The document discusses a presentation on controlling scale deposition in oil fields. Primary funding for the Society of Petroleum Engineers Distinguished Lecturer Program comes from member donations and contributions from industry partners. The presentation covers topics like scale types, prediction, inhibition strategies, case studies, and chemical quality control. Preventing scale before it starts to form is emphasized as the most cost-effective approach to dealing with scale formation in oil and gas production.

1. Primary funding is provided by
The SPE Foundation through member donations
and a contribution from Offshore Europe
The Society is grateful to those companies that allow their
professionals to serve as lecturers
Additional support provided by AIME
Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl
1

2. Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl
2
Controlling Scale Deposition:
Advances in Using Technology to
Preserve Production in the Oil Field
Charles Hinrichsen
Chevron Energy Technology Company
(Retired)
Houston, Texas USA

3. Outline:
• Scale: Description and Causes
• Scale Inhibition Strategy
• Scale Prediction: Scale Tendency and Inhibitor Dosage
• Scale Inhibitors: Evaluation and Application
• Case Histories
• Other Scale Mitigation Methods
• Chemical Quality Control
• Summary
“Imagine an oilfield menace that can smother a productive well within 24 hours. The
buildup of scale inside wellbores does exactly that, causing millions of dollars in
damage every year!" Crabtree, et. al., “Fighting Scale - Removal and Prevention”,
Oilfield Review (Schlumberger), 1999, pp 30 – 45.
3

4. What is “Scale”?
FexSy
CaSO4 CaCO3
BaSO4 CaSO4 / CaCO3 CaSO4
4

5. Main Scale Types
Inorganic OrganicGas
Naphthenates
Hydrates Asphaltenes
Waxes
Halides
Carbonates
Sulfates (NORM)
Sulfides
Oxides /
Hydroxides
Main Scale Types
Scale Types
CaCO3
BaSO4
CaSO4
NaCl

6. 6
3
+2
4
-2

7. 7
The Most Cost-Effective
Method for Dealing with
Scale Formation….
PREVENT scale
before
it starts to form!!

8. 8
The Problem With Predicting Scale:
• Thermodynamics: Controls solubility
Over- or under-saturated?
Scale or no scale?
• Kinetics: The rate at which scale forms
Even though scale may be
thermodynamically favored, it may
take a long time to form!

9. 9
Scale Formation:
Laminar flow Turbulent flow
SPE-179863-MS, May 2016. Photos and chart courtesy of BCC Rice University
Nucleation
Induction time

10. 10
Relating Scale Risk to Inhibitor Dosage (ppm)
SPE-184518-MS, April 2017; Chart courtesy of BCC Rice University.
Production
profile

11. 11
Abbreviation Chemical Name
Hexa-P Hexa-phosphonate
DETPMP Diethylene-triamine-pentamethylene phosphonate
PPCA Polyphospheno-carboxylic acid
PVS Polyvinyl sulfonate
Vs-Co Vinyl sulfonate co-polymer

12. 12
Evaluating Scale Inhibitor Performance
Dynamic Flow Loop Testing
0
0.5
1
1.5
0 10 20 30 40 50 60
FlowLoop
Pressure(psi)
Time (min)
5 mg/L 3 mg/L 1 mg/L

13. 13
Scale Inhibition Strategy:
• Evaluate Scaling Condition (location and
type of scale)
• Perform Laboratory Testing
• Select Inhibitor Based on Effectiveness,
Brine Chemistry, and Temperature
• Design a Treatment Plan
• Implement in Field

14. 14
Application of Scale Inhibitors
• Continuous
• Squeeze Treatment
► The inhibitor must be present at all times
in the water being treated.
► Need to inhibit the growth of SCALE at the
source – that is, at the LOCATION where the
scale crystals begin to grow and ADHERE to
surfaces.
► The inhibitor should be added UPSTREAM of
the point where scale deposition starts to
occur.

15. 15

16. 16
Scale Inhibitor Return
Volume of Brine (bbl)
BHTMP(mg/l)
BHTMP = Bis(HexaMethylene Triamine Penta (Methylene Phosphonic Acid))

17. 17
HOWEVER, the actual treatment may result in an uneven distribution of scale inhibitor
because of permeability variations in different zones.

18. 18
Squeeze Design: Recommendations
Modelling tools may assist with understanding what is
best scale management option…
calculate chemical requirements for squeeze
provide input for an economic model
Particularly important in deepwater environments, where
intervention may be difficult and expensive
But – must be aware of reservoir uncertainties…
changes to production schedule, etc.
Monitoring is essential.

19. 19
Case History:
NORM: A Unique Form of Scale
It’s radioactive!
•First widely acknowledged in 1980s
•Radionuclides (natural origin) become
concentrated during scale formation
•Usually associated with BaSO4 (not CaCO3)
•Sulfate scales may contain substituted Ra+2,
giving the scale its radioactive character.

20. 20
NORM Scale:
Safety Concerns: Handling and disposal of
radioactive waste require proper training.
•Hazards arise primarily from exposure to NORM
material in decommissioned equipment: well
tubulars, surface piping, vessels, pumps,
processing equipment
•Inhalation, ingestion, dermal (skin) adsorption
•Litigation more expensive than prevention
“The trend in upstream environmental litigation is simply
that more litigation is on the horizon.”1
SPE 125661, 2010

21. 21
Other Scale Mitigation
Methods:
• Sequestrant Addition (EDTA?)
• Dilution (may not be practical)
• Temperature and Pressure Control
• Control Water Handling Strategy
• Acid Addition (used for calcite only)
• Ion Exchange Softeners / RO Membranes
Scale Removal (if necessary):
HCl, Chelants (EDTA), etc.

22. 22
Chemical Quality Control
• How do I know if the chemical I ordered is
the same as what is delivered to the field?
• Will the chemical quality / composition remain
the same from one shipment to the next?

23. 23
Chemical Quality Control
Is the chemical in the
field the same as
what was purchased?
Spectroscopic
Fingerprinting:
• FT-IR
• NMR

24. 24
Summary
 Scale formation can be a show stopper if not
properly managed!
 Prevent scale BEFORE it starts to form!
 There are many scale prevention strategies and
scale inhibitor chemistries and application
techniques that, if properly implemented, can offer a
way to economically prevent the loss of production
caused by scale formation.

25. 25
Thank You!
corrosionchemist@gmail.com

26. Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl 26
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