A break-through corrosion inhibitor technology for heavily fouled systems
Submitting InstitutionUniversity of Hull
Unit of AssessmentChemistry
Summary Impact TypeTechnological
Research Subject Area(s)
Chemical Sciences: Physical Chemistry (incl. Structural), Other Chemical Sciences
Engineering: Materials Engineering
Summary of the impact
In partnership with the US company Nalco, the University's Surfactant
& Colloid Group developed
a new multifunctional technology (Clean n Cor) for the oil industry that
both removes accumulated
deposits at a metal surface (enabling "break-through" of corrosion
inhibitor to the metal surface)
and inhibits corrosion. Clean n Cor technology not only protects assets
such as oil pipelines
against corrosion but also maximises oil production through enhancing
water injectivity (water flow
per unit pressure drop). Since its launch in 2007, it is currently one of
Nalco's fastest growing new
technologies and is used at over 100 production locations worldwide.
Organic corrosion inhibitors with surfactant properties are widely used
to inhibit the corrosion of
oilfield equipment. Injected into piped liquids, they work by adsorbing at
the aqueous solution-
corroding metal surface where they commonly reduce the corrosion rate by
>95%, thereby saving
cost/environmental impact. However, their performance over time
deteriorates due to the
accumulation of oily deposits mixed with clays, corrosion products and
"schmoo") at the metal surface. The accumulation of schmoo on internal
pipe surfaces not only
prevents the corrosion inhibitor reaching the metal surface but also
adversely affects water
injectivity (e.g. by reducing the effective internal diameter of a pipe)
and thereby causes problems
with many oilfield operations.
The key research from Hull underpinning Clean n Cor development was in
several stages. The first
stage was to realise that the behaviour of surfactant-like corrosion
follows the patterns of microemulsion phase behaviour of conventional
systems enabled the exploitation of Hull's leading work in this area.
Early work (published pre-1993
and so not included here) at Hull had significantly advanced the
understanding of how oil
solubilisation can be maximised and how the oil-water tension can be made
ultra-low by "tuning"
the tendency of the adsorbed surfactant monolayer to curve — both factors
are of critical
importance in maximising schmoo removal from corroding metal surfaces.
Secondly, the post-1993 research that underpinned the development of
Clean n Cor1-4 investigated
the inter-relationships between the solid-oil, solid-water and oil-water
interfacial tensions to
understand the surface chemistry relating to the removal of oil from
capillaries and the adhesion of
different materials to solid surfaces. It identified the key factors
responsible for the adhesion of the
schmoo to the metal surface and how they could be manipulated, using the
microemulsion behaviour, to ensure good removal. The research described in
Ref. 5 then
developed a laboratory-based schmoo removal test cell which (i) enabled
validation of the
fundamental concepts described above and (ii) showed excellent correlation
performance of the multifunctional inhibitor systems. It was used to
provide a rapid screening of
different complex formulations and thereby enable the product launch of
the optimised Clean n Cor
Thirdly, although very successful in most oilfield application sites, it
emerged that Clean n Cor was
not sufficiently effective against the schmoos formed in some particular
oilfields and Nalco
commissioned further research at Hull in 2012-13 to investigate. The Hull
showed that schmoo from the problem sites contained additional solid
components which caused
the main removal mechanism to switch from "roll-up" and emulsification (as
seen in 5) to one of
solubilisation. Additional principles governing the design of Clean n Cor
formulations for such
problem sites were established and experiments demonstrated the enhanced
performance of new
formulation. This recent work is fully described in a commercially
sensitive and confidential report.
The underpinning research was undertaken at the University of Hull from
1993 to 2013 by Paul
Fletcher (Professor, since 1984), Robert Aveyard (Professor, 1965 to
2001), Bernard Binks
(Reader 1988 to 2002, Professor 2002 to present) and John Clint (Reader
1993 to 2006).
References to the research
(1) Displacement of oil by aqueous surfactant solutions from capillaries
sealed at one end.
R. Aveyard, B.P. Binks, S. Clark and P.D.I. Fletcher, Colloids &
Surfaces A, 1996, 113, 295.
(2) Adhesion under water: surface energy considerations. J.H. Clint and
A.C. Wicks, Int. J.
Adhesion & Adhesives, 2001, 21, 267.
(3) Adhesion and components of solid surface energies. J.H. Clint, Curr.
