Chapter 1 - Introduction

1.01 Course Introduction (9 min.) Sample Lesson
1.02 Acidizing Categories & Stimulation Options (8 min.)
1.03 History of Acidizing (14 min.)

Chapter 2 - Formation Damage Fundamentals

2.01 Formation Damage (17 min.)
2.02 Drilling & Completion Damage (16 min.)
2.03 Production Damage (26 min.)
2.04 Injection & Stimulation Damage (20 min.)

Chapter 3 - Acid Stimulation Chemistry and Physics

3.01 Acid Stimulation Chemistry and Physics (20 min.)

Chapter 4 - Sandstone Acidizing in Conventional Wells

4.01 Sandstone Acidizing in Conventional Wells (12 min.)

Chapter 5 - Sandstone Acidizing Design Process

5.01 Sandstone Acidizing Design Process (24 min.)
5.02 Sandstone Acidizing Design Process - Step 3 (17 min.)
5.03 Sandstone Acidizing Design Process - Step 4 (20 min.)
5.04 Sandstone Acidizing Design Process - Step 5 (17 min.)
5.05 Sandstone Acidizing Design Process - Step 6 (7 min.)

Chapter 6 - Carbonate Matrix Acidizing

6.01 Carbonate Matrix Acidizing (20 min.)

Chapter 7 - Carbonate Fracture Acidizing

7.01 Carbonate Fracture Acidizing (14 min.)

Chapter 8 - Production Well Acidizing Examples

8.01 Sandstone Acidizing Successful Case Examples (27 min.)
8.02 Carbonate Acidizing Successful Examples (12 min.)
8.03 Acid Tunneling - Open-hole Carbonate Stimulation (5 min.)

Chapter 9 - Injection Well Acidizing Examples

9.01 Injection Well Acidizing Examples (10 min.)

Chapter 10 - Unconventional Well Acid and Matrix Stimulation Applications

10.01 Unconventional Well Acid Stimulation Applications (14 min.)
10.02 Final Comments (13 min.) Quiz: 10.02 Final Comments

Acid and Matrix Stimulation in Conventional and Unconventional Wells / Chapter 1 - Introduction

Lesson 1.01 Course Introduction

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Transcript

01. Lesson 1.01: Course Introduction 02. Course chapters 03. Key References 04. Chapter 1 - Introduction 05. We pumped acid. it didn't work 06. Acid is acid 07. We don't have a fines migration problem 08. We'll just stimulate water production 09. There are too many reasons why an acid job can fail 10. Sandstones 11. Carbonates 12. Acidizing results can be spectacular

01. Lesson 1.01: Course Introduction

Hello, I'm Leonard Kalfayan. Welcome to this course on Production Enhancement, specifically Acid and Matrix Stimulation in Conventional and Unconventional Wells. My background is, I have over 43 years in the oil and gas and geothermal industries, primarily production enhancement applications, technology development and business development. I've worked for 2 different operators, Unical Corporation and the Hess Corporation, as well as a pumping service company, the former BJ Services prior to being acquired by Baker Hughes.

02. Course chapters

These are the course chapters, 10 chapters. We start with an introduction which includes a history of acidizing, because I think it's for your appreciation of acidizing, and there are some important points and learnings from that history. Then formation damage fundamentals, which is a lengthy section, but it's important to precede the acid stimulation design process. Then Chapter 3 is on acid stimulation chemistry and physics. And just an overview of that and really focusing on as the rest of the course is on just what I think is important to note to gain facility in these different topics. And then Chapter 4 is sandstone acidizing in conventional wells. Chapter 5 is the sandstone acidizing design process, a step-by-step process from identifying formation damage all the way through treatment evaluation. And that process also applies to carbonate acidizing, but it's much more involved with sandstone. So that's where we will take that up. And Chapter 6 is carbonate matrix acidizing followed by carbonate fracture acidizing in Chapter 7. In Chapter 8 and 9, we get into case examples. Chapter 8 being production well examples in both sandstones and carbonates. Chapter 9, injection well examples. And then Chapter 10 unconventional well acid and matrix stimulation applications. And then end with some final comments and summary comments and some little words of advice.

03. Key References

And these are the list of key references that really support the development of this course. And with some of these, you can really go into much greater detail in certain aspects of what's covered. For example, with acid stimulation, chemistry and physics, the 3rd bullet there, the book "Reservoir Stimulation" that goes into considerable detail on that, as well as treatment economics, treatment evaluation. So it is the first book listed there the SPE monograph on acid stimulation. And for those 2 references, each chapter is written by 1 or 2 experts in those topics. So those are valuable resources. And the others are as well.

04. Chapter 1 - Introduction

All right, Chapter 1 is introductory material.

