The Centre is currently running
a number of collaborative Government and Industry sponsored
gas hydrate research projects, as detailed below.
In addition to major projects, the centre continues to provide
individual consultancy on flow assurance issues to major hydrocarbon
production and support companies. Past and current clients
include: Shell, BP, BG, Lasmo, Marathon, Baker-Hughes
Inteq, E. Wood Ltd, Costain, CMPT, Genesis Oil and Gas, TOTAL,
Messer UK Ltd., Occidental Petroleum, Maersk, Sasol Gas, Castrol, Baker Petrolite, Rhodia, Blackwatch
Petroleum Services Ltd & etc.
If you are interested in the work of the Centre, or wish
to be involved in a project, please contact the Principal
Investigator and Research Director, Prof. Bahman Tohidi.
New sponsors may be accepted into ongoing projects at any date following consultation with current sponsors. For active proposals (e.g. the project has not started or just recently begun), please see the project proposals page.
Gas Hydrates and Flow Assurance
The Groups’ longest running Joint Industry Project (JIP) addresses mainly thermodynamic issues associated with gas hydrates. In previous phases of this JIP, gas hydrate phase equilibria for various fluid systems (i.e., single, double and multi-component systems; synthetic and real gas, condensate and oil systems) have been 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.
The investigation has covered the inhibition characteristics of various alcohols, salts, and combinations of salts and alcohols. A new technique for the optimisation of Kihara potential parameters was developed, with the resulting predictions validated against in-house and literature experimental data. In further phases of the project, the hydrate inhibition characteristics of various salts and organic inhibitors used in drilling and completion fluids were investigated, including salt solubility and salting-out problems. Again, large quantities of new experimental data were generated, and further improvements were made in thermodynamic modelling, with salts being treated as pseudo-components in the Equation of State, enabling salt precipitation prediction. An integrated wax-hydrate model was also developed.
Accompanying studies of wax experimental data and modelling approaches revealed a widespread dependence on Wax Appearance Temperature (WAT) data, which do not necessarily represent equilibrium conditions. To combat this problem, in-house step-heating techniques were extended to wax measurements using Quartz Crystal Microbalance (QCM) technology, and large quantities of experimental data on equilibrium Wax Disappearance Temperatures (WDT) were generated for various real and synthetic systems. A new thermodynamic approach for wax modelling was also developed, with promising results. The current phase of the project, which began in December 2005, covers various topics, including:
Gas hydrates in low water content gases
Transportability of water/oil mixtures and natural hydrate inhibition
Hydrate equilibrium measurements for multi-component systems, including oil systems at very high pressure conditions (up to 2000 bar)
Inhibitor distribution in water and hydrocarbon phases
Wax equilibria and wax inhibitors
Gas hydrates in water-flooded oil reservoirs
Hydrates and associated phase equilibria database
Micro and Macro-Scale Evaluation of Low Dosage Hydrate Inhibitors
Research in this area began in 2000 with a three-year EPSRC grant. This joint project with the University of Warwick resulted in the development of new experimental equipment and LDHI test procedures. The EPSRC project was followed by a JIP where high pressure glass micromodels were used for investigating gas hydrate formation and inhibition at the micro-scale, with results being up-scaled to high pressure kinetic rig tests. In the previous phase of the project, several base chemicals, synergic materials and commercial LDHI formulations were investigated using an array of novel experimental techniques, including ultrasonic methods. LDHI compatibility with scale and corrosion inhibitors was also investigated. A new phase of the project, due to start on 1 May 2006, will address the following topics:
Effect of condensate, methanol, and salt on the performance of KHIs (Kinetic Hydrate Inhibitors)
KHI compatibility with other additives/inhibitors (e.g., corrosion, scale inhibitors)
AA (Anti-Agglomerate) evaluation for high water cut systems and sub-zero conditions
KHI performance under low degrees of subcooling and high induction times
Developing new testing techniques for KHI and AA evaluation
Designing KHI formulations for structure-I hydrates
Development of environmentally friendly ‘Green Inhibitors’
Flow Assurance: Hydrate Monitoring and Early Warning Systems
Currently, hydrate inhibitors are injected at the upstream end of pipelines, based on the calculated/measured hydrate phase boundary, water cut, worst pressure and temperature conditions, and the amount of inhibitor lost to the non-aqueous phases. In general, no means of controlling and monitoring are available along the pipeline and/or downstream to assess the degree of inhibition. In many cases, high safety margins are used to account for the uncertainties in the above parameters and minimise the gas hydrate risks. However, despite all these efforts, hydrates do form that can have considerable economic and safety impacts.
