CBET-EPSRC: Enhancing the CSMHyK fluid dynamics calculations via the inclusion of a stochastic model of hydrate nucleation, agglomeration and growth

Lead Research Organisation: University College London
Department Name: Chemical Engineering

Abstract

Sir Humphrey Davy discovered clathrate hydrates in 1811. Hydrates are solid structures formed by water and gases, e.g., methane. The abundance of natural gas hydrate deposits across the world could provide abundant energy resources for the future, as well as long-term CO2 storage. Natural gas hydrates can be exploited in high-tech applications including innovative water-desalination and gas-storage processes. Prof. Carolyn Koh overviewed hydrates in the book she co-authored with Prof. Dandy Sloan: Clathrate Hydrates of Natural Gases, 3rd Ed., CRC Press, 2007.

This proposal is concerned with hydrate plugs in oil & gas pipelines. Such plugs can lead to pipelines ruptures, causing spills and environmental disasters, production interruptions, and even loss of life.
The traditional approach to manage hydrates is adding thermodynamic inhibitors (THIs), e.g., methanol. THIs shift the conditions at which hydrates are stable to lower Ts and higher Ps. However, large amounts of THIs are necessary, which negatively affects both the economics of the operations and their environmental impact. Among emerging promising technologies to prevent hydrates formation in pipelines is the use of 'low dosage hydrate inhibitors' (LDHIs), effective at low concentrations.

Among other limitations, the wide applicability of LDHIs is impeded by a current lack of understanding of how LDHIs function. In fact, LDHIs performance depends on oil composition, water salinity, temperature, etc. LDHIs include kinetic hydrate inhibitors (KHIs) and anti-agglomerants (AAs). This timely project will develop a fundamental understanding regarding how AAs function.

The project builds on significant prior results. For example, Prof. Koh and her group produced extensive experimental data regarding the performance of LDHIs, and developed extensive experimental characterisation capabilities to probe AAs at different length scales (from the microscopic, using micromechanical force measurements, to the macroscopic, using flow loops). Prof. Striolo employed molecular simulations to discover possible molecular mechanisms that are responsible for the performance of LDHIs (in particular, AAs). The simulation results led to new LDHIs formulations, environmentally benign, recently disclosed in a patent application.

To widely adopt LDHIs, it is required to develop reliable models that accurately describe the likelihood of hydrate plugs formation as a function of process conditions. This project will transform the pioneering software CSMHyK, which is already coupled with the industry-standard multiphase flow simulator OLGA. CSMHyK (1) describes accurately multi-phase transport in pipelines; (2) uses reliable equations of state to predict the hydrates thermodynamic stability; and (3) employs working assumptions to predict hydrates formation. To enable the latter feature, an important parameter is the nucleation sub-cooling, which is treated as an input parameter currently estimated from experimental flow-loop results, thus lacking predictability.

To render CSMHyK predictive, it is proposed to develop a model, based on kinetic Monte Carlo (KMC), to describe quantitatively the hydrate population dynamics as a function of system conditions. The new model will allow practitioners to quantify LDHIs' effects, which is currently not possible, as well as to include molecular-level information from microscopic experiments and molecular simulations into the formulation of risk assessment.

This NSF-EPSRC Lead Agency Agreement proposal builds on an Expression of Interest submitted to EPSRC on 04/08/2018, which was approved on 19/09/2018. The project benefits from strong industrial interest, and from established collaborations. The collaboration between Striolo and Koh was enabled by their industrial partner Halliburton and by a Royal Society International Collaboration grant. Striolo and Stamatakis collaborate in a project in which KMC was implemented to study fluid transport.

Planned Impact

This project will deliver:
1. Fundamental understanding of the molecular mechanisms responsible for hydrates agglomeration and growth, in the presence of surfactants used as anti-agglomerants (AAs), by combining seamlessly state-of-the-art experiments and molecular modelling. This will benefit primarily the academic community, which will be addressed via conference presentations, peer-reviewed journal articles, as well as workshops at the Thomas Young Centre.

2. Identification of the rate-limiting steps in the process of hydrate plugs formation by the implementation of an innovative stochastic kinetic Monte Carlo (KMC) approach applied to hydrates. This is a fundamental advancement, which will benefit primarily the academic community, but also the industrial community, especially those entrepreneurs who are investing in new technologies for, e.g., natural gas intermittent storage in hydrates, water desalination using hydrates, and CO2 sequestration using hydrates.

