right? We have lots of oil in place in these reservoirs, hundreds of billions of barrels in each one of these basins. The wells come on at high rates, but they drop off quickly and we have really low recovery factors. So what does this tell us? Well, there's some need for some type of enhanced oil recovery. And that's really where this class comes in, right. We have lots of resource. We're getting a little bit out of it. Even in conventional reservoirs, we had the same problem in the 40s and we really developed some EOR techniques to accomplish that. So that's kind of where we're sitting today in unconventional reservoirs, ready to try to develop these unconventional reservoirs, some type of EOR with them.

11. Course Outline

So this last slide on this first lesson, just is kind of a course outline. It has lots more detail about the things we're going to talk about. Really get into some of the details on the Huff-n-Puff gas injection, how it works, different types of fluids we may be able to use. And then also a big chunk of the class is really on the operational aspects and implementing it. If you're an engineer looking to implement EOR in one of your fields, a big part of this class will talk about things to look for it and concerned you should have and things you should be thinking about and experiments you should be running and all those types of things.
So that's just the first lesson. The next lesson we'll start looking in a little bit more detail of what unconventionals, how they were formed and a little bit more background information. And then pretty soon we'll be off and running. So thanks a lot and we'll see you in a little bit.



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EOR for Unconventional Reservoirs Course
Chapter 1 - Introduction and Background (2:27:51)
Chapter 2 - Historical Development of EOR in Unconventionals (2:38:37)
Chapter 3 - Huff-n-Puff Gas Injection (2:52:00)
Chapter 4 - Other EOR Methods (1:14:58)
Chapter 5 - Operational Aspects (2:32:34)
Chapter 6 - Review & Summary (21:02)