05. We pumped acid. it didn't work

Now, I'm going to start with a list of statements that have been said to me. I've had answers to those over the years. Maybe you said some of these yourselves. It's ok if you have. It's understandable. Such as "We pumped acid. It didn't work". A well must have acid-removable wellbore formation damage or if not, its producing formation must be highly reactive to acid, such as a carbonate for there to be a positive response. If there is formation damage, then proper stimulation fluids must be used.

06. Acid is acid

"Acid is acid". In the industry, acid is often thought of generically as just hydrochloric acid. That's certainly the most common acid, most commonly used acid. But other acids may be needed depending on well conditions and treatment objectives. In sandstones, hydrofluoric acid (HF acid) is very often necessary, specifically to remove plugging from fines migration, which is the most common damage mechanism in sandstones.

07. We don't have a fines migration problem

But "We don't have a fines migration problem". Well, if the well is producing from a sandstone and the production decline is greater than the natural decline or there is an evidence of increasing skin, fines migration should be assumed unless it could be definitively ruled out.

08. We'll just stimulate water production

"We'll just stimulate water production". Well, that's always a risk with acidizing. So of course, it's important to know where water is coming from if that's possible. But selective stimulation of hydrocarbon zones is possible with acid placement diversion techniques that we'll discuss later in the course that enable avoiding or at least reducing injection of stimulation fluids into water-producing zones.

09. There are too many reasons why an acid job can fail

Well "There are too many reasons why an acid job can fail". Well in fact, there is a limited number of reasons why a sandstone acid job can fail and even less with carbonate acidizing, carbonates are more forgiving with respect to acid stimulation. And besides unforeseen equipment failures during a treatment, all of these reasons can be addressed.

10. Sandstones

Now, this is a list of reasons or why sandstone acidizing treatment could fail. And it looks like a lot there but really some of these are related. So if you address one, you're really addressing multiple reasons. Failure to clean acid or water tanks, of course, that's given. The formation is not damaged or does not have acid-removable damage, that's really a requirement with sandstone acidizing. Removable damage is present, but the wrong type of acid is used. And, for example, if it's fines migration and you have fines plugging that treat with only hydrochloric acid, you're not likely to have much of a response. Using improper acid volumes through the formation too much or too little. Using acid mixtures that are incompatible with formation fluids. That is acid and heavy oil can be challenging without certain additives. Additive overuse or misuse. Pumping the acid job above fracturing pressure. Preferentially stimulating water production due to inadequate placement or diversion. Or shutting in an HF acid in the formation for too long, and then re-precipitation of products occurs and that can cause a reduction in permeability. But again, all can be addressed and with proper well evaluation, treatment planning, design and execution.

11. Carbonates

Now, with carbonates, there are less reasons why an acid job can fail. Some of them, of course, the same failure to clean acid or water tanks. Using a weak acid in a low temperature dolomite. Dolomite does not react as fast as a limestone, for example, with hydrochloric acid or with organic acids. Fracture acidizing a carbonate with high sandstone mineral content using insufficient acid volume, really that means too little acid. Again, additive overuse or misuse. And then preferentially stimulating water production due to inadequate placement or diversion. Again, all can be addressed with proper well evaluation, treatment, planning, design and execution.

12. Acidizing results can be spectacular

And the fact is that acidizing results can be spectacular. I want you to have that in mind. But acidizing, especially with HF acid in sandstones, is historically underappreciated and still underutilized. With carbonates, not so much because that's a simpler process. But with sandstones, there's that fear especially with hydrofluoric acid and that does hold it back to some extent. All right, that's it for this lesson within this introduction chapter.
And the next section of this chapter is Acidizing Categories and Stimulation Options.
Syed A. Ali, Carl Montgomery, and Leonard Kalfayan, L. (editors). 2016. Acid Stimulation. SPE Monograph Series, Vol. 26 Leonard Kalfayan. 2008. Production Enhancement with Acid Stimulation, 2nd edition. Tulsa: PennWell Corporation.Kenneth G. Nolte and Michael J. Economides (editors). 2000. Reservoir Stimulation, 3rd edition. Schlumberger Kalfayan, L.J. and A.N. Martin. 2009. The Art and Practice of Acid Placement and Diversion: History, Present State and Future. Paper SPE 124141 Kalfayan, L.J. 2007. Fracture Acidizing: History, Present State, and Future. Paper SPE 106371 P. Rae and G. di Lullo. 2003. Matrix Acid Stimulation – a Review of the State-of-the-Art. Paper SPE 82260 McLeod, H.O. Dec. 1, 1984. Matrix Acidizing. J. Petroleum Technology 36 (12); p. 2055-2069