Opinion Colloid &
Interface Sci., J.H. Clint, 2001, 6, 28. (Although a review
article, this reference is included
here as it contains original analyses by Clint of data published by other
(4) "I put it in, but where does it go?" - The fate of corrosion
inhibitors in multiphase systems.
D.I. Horsup, J.C. Clark, B.P. Binks, P.D.I. Fletcher and J.T. Hicks, NACE
Conference 2007, paper 06717, 1-32.
(5) A break-through corrosion inhibitor technology for heavily fouled
systems. D.I. Horsup, T.S.
Dunstan and J.H. Clint, Corrosion, 2009, 65, 527.
Details of the impact
The non-academic beneficiaries in terms of positive economic impacts from
research are Nalco — which has a successful and effective commercial
product line specifically
developed with the problem in mind, and its customers who use this product
(Clean n Cor). Clean
n Cor helps to decrease integrity risks by mitigating the potential for
under deposit corrosion in
production pipelines which has added benefits for the environment in
reducing the instances of
corrosion failures in high pressure lines and therefore ensuring a safer
working environment for
Since 2008, Nalco has sold in excess of 17,000,000 kg of the product to
over 300 customers
including many of the super-major and major oil companies around the
world. In the 5 years since
2008, the Clean n Cor technology has been Nalco's fastest growing new
product. The success of
the original product has prompted several additional derivative products
utilizing the Clean n Cor
technology to address more specific niche applications.
Clean n Cor has been used extensively at over 300 oil production
locations worldwide, to impart
corrosion protection in aging production infrastructure and to maximize
water injectivity, with the
following economic and other benefits:
- Clean n Cor is injected into fluids at very low concentrations of the
active materials (40 - 100
ppm) which ensures the application is extremely cost-effective.
- From a corrosion control perspective, the technology allows operating
companies to utilize
lower cost steel alloys for the fabrication of injection systems thereby
reducing capital costs
- Clean n Cor also protects against corrosion from naturally occurring
microbes in the system,
minimising impact to the environment and protecting personnel in
oilfield operations. More
specifically Clean n Cor helps to minimize the deposition of solids
build up in the production
infrastructure and provides the protective film that mitigates
corrosion. Minimizing the effects of
corrosion results in less failures, and ultimately safer working
conditions for employees.
- Oil companies often operate in environmentally sensitive areas and the
corrosion protection will ensure the potential for pipeline failures and
the resulting exposure of
production fluids into the environment is minimized. This in turn
assists oil and gas companies
in preserving their licence to operate and protecting their corporate
- Maximizing water injectivity has a dramatic impact on increasing oil
and gas production and this
is critical today as the global demand for oil and gas approaches the
global supply curve. By
cleaning the hydrocarbon based deposits that build up in injection
systems, the injection
differential pressure into the formation is reduced therefore allowing
more water to be injected to
balance crude oil production and ensure reservoir production pressure is
maximized. This has
resulted in increases of oil production that ranges between 50 - 100%.
- Clean n Cor also minimizes operational costs that otherwise would be
incurred through having
to clean out injection wells as they start to plug up over time. This is
not only a savings in
operational cost, but also a safety advantage. The cleaning process
involves the use of heavy
machinery and employees operating on highly pressurized flow lines.
Clean n Cor helps to keep
the pipes clean chemically as opposed to manually.
To date, there are no other competing technologies to Clean n Cor in
the oilfield market place.
Although commercial sensitivity limits the range of specific impact
details that can be given here,
however the significance of this development and the important role
played by Hull researchers
was marked by the presentation by Nalco of a plaque to the Department of
Chemistry, University of
Hull in December 2011. The award is "for collaboration in the area of
Surfactant Science that led to
the successful development of Clean n Cor".
Sources to corroborate the impact
[A] Vice President, Research and Development, Energy Services at Nalco
— corroborating the
economic impacts of Clean n Cor for the company since 1st January
[B] A break-through technology for maximizing water injectivity and
asset integrity — SPE
Production and Operations, #108675, May 2009 - corroborating the
benefits of the Clean n
[C] Integrity control in heavily fouled systems - Phase II -
Environmentally sustainable solutions - D.I. Horsup, R. Meyer, L.
Tiwari, T. Dunstan - NACE 2008, Paper #08623 - corroborating
the benefits of the Clean n Cor technology.