Li Jiang Tendeka

1. 1
ScaleFizz Self-agitating Mineral Scale Remover
Li Jiang, Suzanne Stewart and Jonathan Abbott

2. 2
Scale Formation Problems
▪ Solid deposits that accumulate
over time, hindering and blocking
fluid flow through tubing, casing,
valves and pumps resulting in
significant reduction in production
rates and equipment damages.
▪ Organic deposit occurs due to
changes in T, P and flow rate
▪ Mineral scale happens when
incompatible waters encounter
Solid Deposit
Organic
Deposit
Mineral
Scale
Wax/Paraffin
Asphaltene
Carbonate
Sulfide
Sulfate

3. 3
Scale Management Strategies
▪ Scale Inhibition scale inhibitor
formulations are
1. Squeezed into formation
2. Batch injected into wellbore
3. Continuously injected in
wellbore
▪ Scale remediation
1. Mechanical:
a. abrasive jetting
b. milling
2. Chemical:
a. acid wash
b. scale dissolution
Scale
Management
Inhibition Remediation
Squeeze
into
Formation
Continuous
injection
in
wellbore
Acid
spearhead:
Carbonate
and
sulfide
Scale
dissolver:
Sulfate
Batch
injection
in
wellbore

4. 4
Chelating Ligands for Scale Prone Cations
Chelating Agents originated from a variety linear and
cyclic ligands offering oxygen and/or nitrogen binding sites
4
EDTA DTPA NTA TETA EDDHA
TETRAAZA CROWN
ETHER
CRYPTAND BEAUVERICIN VALINO-
MYCIN

5. 5
Sulfate Scale Dissolution
Chelating agent
provides higher binding energy to divalent metal cations than the salt anion can offer, therefore
capable of driving the equilibrium forward to thermodynamically more stable 3D complex cage
5
MSO4 (M=Ca, Ba, Sr)
CaSO4 SrSO4 BaSO4
Ksp 7.1 x 10-5 3.5 x 10-7 1.1 x 10-10

6. 6
Chelating Ligand Based Scale Dissolver
▪ Chelating Ligand based scale dissolvers afford considerable
dissolution capacity in thermodynamic sense, but
▪ Suffer from extremely sluggish dissolution rate
▪ In addition, spatial restriction in downhole environment limiting
access of sufficient scale dissolver fluid to the scale
▪ Furthermore, the dissolution process can only tackles the scale
matrix one layer at a time
▪ Finally, the static fluid-scale interface prevents effective replenish of
fresh dissolver, retarding the mass transfer mechanism
▪ Overall, the depressed dissolution kinetics is the primary bottle-neck
of chelating ligand-based scale removal treatment job

7. 7
Engineering strategies to enhance scale dissolution rate
▪ In the absence of any viable option to significantly changing the chemical kinetics, or
having to resort to mechanical means, we developed two synergistic, chemistry-based
approaches aimed at generating localized fluid momentum which, in turn, serves to
enhance mass transfer rate at the scale-fluid interface:
▪ Foaming agent: is able to capture entrained gases into micro and/or nano foams and
migrate along the pressure differential through the wellbore, hence generating fluid
motion to facilitate fluid replenish at the scale-fluid interface
▪ Gas generation reaction: decomposition of precursor molecules under thermal driving
force, and/or in the presence of catalyst, resulting in localized gas generation at the
scale-fluid interface, therefore enhancing mass transfer rate at the scale-fluid interface

8. 8
Foaming agent enhances scale dissolution rate
8
Test
ID
Foaming agent type Mass
(%)
+Mass
(folds)
0 None 2.55 0
1 Propoxylated-N-tallow alkyltrimethylene
diamines
5.77 2.26
2 Ethoxylated & propoxylated castor oil 5.41 2.12
3 Polypropylene stearyl ether 5.19 2.04
4 Oligomeric alkylethylene oxide I 5.05 1.98
5 Oligomeric alkylethylene oxide II 5.33 2.09
6 Poly(alkyleneoxide) block copolymer 5.45 2.14
7 Poly(oxybutylene)-poly(oxyethylene)-
poly(oxybutylene) triblock copolymer
5.94 2.33
8 Polyethylene sorbitan ester 4.35 1.71
9 Polyoxyethylenesorbitan monooleate 4.14 1.62
Qualification Test Specs
1. Scale dissolver: commercial
product based on chelating
ligand
2. Scale sample: SrSO4 obtained
from W. Texas oil well
3. Dissolver/scale mass ratio: 20/1
4. Foaming agent concentration
200ppm
5. Gas generation precursor 1%
6. Reaction vessel: measuring
cylinder
7. T: 74F
8. t: 3.5 hrs

9. 9
in-situ Gas generation enhances scale dissolution rate
Test ID Gas generation reaction type Mass (%) +Mass (fold)
0 None 1.82 0
1 Na2CO3 + H2O CO2 + NaOH 5.27 3.47
2 NH4Cl + NaO NH3 + NaCl + H2O 4.54 2.49
3 (NH4)2CO3 2NH3 + CO2 12.56 6.90
4 H2N-CO-NH2 + H2O 2NH3 + CO2 12.35 6.79
5 2H2O2 O2 + 2H2O 13.52 7.43
Qualification Test Specs
As per previous test

10. 10
Case Study—Candidate Spec
▪ Eastern Texas, sandstone formation, injection
well
▪ Root cause of scale: repeated waterflooding
since 2013 led to incompatibility with formation
water in perforation (118 ft) and near wellbore
regions
▪ Scale identity verified by XRD as BaSO4
8353ft
8417ft

11. 11
Case Study—Treatment Outcome
▪ Treatment job details
▪ Volume of ScaleFizz fluid pumped 6 M3
▪ Soak time: 18 hours
▪ Average Tubing Pressure
57 psi lower Average Tubing Pressure vs Average Formation Pressure
▪ Shut In Tubing pressure
300 psi increase during soak indicating clean out of perforation and near wellbore regions
▪ Average Injection Rate
Increased from 7 MMCFD to 12 MMCFD, peaked at15 MMCFD, an improvement up to 214%
• Cost Savings
Time, Money & Materials
▪ Shortened soak time, allowing Injector to come back online with minimized shut in time
▪ Extend the service life of the tubing and packer
▪ Forgo disposal of NORM contaminated equipment

12. 12
Conclusions
▪ Downhole scale formation is a serious hazard to the production or
injection rate and asset integrity
▪ Scale removal treatment associated with static local environment is
hindered by several intrinsic and practical factors
▪ Technical strategy leading to scale dissolution rate enhancement is
highly desirable
▪ Micro/nano gas encapsulation in conjunction with localized gas
generation approaches can result in significant increment of scale
dissolution rate
▪ This approach should also be applicable for organic deposit treatment
▪ Expansion of field trial campaign underway

13. 13
Acknowledgements
▪ Co-authors for their input to the work
▪ Tendeka management for allowing this presentation
▪ HFPC organizers, in particular program manager and
session chairs, for their assistance and support through a
process leading to this presentation.
Thank You
▪ For your attention
Questions ?
• ScaleFizz • Li Jiang

14. 14
Thank You
14