08 - Assuring Hydrocarbon Flow with Improved Hydrate Management
Submitting InstitutionsHeriot-Watt University,
University of Edinburgh
Unit of AssessmentGeneral Engineering
Summary Impact TypeTechnological
Research Subject Area(s)
Chemical Sciences: Physical Chemistry (incl. Structural)
Engineering: Chemical Engineering, Resources Engineering and Extractive Metallurgy
Summary of the impact
ERPE research led to the following impacts in the REF2014 period:
- Extending the life of the NUGGETS field (operated by Total) by three
years with an increase in cumulative production of 2% (2.8 Million
Barrels of Oil Equivalent, value $150M).
- Saving $3-7M in costs associated with methanol removal from liquid
hydrocarbon phase by demonstrating methanol could be removed from
Natural Gas Liquids directly by molecular sieve, which played a major
role in Total's decision in eliminating a de-propaniser from "methanol
removal facilities", saving around £50M.
- Hydrafact: a start-up company with a turnover of £1M in 2012 and
employing 8 full-time and 15 part-time staff.
The key ERPE researchers throughout the period were; Bahman Tohidi
(Professor), Adrian Todd (Professor), Ali Danesh (Prof)(1986-2007), Rod
Burgass (Research Associate), Ross Anderson (Research Associate).
The most important outputs of the ERPE research were:-
- The ability to predict hydrate and water hydrocarbon phase behaviour
using the thermodynamic modelling and experimental data generated
through various research projects.
- The discovery that n-propanol takes part in clathrate formation, which
is contrary to the general understanding that alcohols prevent hydrate
formation. Consequently, n-propanol was modelled as a hydrate-forming
compound by use of a thermodynamic model.
- The examination of a statistical thermodynamic model of the phase
equilibria to predict the hydrate dissociation conditions of methane and
natural gases in the presence of distilled water or ethylene glycol
Gas hydrates form in hydrocarbon production and processing operations,
causing serious operational and safety concerns. Petroleum Engineering in
ERPE sought to understand and address various aspects of flow assurance
and gas hydrate research, and built expertise in the field of research in
Hydrate-Phase Equilibria (PVT). Areas of interest included avoiding gas
hydrate, wax and asphaltene problems in petroleum production and
transportation, design and testing of low dosage hydrate inhibitors,
hydrate monitoring and early warning systems and the natural occurrence of
hydrates in sediments.
From 1993 onwards, ERPE successfully undertook a variety of Joint
Industry Projects (JIP) and Government sponsored research projects, the
focus of which was to develop a method for avoiding hydrate problems in
offshore oil and gas operations. These projects were partnerships of up to
20- 30 industrial partners investing up to £38.5k per annum per sponsor
into the research. Grants from the ESPRC supplemented the activity from
the late 1990s, supporting research such as work on gas hydrates in subsea
sediments [G1], and rational design & testing of low dosage hydrate
inhibitors for use with offshore oil & gas production [G2], the
objective of which was to use molecular dynamics computer simulation in
conjunction with carefully designed experiments to identify the molecular
mechanisms by which low dosage hydrate inhibitors (LDHIs) work and thereby
to design and synthesise new LDHIs for use in the petroleum industry.
The Group's longest running JIP, Gas Hydrates and Flow Assurance,
investigated thermodynamic issues associated with gas hydrates. This work
examined the relationship between pore size, geometry, capillary pressures
and gas hydrate growth and dissociation conditions in synthetic and
natural sediments and the potential hazard hydrate destabilisation could
pose to deep-water oil/gas platforms, pipelines and subsea cables, and
long-term considerations with respect to hydrate stability, methane (a
potent greenhouse gas) release to the atmosphere, and global climate
changes. In previous phases of this JIP, gas hydrate phase equilibria for
various fluid systems (i.e., single, binary and multi-component systems;
synthetic and real gas, condensate and oil systems) were studied,
resulting in the generation of a large quantity of novel experimental data
on hydrate dissociation conditions and the amount and composition of
various phases under equilibrium conditions.
Over the course of the period 1993 to 2013, the team firmly established
itself within the industrial and academic communities as a leader in flow
assurance research, with a reputation for quality experimental work and
advanced theoretical studies. Sequential JIPs have supported the
generation of a large in-house library of hydrate equilibrium data, and
development of the commercial hydrate predictive software such as
HydraFLASH® was developed as the most accurate software for
predicting hydrate and water hydrocarbon phase behaviour using the
thermodynamic modelling and experimental data generated through various
research projects used by major hydrocarbon production and service
companies, such as Total, BP and Statoil, in planning their flow assurance
References to the research
The references identified with * are the ones which best indicate the
quality of the underpinning research.
