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.

Publications

10 25 50
 
Description The project has been running for almost 2 years at the time of this writing. So far, we have been able to:
1. Achieve very good agreement between modelling rsults obtained at UCL and experimental data obtained at CSM regarding the performance of surfactants used to prevent the formation of hydrate plugs in pipelines. One manuscript is currently in preparation to showcase these results. This achievement shows that it is possible to use molecular modelling to screen potential new surface-active compounds to assess their ability to prevent hydrates formation. Then, the most promising candidates can be manufactured and tested. This could lead to significant savings in the costs associated with innovation in the field.
2. Results show good agreement between modelling (UCL) and experiments (CSM) regarding the wettability of hydrate particles in the presence of various types of oils. 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.
3. A stochastic model to describe hydrate growth is being developed. The results are encouraging, but we still testing the model. Soon, it will be possible to incorporate in this model the insights achieved from atomistic modeling and test the predictions against the experiments.
4. A new outcome is the description of the effect of kinetic hydrate inhibitors on the growth of hydrates. We are conducting experiments (at CSM) and modelling (at UCL) for similar systems. So far, the results show qualitative agreement.
Exploitation Route The ability of using modelling to identify new surfactants could lead to important advancements in specialty chemicals design.
Sectors Chemicals,Energy,Environment,Manufacturing, including Industrial Biotechology

 
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 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. 
 
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 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