3. A potential game-changing improvement on the CSMHyK fluid dynamics simulation package, via the incorporation of a KMC model to quantify the probability of hydrates plug formation as a function of P&T conditions. Because CSMHyK is already coupled with the industrial standard multiphase flow simulator OLGA, our model will allow industry to quantify and reduce risks. Primary beneficiary of this impact will be the industrial energy sector. Note that oil and gas operations in the North Sea will particularly benefit, should this project contribute to develop hydrate-mitigation strategies that are successful. To enhance impact, frequent presentations at industrial consortia (in particular the Centre for Hydrates Research at the Colorado School of Mines), and productive collaborations with our industrial partners will be conducted. A workshop at the Thomas Young Centre (see letter of support) will also help positively influence the industry at large.

4. Technology transfer to UK and US industry partners via the demonstration of the capabilities of the new software. We have prior experience: MS developed Zacros, a code that is the result of 7+ years of research and software development efforts. Zacros, distributed by UCL Business, has been licensed to more than 300 non-UCL users worldwide. The workshop at the Thomas Young Centre will be instrumental for enhancing this positive impact.

5. Training of 3 PDRAs and 3 Ph.D.s in state-of-the-art modelling and experimental protocols. Critical is that these researchers will be trained in multi-disciplinary approaches, and will be exposed to both academic and industrial environments. Note that 2 of the 3 Ph.D. students will be supported by industrial collaborator Halliburton.

6. Attraction and inclusion of under-represented minority students in STEM disciplines, via a range of activities that target students at all stages of development. This will help the project positively affect the public at large, which will also be reached via informed documentations in our websites, inclusion of the research results in the material we teach in classrooms, and publication of dissemination articles.
 
Description The project is now completed. The combination of computational research conducted by Striolo and Stamatakis, and the experimental results obtained by Koh (at the Colorado School of Mines) has led to significant key fundamental findings:
1. Excellent agreement has been obtained between numerical and experimental approaches implemented to screen potential surface active chemicals used to prevent the formation of hydrate plugs in pipelines. The simulations allowed us to understand the mechanisms by which they work. The agreement with experiments has strengthen our interpretation.
2. A workflow has been proposed to aid the discovery of new surface active chemicals to be used as anti-agglomerants. The main advanage is that the experimental work can be focused only on promising candiates, reducing costs and time required to innovate the field.
3. Excellent agreement has been obtained between modelling (Striolo and Stamatakis) and experiments (Koh) regarding the wettability of hydrate particles in the presence of various types of oils. This settled a disagreement in the literature, identifying in the line tension and surface roughness the reason for the differences. This allows for a better fundamental understanding of the driving forces that can lead to hydrate plugs formation in pipelines and elsewhere, with the potential of reducing the environmental footprnt of the energy sector.
4. Experimental observations, supprted by modelling results highlighted new mechanisms by which hydrates grow, in particular via the formation of surface structures. Tgis has potential importance for understanding adhesion of hydrate particles on various substrates, which is relevant for safety.
5. A stochastic model has been developed to describe hydrate growth. The model takes into consideration atomistic results, and is able to quantify the morphology of hydrate particles formed under various degrees of sub-cooling. The results could allow for enhancements of the capabilities of the CSMHyk software.
6. A new algorithm has been proposed to describe hydrate growth at the three-phase boundary (hydrate, liquid, and gas). This algorithm allows for a more realistic description of the phenomena under consideration.
7. We were able to identify conditions at whoch synergistic and antagonistic effects appear when anti-agglomeramts and other production chemicals are used simultaneously. This has the potential of identifying conditions when CO2 hydrate growth can be promoted, while simultaneously stabilizing said hydrates. This was only possible via the combination of experimental and modelling results, which was enabled by the NSF-EPSRC funding opportunity.
8. New promoters were identified for speeding up the growth of CO2 hydrates, which has the potential of opening up new venues for capturing CO2 from small emitters, transporting it, and sequestering it using hydrates.

The results are all of the fundamental type, but they also have significant opportunities for positive impact in the industry.
We are currently pursuing funding sources for continuing this project.
Exploitation Route The ability of using modelling to identify new surfactants could lead to important advancements in specialty chemicals design.
The ability to incorporate hydrate growth rates in the presence of various chemicals in CSM-Hyk has the potential of de-risking the transport of hydrocarbins.
The fundamental observations have the potential of being applicable, upon appropriate changes, to CO2 hydrates, which has potential impact in reducing the environmental impact of the energy sector.
The demonstrated ability of modelling to reproduce several experimental observations opens up vanues for attacking other important challenges in the sector, for example hydrates adhesion.
Sectors Chemicals