 * Tohidi, B., Danesh, A., and Todd, A.C., "Modelling Single and
Mixed Electrolyte Solutions and its Applications to Gas Hydrates", Chemical
Engineering Research and Design, 73A pp. 464-472 (1995).
This paper contributed to the development of HydraFLASH® the
most accurate software for predicting hydrate and water hydrocarbon phase
behaviour using the thermodynamic modelling and experimental data
generated through various research projects ISSN: 02638762. 75 Google
Scholar (GS) citations. Available on request
 * Chapoy, A; Anderson, R; Haghighi, H; et al. "Can
n-propanol form hydrate?" Industrial & Engineering Chemistry
Research Volume: 47, Issue: 5, pp: 1689-1694 2008 DOI: 10.1021/ie071019e.
21 GS citations
The publication made industry aware of hydrate characteristics of
n-propanol and iso-propanol and provided the necessary information for
modelling using other software.
 Yang, J; Tohidi, B "Determination of Hydrate Inhibitor
Concentrations by Measuring Electrical Conductivity and Acoustic
Velocity" Energy & Fuels, 2013 Volume: 27, Issue: 2, pp: 736-742
This is the basis for HydraCHEK® (one of Hydrafact's Products)
which can determine the amount of salt and hydrate inhibitor and determine
the hydrate safety margin.
 Mohammadi, A, Chapoy, A.,.H., Richon, D and Tohidi, B., "Experimental
Measurement and Thermodynamic Modeling of Water Content in Methane and
Ethane Systems", Industrial and Engineering Chemistry Research, 2004,
Vol. 43, No. 22, pp. 7148-7162. DOI: 10.1021/ie049843f
41 GS citations
Experimental data generated in this work was compared with predictions of
the HydraFLASH® thermodynamic model as well as other predictive
methods. The results of this project were used in improving and validating
HydraFLASH® predictions for low water content systems.
[G1] EPSRC, GR/N06724/01, £212k, Tohidi, Danesh, Todd. "Rational
Design & Testing Of Low Dosage Hydrate Inhibitors For Use With
Offshore Oil & Gas Production" 2000-2003. The identification of
the molecular mechanisms by which low dosage hydrate inhibitors (LDHIs)
work to inform synthesis of new LDHIs for use in the petroleum industry.
[G2] EPSRC, EP/D052556/1, £286k, Tohidi, Anderson "Capillary controls
on gas hydrate growth and dissociation in synthetic and natural porous
media: PVT, NMR, Neutron Diffraction and SANS 01" 2006-2009. An
examination of the relationship between pore size, geometry, capillary
pressures and gas hydrate growth and the potential hazard hydrate
destabilisation could pose to deep-water oil/gas platforms, pipelines and
[G3] EPSRC, EP/D013844/1, £297k, Tohidi, "Can CO2 hydrate formation
act as a safety factor for subsurface storage of CO2?", 2006-2009.
Worldwide occurrences of methane gas hydrates (comparable to total fossil
fuels) inspired scientific investigation of the ways to recover this
resource of low-carbon energy. The main recovery methods proposed include
depressurization, thermal stimulation, inhibitor injection, or various
combinations of these.
[G4] EPSRC, EP/E04803X/1, £412k, "Towards Zero Carbon Emissions:
Novel Low Pressure Molecular Natural Gas/CO2/H2 Storage and Separation
using Semi-Clathrates" 2008-2011. Assessment of the potential of
hydrate formers through an intensive integrated experimental and
theoretical study to support the global energy industry.
Details of the impact
The Centre for Gas Hydrate Research was formed in 2001 and the Centre for
Flow Assurance Research established in 2007. The Centres have generated
circa £10M since 2001 from industry in research projects. The data
generated in numerous research projects was used in development and tuning
of accurate thermodynamic modelling.
Total has extended production from the NUGGETS reservoir that was to be
abandoned in 2010. So far they have produced an extra 2.8 million Barrel
of Oil Equivalent (BOE) of gas increasing the recovery factor by 2% (and
generating around $150M additional income at a gas price of $11 per MMBtu
(Million British thermal units)). [S4, S7] They are still producing and
plan to continue production for several more years. Using ERPE IP and
HydraCHEK®, they have not only extended the life of the
reservoir, but reduced the methanol injection drastically. Currently they
have completely stopped methanol injection (from the designed 28%) and
control the hydrate slurry concentration by HydraCHEK®.
