hydraulic fracturing basics

8/12/2019 Hydraulic Fracturing Basics

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Hydraulic Fracturing Basics

Jennifer L. Miskimins, Ph.D., P.E.

Associate Professor

Colorado School of Mines

December 3, 2009


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Outline

General hydraulic fracturing

Why we do it Evolution of fracturing techniques

How it works

Conventional vs. unconventional reservoirs Resources


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General Hydraulic Fracture Process

Inject a pad (fluid, no solids) at a sufficient pressure

and injection rate to breakdown (crack) the formation; Inject a slurry (fluid w/ proppant) to propagate and

develop the fracture;

Shut down the injection at the surface and allow thefracture to close around the injected proppant;

Flow back the well to clean up the fluids; and,

Start producing the well.


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Producing Zone


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Oilfield Stimulation History

Acidizing and nitroglycerin were the mainstimulation services provided until the late1940s.

In 1947, the first intentional fracturetreatment took place in the Hugoton gas fieldof western Kansas. It was pumped in theKlepper Gas Unit No. 1 well and was called ita hydrofrac.


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Hydraulic Fracturing

Critical completion technique in low

permeability sands In 1989, it was estimated that 35-40% of all

wells completed worldwide were fractured

and in the United States and that 25-30% of

reserves would not be economicallyproducible without hydraulic fracturing

In certain areas, +95% of wells are fractured


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Why we do it?

Bypass near-wellbore damage

Extend a conductive channel into reservoir(increases/stimulates natural productivity of

well)

Alter flow in formation

Reservoir management


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Fracturing Fluids

Ideal properties1. Adequate viscosity

2. Good fluid loss control

3. Low residue

4. Low friction pressure

5. Temperature and shear stable throughout the

treatment6. Non-damaging to formation

7. Easy to prepare

8. Easy to recover

9. Cost effective


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Fracturing Fluids

Main types of fluids

Water-based (slickwater) Oil-based

Acid-based

Multiphase (foams)


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Dimensionless Fracture Conductivity

kf= fracture permeability, mD

w = width of fracture, ft

k = permeability of formation,

mD

Xf= fracture half-length, ft

f

f

CDkX

wkF =


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Generic Proppant Types

Sand

Artificial or ceramics


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Proppant Comparisons - Shape

White Sand Artificially

Manufactured


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Proppant Comparisons - Shape

API RP60, From Stratigraphy and Sedimentaion, Krumbein and Sloss

Qualityceramics

Premium

sands

Many

sands

Roundness

Sphericity

0.1 0.3 0.5 0.7 0.9

0.3

0.5

0.7

0.9


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Conventional vs. Unconventional

From Holditch 2001


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From Green 2006

Multiple Vertical Completions


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Drainage Areas

Horizontal well system Vertical well system

Vertical vs. Horizontal Completions

From Miskimins 2008


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References

www.energyindepth.com/PDF/At-A-

Glance.PDF www.all-llc.com

www.garfield-county.com
http://www.energyindepth.com/PDF/At-A-Glance.PDFhttp://www.energyindepth.com/PDF/At-A-Glance.PDFhttp://www.all-llc.com/http://www.garfield-county.com/http://www.garfield-county.com/http://www.all-llc.com/http://www.energyindepth.com/PDF/At-A-Glance.PDFhttp://www.energyindepth.com/PDF/At-A-Glance.PDF


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QUESTIONS?

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