The main objectives of this project are: (1) developing methods for determining the hydrate safety margin, and (2) developing techniques for detecting initial hydrate formation in pipelines. The first goal is to ensure that the system is adequately inhibited against hydrate formation and that inhibitor injection is optimised. The second goal is to develop a warning system should hydrate start to form (prior to hydrate build up and pipeline blockage). The feasibility phase of this project began in early 2004 with support from a major E&P company with promising results. The current phase of the project, with support from 7 major oil and gas production companies, began in August 2005 for a period of two years.
Wellbore Integrity in Hydrate Bearing Sediments
With the petroleum industry endeavouring to develop oil and gas fields in increasingly deeper waters, greater emphasis should be placed on quantifying the hazards to drilling operations posed by gas hydrates. The most significant risks are dissociation of gas hydrates, wellbore collapse, uncontrolled gas release and blowouts, all of which carry serious safety and economic consequences. This is a joint project with CSIRO Petroleum Australia with support four major E&P companies. The project is an integrated experimental and modelling effort with associated field evaluations.
Cold Flow: Avoiding Gas Hydrate Problems
Currently under investigation is a new concept where hydrates are not prevented from forming, but instead growth is encouraged, and solid hydrates are transported as stabilised slurry (i.e. Cold Flow). Additives may be used to control the hydrate crystal size and prevent agglomeration/potential hindrance to slurry flow. This Cold Flow approach could have the following advantages:
Eliminate the risks of hydrate blockage during normal operation, shut-in and start-up
Reduce pipeline coats by eliminating the need for insulation and/or active heating
Reduce the risk of wax deposition and blockage
Reduce/eliminate the risks and costs associated with slugging
Potentially reduce/eliminate inhibitor costs
Potentially increase pipeline capacity and reduce operating pressures
Produce hydrates ready for transportation (or for dissociation to recover gas)
This project, which began in September 2005 for a period of two years, is being supported by the Scottish Enterprise Proof of Concept Programme. Some aspects of the work are still confidential and cannot be disclosed at this stage.
Can CO2 hydrate formation act as a safety factor for subsurface storage of CO2?
CO2 is now recognised by the majority of scientists as the main greenhouse gas responsible for global warming. It is believed that in the short to medium term, fossil fuels will remain the principal source of the World’s energy. Therefore, carbon capture and storage (CCS) is likely to be essential for reducing the chances of potentially catastrophic global climate changes in the future.
This project looks into the potential role of hydrates in CO2 storage in offshore environments. Depending on the sediment temperature, CO2 can form gas hydrates at water depths greater than 200 m. Therefore, any CO2 escaping from geological storage structures could be converted into hydrates in seafloor sediments, providing an additional seal and safety factor against any CO2 leakage to ocean/atmosphere. If proved, this could provide a further criterion for choosing suitable disposal sites and help improve public acceptability. This is a three-year EPSRC supported project started on 1 March 2006.
Capillary controls on gas hydrate growth and dissociation in synthetic and natural porous media
The aim of this work is to determine the relationship between pore size, geometry, capillary pressures and gas hydrate growth and dissociation conditions in synthetic and natural porous media, and to assess the extent to which capillary inhibition is a factor in seafloor/permafrost hydrate systems. The specific objectives are:
To clarify the origins of the observed hysteresis between hydrate growth and dissociation in porous media
To investigate the effect of free gas in the pore space
To explore the effects of wettability (hydrophilic versus hydrophobic pores)
To quantify the relationship between confining stresses and capillary inhibition for unconsolidated media
To extend an existing thermodynamic model to the prediction of hydrate growth and dissociation behaviour in porous media based on pore size distribution (PSD) and pore geometry data.
The project, started on 1 February 2006 for a period of three years, is being supported by the EPSRC.
Experimental investigations of composition, structure and formation of gas hydrates in sediments
This an EU INTAS project, started in April 2004 for a period of 3 years, in collaboration with GZG Abt. Kristallographie University of Göttingen, Germany, Ecole de Mines Sainte Etienne, France, Moscow State University, Moscow, Russia, and VNII GAZ, Russia. The main aim of the project is to develop physically realistic models of the formation and decomposition of gas hydrates in natural sediments. This model will be based on experimental laboratory work combined with physico-chemical modelling.
Centre for Flow Assurance Research (C-FAR)
This a infrastructure grant from Scottish Higher Education Funding Council for building a low temperature laboratory and Flow Loop for Flow Assurance studies, in particular gas hydrates and wax. The plan is to use the low temperature laboratory for other gas hydrate studies, including gas hydrates in sediments, and gas hydrates for storage and transportation of energy. The project started in April 2006 for a period of two years.