Reducing/eliminating the methanol injection rate has several important
consequences, including; reduction of the use of expensive toxic
chemicals, reduction/elimination of methanol contamination in the produced
condensate and improving the management of a highly toxic and flammable
compound and the associated environmental impact.
Total have also made changes to the design of methanol removal from NGL
facilities, using Hydrafact test results and ERPE knowledge to demonstrate
that a depropaniser could be removed from the design, saving around £50M.
Total has obtained a significant reduction in methanol injection rate
from the designed 28 wt% to less than 3 wt%, saving around £1-5M per year
and eliminating disposal of around 28,000 m3 of methanol per
year using one of Hydrafact's products, HydraCHEK®. HydraCHEK®
is a lab based analytical tool that measures the concentration of hydrate
inhibitor and salt in produced water samples taken from a pipeline .
Total state "The C-V technique (HydraCHEK®)
has allowed North Alwyn to rapidly monitor the degree of hydrate
inhibition present in the NUGGETS produced waters at reception
facilities, leading to an increased confidence in optimising the hydrate
In 2005 the University decided to form a spin-out company to exploit the
commercial opportunity. Hydrafact (founded in 2006) has grown during the
REF period to employ 23 staff (8 full-time and 15 part-time staff) and has
3 key products, laboratory facilities, hydrate blockage management
services and experimental services with a turnover of £1M in 2012.
Hydrafact has delivered more than 135 projects to 77 companies in 26
countries across a range of specialisms such as complex and unusual flow
assurance challenges for the transportation of oil, gas and multi-phase
products. [S8] The benefits of working with Hydrafact are described by a
Senior Specialist, Flow Assurance at Statoil: "Several... projects...
related to acquisition of high quality experimental equilibrium data of
fluid systems are critical for Statoil's operation. The results have
been invaluable for our operation enabling Statoil to optimise our
operation within the relevant area covered by these studies. It is
difficult to substantiate the value of these results due to the
complexity of the system. It suffices to state that without these
results our operations would be non-optimal resulting in lost value in
tens of millions Norwegian Kroner (hundreds of thousands of GBP) per
Companies such as BP, Total, Schlumberger, Statoil and Petrobras are
repeat customers that routinely commission Hydrafact to solve their flow
assurance problems, increase production, extend the life of wells and
fields and provide training to their own teams. All of these activities
transfer knowledge developed in ERPE to the companies. As a Flow Assurance
Chemist from Petrobras stated, "Flow assurance imposes a significant
challenge for our deep-water off-shore oil production developments. The
knowledge and procedures created... contributed significantly to
optimise the design of our subsea systems and reduce production losses
due to flow assurance issues, mainly gas hydrates pipeline blockage".[S2]
Sources to corroborate the impact
[S1] Senior Specialist Flow Assurance, Statoil. Regarding acquisition of
high quality experimental equilibrium data of fluid systems critical for
Statoil's operation. The results were invaluable to enable Statoil to
optimize operation within the relevant fields.
[S2] Flow Assurance Chemist, Petrobras Will confirm that Petrobras uses
the research to optimise the design of subsea systems to tackle mainly gas
hydrates pipeline blockage
[S3] Senior Development Engineer, TOTAL E&P UK Limited Will
corroborate the impact of removal of methanol from NGL directly by
molecular sieve, which played a major role in Total's decision in
eliminating a de-propaniser from "methanol removal facilities", saving
around £50 million.
[S4] Team Leader - Production and Site Support, Total E&P UK Ltd Will
describe how the research was instrumental in extending the life of the
NUGGETS and how it led to increased cumulative production of 2%+ . Will
also talk about savings generated costs associated in removing methanol
from liquid hydrocarbon phase.
[S5] NUGGETS Gas Field - Pushing the Operational Barriers SPE
Paper 166596, available on request. DOI: 10.2118/166596-MS
The paper confirms on page 10 that Total used the Hydrachek tool to inform
their hydrate management strategy.
[S6] "Successful Deployment of a Novel Hydrate Inhibition Monitoring
System in a North Sea Gas Field". MacPherson et al, at 23rd
International Oil Field Chemistry Symposium, 2012. http://www.tekna.no/ikbViewer/Content/832455/Oil%20Field%20Chemistry%20-%20Final%20program%202012.pdf
Provides the rationale for the calculations on generating income through
extending the life of the NUGGETS field.
[S8] www.hydrafact.com describes
the products developed by the research in detail