NEW DEGRADABLE POLYMERS for 2015

Presented by C. Andrew Rosenholm

President, Rockwell Oil & Gas Sales, LLC

2015 Winter Technical Meeting

TABLE OF CONTENTSSlide #2: Table of contentsSlide #3: IntroductionSlide #4: Why degradable polymers are used downholeSlide #5: Why degradable polymers are used downhole (continued)Slide #6: History (brief) of degradable polymersSlide #7: 2013 PGA becomes popularSlide #8: 2014 Degradable updateSlide #9: Types of polymer degradationSlide #10: Methods for forming polymers and thermosetsSlide #11: New degradables for 2015Slide #12: New degradables for 2015 (continued)Slide #13: New degradables for 2015 (continued)Slide #14: Degradable ball usesSlide #15: Degradable ball uses (continued)Slide #16: Biodegradation of polymer is a function of:Slide #17: Degradable polymer & metal brand namesSlide #18: Tensile strength of degradable polymersSlide #19: Degradation rates of polymersSlide #20: Specific gravity of degradable resinsSlide #21: ConclusionsSlide #22: Appendix

This presentation is focused upon the use of degradable polymers in downhole oil & gas applications. I’ve spent four years refining the manufacturing process for making balls used in hydraulic fracturing procedures (frac balls), and I have been working with degradable polymers and metals for the last two years. I have 20 years experience in tool making, precision machining and injection molding.

In this presentation I will review degradable polymers with respect to their usefulness in making frac balls and by extension, other products used downhole such as frac plugs, etc.

All brand names mentioned here are the property of their respective owners and are mentioned solely to provide a functional context for the polymers referenced in this presentation.

INTRODUCTION

C. Andrew RosenholmJanuary 2015

Degradable polymers are used in applications where downhole tool retrieval may not be possible or cost-practical.

Removing a stuck Ø 1 ½” ball from one mile underground may necessitate the use of extreme measures:

WHY ARE DEGRADABLES USED DOWNHOLE?

COILED TUBING INTERVENTION $30k-$100k

What if the tools you used downhole simply disappeared after use? The concept of the disappearing tool has been successfully employed in ligament reattachment, sutures, food service and golf tees. The first attempts at using degradables downhole relied on bio-based compounds such as animal fats and plant starches. The first commercially successful application of degradable polymers downhole was the application of polyglycolic acid (PGA) – a resin originally developed for packaging applications – for making frac balls.

VERY BRIEF HISTORY OF DEGRADABLE POLYMERS

PGA FRAC BALLS BECAME POPULAR IN 2013

PGA features a high degree of crystallinity = high strength. The high degree of crystallinity in PGA necessitatessustained temperatures of > 200° F to degrade.

© Kureha

In 2014 interest became strong in new polymers that will• Degrade in temperatures < 200° F. • Cost less than PGA or MgAl composites

2014 DEGRADABLE UPDATE

Degradable metal balls become popular: MgAl composites or alloys• Baker-Hughes IN-Tallic™• exSolv Metall ™• Schlumberger ELEMENTAL™• Terves TervAlloy™

One new non-metal degradable was introduced: Parker Phantom™ - thermoset/phenolic composite ball

Bulk degradation (PLA,PGA,PLGA, PCL) Degradation takes place throughout the whole of the sample Ingress of water is faster than the rate of degradation

Surface erosion (poly(ortho)esters, polyanhydrides, polyvinyl alcohol) Sample is eroded from the surface Mass loss is faster than the ingress of water into the bulk

TYPES OF POLYMER DEGRADATION

© Rockwell Oil & Gas Tool Sales, LLC 2014

© Rockwell Oil & Gas Tool Sales, LLC 2014

METHODS OF FORMING PLASTICS AND THERMOSETS:

Extrusion: Must be machined into the final shape

Injection: Near-net shape forming Compression: Net-shape forming

AnisotropicMechanicalCharacteristics

IsotropicMechanicalCharacteristics

NEW DEGRADABLES FOR 2015:

Polyvinyl Alcohol (PVOH, PVA, or PVAl) in neat and reinforced blends

Polylactic Acid (PLA):Reinforced and modified with enhanced degradationproperties

© Rockwell Oil & Gas Tool Sales, LLC 2014

• PGA/PLA Blends• USA-Made PGA

Glycolic Acid Telomer (GAT): Properties similar to PGA, utilizes a different synthesization process

Degradable Amorphous Polymer

Polyvinyl Alcohol (PVOH)