Energy

Environment

Manufacturing

including Industrial Biotechology

 
Description The results have been presented in the open literature, and also at a number of conferences. Perhaps the wide impact of trhe project is demonstrated by the effective collaboration with the Colorado School of Mines. The results obtained by the modeling group at UCL have been instrumental for explaining experimental findings in industry, and they have been discussed at several meetings of the Center for Hydrates Research at the Colorado School of Mines. In addition, one PDRA originally involved in the project, Dr Anh Phan, has secured a position as Lecturer at the University of Surrey, and another one, Dr Miguel Pineda, has secured a position as Lecturer at UCL. The results have been used as fouondations for several new projects. We are awaiting the decisions from funding agencies.
First Year Of Impact 2022
Sector Chemicals,Education,Energy,Environment
Impact Types Societal

 
Description Opinion manuscript in peer-reviewed journal article
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
 
Title Algorithm to study hydrate growth 
Description We expanded previous algorithms, and introduced the ability to consider the simultaneous presence of 3 interfaces 
Type Of Material Improvements to research infrastructure 
Year Produced 2022 
Provided To Others? Yes  
Impact It is now possible to consider realistic conditions when one whishes to study the growth of hydrates. This allows researchers to identify the real molecular mechanisms responsible for growth, and therefore identify new chemicals for preventing hydrates growth 
 
Title An observation on amtagonistic effects between different flow assurance chemicals 
Description Using molecular dynamics simulations we explained a discrepancy in experimental observations 
Type Of Material Improvements to research infrastructure 
Year Produced 2023 
Provided To Others? Yes  
Impact When different chemicals are used to stabilize hydrates, as well as to speed up their growth, it is possible to obtain synergistic effects as well as antagonistic efects. We explain when the antagonistic effects emerge: with the formation of micellar aggregates due to one of the surface-active chemicals. This allows to de-risk operations related to hydrate management, with impact on CO2 capture, transport and storage using hydrates. 
 
Title Interpretation of experiments using modelling results 
Description Combining experiments from CSM and modelling from UCL, we have been able to propose an hypothesis to settle a disagreement in the literature concerning the wetting properties of hydrate particles. The significance is that wetting is strongly related to the agglomeration between hydrate particles. Our insights will be useful for managung hydrates in the future. 
Type Of Material Improvements to research infrastructure 
Year Produced 2022 
Provided To Others? Yes  
Impact New research can now be designed based on our insights. This will probe the structure and mechanical properties of hydrate particles. 
 
Title New Algorithms 
Description We introduced a method, based on stochastic kinetic monthe carlo, to investigate the growth of hydrates as a function of sub-cooling conditions. This has a direct implication for CSM-Hyk, as it allows researchers to quantify how rapidly and with which morphology a hydrate particle can grow 
Type Of Material Improvements to research infrastructure 
Year Produced 2023 
Provided To Others? Yes  
Impact ths tool alows one to predict the morphology of a hydrate particle grown at non-equilibrium conditions. The surface morphology will affect how hydrate particles agglomerate. 
 
Title New algorithms 
Description We have identified a workflow for the in-silico design and initial screening of new compounds, which could be used as anti-agglomerants. The workflow has been published as a journal article. 
Type Of Material Improvements to research infrastructure 
Year Produced 2021 
Provided To Others? Yes  
Impact It is now possible to screen potential candidates in-silico befiore they are manufactured and tested experimentally. 
 
Title new algorithm to screen potential anti-agglomerants 
Description a new approach, based on molecular thermodynamics, has been proposed to screen new chemicals as potential anti-agglomerants 
Type Of Material Improvements to research infrastructure 
Year Produced 2023 
Provided To Others? Yes  
Impact One can now propose a hypothetical chemical structure and, using our algorithm, predict whether it will be an effective anti-agglomerant. This can save much experimental work. 
 
Description Center for Hydrates Research - Colorado School of Mines 
Organisation Colorado School of Mines
Country United States 
Sector Academic/University 
PI Contribution The Centre for Hydrates Research at the Colorado School of Mines has been operating for >25 years and has been supported by >$1.5M per year in funding from industry (e.g., BP, Chevron, Shell, Halliburton, StatOil and others) and government (US Department of Energy). This centre conducts cutting-edge experiments for better understanding hydrates, and how to manage them. For example, the centre has developed micro-mechanical force apparatuses for directly sampling the force between two hydrate particles. These type of experiments are at the micro-scale. Macroscopically, the centre has developed flow loops and rocking cells instruments that can be used to quantify the performance of anti-agglomerants. As such, the centre provides an arsenal of experimental capabilities for validating the simulation results achieved within AS' group at UCL.
Collaborator Contribution We have conducted simulation results for a variety of anti-agglomerants. These simulations have been used to steer the experiments conducted at the Colorado School of Mines. We are now developing a joint proposal to bring these initial collaborative studies to fruition.
Impact The proposal EP/T004282/1CBET-EPSRC: Improving CSMHyK via Molecular Modelling and Stochastic Simulations. Funding Agency: EPSRC / NSF. Funding period: three years, just announced. Amount awarded: £ 490,000 (UK) plus ~ $300,000 (US).
Start Year 2020
 