The experimental equipment, in the two well-equipped hydrate laboratories, consists of more than 25 experimental rigs for investing various aspects of gas hydrates and flow assurance, including:
Eleven autoclave type reactors with stirrers and torque measuring capabilities for measuring hydrate phase equilibria, kinetics of hydrate formation/dissociation, and evaluation of kinetic hydrate inhibitors/anti-agglomerants over a wide range of temperature and pressure conditions (-60 C to +70 C, up to 10,000 psia). Two of the above rigs have visual capabilities, whilst 4 others are constructed of either titanium or hastelloy, allowing work with corrosive systems (e.g. when salts are present). One of the above rigs is equipped with ultrasonic transducers for investigating the effect of various chemicals on gas hydrate kinetics and crystal size/morphology. This set-up also has Quartz Crystal Microbalance facilities for investigating water condensation and/or gas hydrate formation.
Two rocking cells, with pressure ratings of 10,000 and 30,000 psia, for investigating hydrate phase equilibria and kinetics for various fluid systems. The low pressure cell is equipped with a quartz glass tube for visual observation.
Two glass micromodel set-ups, with pressure ratings of 1200 and 6000 psia, for visual observation of gas hydrate formation, dissociation and distribution at the microscale. These rigs are predominantly used for investigating gas hydrate formation in porous media and/or the effect of various chemicals on gas hydrate crystal size and morphology.
One porous media rig (6000 psia) for investigating the effect of pore size, saturation and wettability on gas hydrate phase boundary and the kinetics of gas hydrate formation in sediments.
Three ultrasonic rigs (6000 psia) for investigating hydrate formation in various natural and synthetic sediments. Each rig has one moving and one stationary piston to simulate various overburden pressures and for assessing the effect of hydrate formation/dissociation on sediments’ geomechanical properties. The rigs are used to simulate various hydrate production scenarios.
One visual wax-hydrate cell (7500 psia) for investigating wax and hydrate phase boundaries as well as effect of wax on hydrates and vice versa. The set-up is equipped with quartz crystal microbalance and pendant drop for measuring wax phase boundary and interfacial tension between various phases respectively.
Three other blind wax-hydrate cells (up to 6000 psia) with Quartz Crystal Microbalance set-ups for wax or hydrate studies.
One multiple cell (10 cells), high pressure (6000 psia) rocking set-up for investigating the performance of kinetic hydrate inhibitors.
Two variable volume, rocking cells for various phase equilibrium studies.
The majority of experimental equipment is designed and built in-house. Recently, the Group have built a number of experimental set-ups for major operators and other research institutions. The Centre is equipped with various other experimental support facilities, including:
Freezing point measurement equipment
Boiling point measurement set-up
Solubility and salting-out measurement set-up
ASTM Cloud point determination set-up
GC and GC/MS facilities
Gas volume and flow meters
High accuracy Quizix and other high pressure pumps
Recently Completed Projects
Gas Hydrates in the Natural Environment
Start Date: February 2001 Completion Date: January 2004 Duration: 3 years
Research into naturally occurring
clathrates in sediments forms a major part of work at the
Centre. Studies in this area are currently funded by the Scottish
Higher Education Funding Council (SHEFC) through a Research
Research combines advanced experimental and modeling studies
aimed at addressing many of the important issues regarding
hydrates in the natural environment. Work currently focuses
Sedimentological controls (pore
size, mineralogy, wettability, gas/liquid saturation) on hydrate
growth and dissociation kinetics, thermodynamic stability,
and phase distribution.
Detection and quantification
of hydrates in sediments - acoustic properties of sediments
hosting hydrates and seismic interpretation.
Evaluation of methane exploitation
and CO2 sequestration schemes.
Hydrates as a geohazard - danger
to deepwater hydrocarbon drilling and production operations,
hydrates and subsea slope stability.
Novel visual studies of clathrates
at the pore scale using glass micromodels.
and Testing of Low Dosage Hydrate Inhibitors for Use in the
Offshore Oil and Gas Industry
Start Date: November
2000 Completion Date: November 2003 Duration: 3 years
Collaborative project with the
University or Warwick. Warwick utilise computer simulations
to design and manufacture new compouds for assessment as low
dosage hydrate inhibitors. Centre for Gas Hydrate Research
responsible for testing and evaluation of inhibitor effectiveness
in hydrate control and prevention in oil and gas production