All carbon backbone polymer

Degradable Semi-Crystalline Polymers: Aliphatic polyesters

Polyglycolic Acid (PGA)

Polylactic Acid (PLA)

Degradable Thermoset/Phenolic

Composites

Contain reactive metals (Mg, Al,

Zn, Na, Ca)

BIODEGRADATION OF POLYMER IS A FUNCTION OF:• Molecular weight• Morphology (crystallinity)• Polymer structure (e.g. hydrolysable backbone)• Mechanical breakdown due to degradation of composite additives

© Rockwell Oil & Gas Tool Sales, LLC 2014

Ball applications for degradable polymers:• Stage balls – sliding-sleeve• Plug-and-perf frac plug balls• Ball diverters for bullet perforations, etc.

Non-ball applications for degradable polymers:• Frac plugs – Magnum Oil Tools• Diverter agent – Halliburton AccessFrac ™ Biovert ™

© Halliburton

DEGRADABLE POLYMER TYPES USED IN DOWNHOLE APPLICATIONS:• PGA – Polyglycolic Acid (Magnum Fastball™)• PLA – Polylactic Acid (Santrol Bioball™)• PVOH – Polyvinyl Alcohol (Santrol Bioball™)• Phenolic – Thermoset composite (Parker Phantom ™)

GF-PLA PVOH PGA Mg MgAl0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

TENSILE STRENGTH (psi)

Phenolic PGA PLA-Mod PVOH0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

DEGRADATION RATES (APPROXIMATE)

Degradation Rate 70° F/10 hrs. Degradation Rate 200° F/10 hrs.

Phenolic PGA PLA-Mod PVOH0

0.5

1

1.5

2

2.5

Specific Gravity (g/cm^3)

SPECIFIC GRAVITY (SG) OF NEAT RESINS, SG can be increased or decreased by compounding with fillers

2013

• Degradables become popular for downhole use with widespread acceptance of PGA taking place

2014

• Competitors to PGA begin to emerge – predominantly in the form of degradable metals, but also in thermoset/phenolic form

2015

• As oil prices continue to drop, price will become more important to completions providers

• More options sought for degradation rates

• New degradable polymers are introduced that offer options for degradability rates and price:

• PVOH alloys and composites• PLA alloyed to degrade more rapidly• New PGA composites and alloys

CONCLUSION:

Ball sealers/ball diverters:

Ball Sealers Brand names: Soluball ™; Bioball ™

Ball sealers can be divided into two categories: those heavier (sinkers) and those lighter (floaters) than the fluid.Successful use requires a good cement job on the installed casing and round good quality perforation holes. Sinkers have been used the longest and usually require 200% excess ball sealers and a high pump rate (greater than 5 bbl/min). The high pump rate usually prohibits their use in sandstone matrix acidizing,but they may be used in fracture acidizing or perforation breakdown. Floaters, or neutral-density ball sealers, provide excellent mechanical isolation for matrix acidizing at injection rates of 1 bbl/min or higher. The density or specific gravity of these ball sealers is matched to the fluid being pumped so better ball action will take place. Surface flowback equipment must be modified to catch the floating ball sealers during flowback.

Ball sealers are limited in their use. They are not used in long intervals with high-perforation density, wells perforated with more than 4 shots/ft, low-rate treatments (¼ to ½ bbl/min), and gravel-packed wells. Regardless of the type of treatment or ball used, treatment will be more effective when density of the ball is very close to the density of the fluid used in the treatment.

Credit:Petroleum Engineering HandbookLarry W. Lake, Editor-in-ChiefVolume IV - Production Operations EngineeringJoe Dunn Clegg, EditorCopyright 2006, Society of Petroleum EngineersChapter 7 – Matrix AcidizingHarry O. McLeod, SPEPgs. 275-321ISBN 978-1-55563-118-5

Schlumberger Oilfield Glossary:ball diverter

1. n. [Well Workover and Intervention]Small spheres designed to seal perforations that are accepting the most fluid, thereby diverting reservoirtreatments to other portions of the target zone. Ball sealers are incorporated into the treatment fluid and pumped with it. The effectiveness of this type of mechanical diversion to keep the balls in place is strongly dependent on the differential pressure across the perforation and the geometry of the perforation itself

Credit:Publication number US7647964 B2Publication type GrantApplication number US 11/640,813Publication date Jan 19, 2010Filing date Dec 18, 2006Priority date Dec 19, 2005Fee status PaidAlso published as US20070169935Inventors Syed Akbar, Patrick R. Okell, A. Richard SinclairOriginal Assignee Fairmount Minerals, Ltd.

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