Description Chevron 
Organisation Chevron Corporation
Department Chevron Energy Technology
Country United States 
Sector Private 
PI Contribution Based on the results achieved during the EPSRC award, we have been able to establish a collaboration with Chevron. Chevorn is collaborating with the CBET-EPSRC project, as we seek to improve the CSMHyK software. In early 2020 Prof. Striolo visited Chevron in Houston, TX, USA, to discuss a new PhD studentship on a topic strictly related to the EPSRC award.
Collaborator Contribution They have provided known how to help identify the best systems to be simulated, and they have helped interpret the simulation results.
Impact One new project under development (Covid has delayed the discussion): PhD Studentship for the simulation of Anti-Agglomerants at the water-hydrate interface. One project is being negotiated related to flow assurance, but focused on asphaltenes. This is a new collaboration, wrth £400,000 over 3 years.
Start Year 2021
 
Description Chevron 
Organisation Chevron Corporation
Department Chevron Energy Technology
Country United States 
Sector Private 
PI Contribution Based on the results achieved during the EPSRC award, we have been able to establish a collaboration with Chevron. Chevorn is collaborating with the CBET-EPSRC project, as we seek to improve the CSMHyK software. In early 2020 Prof. Striolo visited Chevron in Houston, TX, USA, to discuss a new PhD studentship on a topic strictly related to the EPSRC award.
Collaborator Contribution They have provided known how to help identify the best systems to be simulated, and they have helped interpret the simulation results.
Impact One new project under development (Covid has delayed the discussion): PhD Studentship for the simulation of Anti-Agglomerants at the water-hydrate interface. One project is being negotiated related to flow assurance, but focused on asphaltenes. This is a new collaboration, wrth £400,000 over 3 years.
Start Year 2021
 
Description Institute of Applied Surfactant Research, University of Oklahoma 
Organisation University of Oklahoma
Country United States 
Sector Academic/University 
PI Contribution The modeling results have been presented to this consortium meeting, which brings together 8 companies operating in a varierty of sectors, from the energy to the personal care. The approaciation that simulation insights can be beneficial for formulating new products is stimulating new research ideas.
Collaborator Contribution Ideas are shared, with the possible outcome of including the structure of bio-derived surfactants in future formulations.
Impact A presentation was given at the IASR meeting in November 2021.
Start Year 2020
 
Description University College Dublin 
Organisation University College Dublin
Country Ireland 
Sector Academic/University 
PI Contribution Our work on hydrates has led us to establish a collaboration wtih Prof. Niall English of UCD. Bilding from a prior EPSRC project, we submitted a collaborative proposal from the EPSRC-SFI platform in 2020. Although well reveiwed, the project was not supported. We are now considering a new project, which will focus on the transport of CO2 using hydrates. We expect to submit the proposal in the summer.
Collaborator Contribution Prof. English will provide insights on hydrates dissociation as well as experimental data to support our results.
Impact Nothing yet, as we are at the discussion stage.
Start Year 2021
 
Description A presentation to the company Clariant 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact We presented the main outcomes of the modelling activities conducted within this project, and we discussed their relevance for the identification of new compounds.
Year(s) Of Engagement Activity 2021,2023,2024
 
Description Discussion with BP experts on hydrates 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Exchanges ideas on how to use the simulation results obtained so far for enhancing impact
Year(s) Of Engagement Activity 2018,2022,2023,2024
 
Description Frequent interactions with Innospec 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact The team meets regularly (every 3 months) with Innospec to illustrate the results and to align the research with the needs of the specialty chemicals sector
Year(s) Of Engagement Activity 2021,2022,2023,2024
 
Description Further Discussions with Chevron 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact A discussion took place in Houston, TX, USA, regarding the outcomes of the project, and possible follow ups.
The result was a new collaborative project, which is currently being negotiated.
Year(s) Of Engagement Activity 2019,2021,2022,2023,2024
 
Description International conference presentation at ICGH2020, which was postponed to 2023 because of COVID 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This is a conference presentation at the upcoming international conference on gas hydrates, to be held in Singapore.
The title of the presentation is:
T. Bui, Q. Lan, L. Vo, S. Bodnar, A. Striolo,* Hydrates Management Using Surfactants: A Molecular Simulation Perspective, 10th International Conference on Gas Hydrates, ICGH10, Singapore, June 21st-26th, 2020.
Year(s) Of Engagement Activity 2020,2023