Dear Sayyed,

The following publications demonstrate the use of molecular dynamics simulation for application in sea industries:

1-Molecular dynamics simulations on the inhibition of methane hydrates

by Zhiju Zheng

Gas hydrates are ice-like solids consisting of polyhedral water cages surrounding gas molecules. They are formed at low temperatures and high pressures, which are also the conditions found in deep oceans. When gas and oil pipelines are constructed on ocean floors, gas hydrates can form when undesired water enters the pipeline. Once the hydrates agglomerate, the resulting plugs block the gas flow, leading to pipeline rupture and serious accidents that are economically

and ecologically expensive. The gas and oil industries have long been concerned about this problem. One approach to suppressing the problem of hydrate buildup is through the use of thermodynamic inhibitors, which shift the formation conditions of hydrates to temperatures and pressures where hydrate is not stable. However, this method requires a large amount of the inhibitors so that their use incurs high costs and carries a significant environmental risk. Another way to prevent the formation of hydrate plugs is to add low dosage hydrate inhibitors (LDHIs) which are effective at concentrations as low as 1 wt% of water. LDHIs are usually water soluble polymers and act by delaying hydrate formation or preventing agglomeration of hydrate crystals. As to the exact action mechanism by which LDHIs work, little is known,

which limits the improvement and application of this type of inhibitor. The drive to develop more active and robust inhibitors for the oil industry has inspired a wide range of research in this field. Computational modeling has been shown to be a valuable tool to study the initial growth of hydrates as well as the effect of inhibitors on the growth of hyrates, understand the inhibition mechanism at a molecular level, and help to develop new inhibitors. Among the various types of LDHIs, a class of hyperbranched poly(ester amide)s (tradename Hybrane) has been shown particularly effective at controlling the formation and growth of gas hydrates. This kind of inhibitor is biodegradable, nontoxic to the sea organisms, and easy

to separate from the oil in the pipelines. These advantages make them good candidates as inhibitors for assuring good flow in pipelines. The goal of this thesis is to provide a molecularbased insight on the inhibition behavior of Hybrane molecules on the growth of methane hydrates. The growth of methane hydrates is studied using molecular dynamics simulations. It is rather difficult for the nonpolar gas molecules and the polar water molecules to form a stable crystal, owing to the poor mixing of methane and water molecules. Our model system contained

a slab of methane hydrate crystallite and a fluid methane/water mixture. The crystallization process involves the self-ordering of water and methane molecules at the interface of hydrate and fluid. The results show that hydrate crystallites have successful growth at both interfaces. Hybranes with two different molecular weights are inserted into the system to examine the effect of inhibitor size on the growth of methane hydrate. The molecule with higher molecular weight shows the inhibition effect, while one with lower molecular weight does not control the growth of hydrate. The molecular weight has not previously been considered when studying

hydrate inhibitors using molecular modeling. Thus, this work opens a new insight into the effects of inhibitors. The remainder of the thesis is organized as follows. Chapter 2 provides a brief overview of gas hydrates and hydrate inhibitors, and Chapter 3 introduces molecular dynamics as a simulation method. Chapter 4 contains a detailed account of the simulations conducted on Hybrane LDHIs. This chapter is based on a manuscript in preparation for submission to The Journal of Physical Chemistry. The final chapter outlines possible plans for future work.

To view the whole publication, please see attached file.

2-Applications of Molecular Simulation in Oil and Gas Production and Processing

Abstract — Applications of Molecular Simulation in Oil and Gas Production and Processing —Molecular simulation is an emerging technique which consists in performing a detailed simulation of microscopic systems involving typically a few hundreds of molecules. On the basis of these simulations, appropriate statistical averages are performed to derive fluid properties that can be compared with

experimental measurements. The purpose of the article is first to provide the reader with basic notions of molecular simulation. Then, application examples are given in several fields of the oil and gas industry. In reservoir engineering, the examples relate to the properties of poorly known hydrocarbons, the thermal properties of natural gases, and the phase equilibria and volumetric properties of acid gas - hydrocarbon mixtures. The application to gas production and processing is illustrated by the phase equilibria involving methanol (a common solvent or hydrate inhibitor) and the solubility at high pressure of gases in polymer materials. In

hydrocarbon processing, the solubility of hydrogen sulfide in hydrocarbons at high temperature is discussed.

For full publication, see attached file.

3-Molecular dynamics simulation of humic substances

Mario Orsi

Abstract

Humic substances (HS) are complex mixtures of natural organic material which are found almost everywhere in the environment, and particularly in soils, sediments, and natural water. HS play key roles in many processes of paramount importance, such as plant growth, carbon storage, and the fate of contaminants in the environment. While most of the research on HS has been traditionally carried out by conventional experimental approaches, over the past 20 years complementary investigations have emerged from the application of computer modeling and simulation techniques. This paper reviews the literature regarding computational studies of HS, with a specific focus on molecular dynamics simulations. Significant achievements, outstanding issues, and future prospects are summarized

and discussed.

Keywords: Humic substances; Natural organic matter; Soil organic matter; Molecular dynamics; Molecular modeling; Molecular simulation.

To view the full paper, please see attached file.

Hoping this will be helpful,

Rafik

That's a rather general question and I'm not completely clear about what you had in mind by 'sea industries'.

Perhaps the obvious answer is ion removal. MD simulations are used to study various ways of separating salt from water: 1) aiming to make it drinkable, 2) selectively removing for example radioactive waste material from seawater.  

I can think of some other MD simulations that are potentially interesting for seawater industries: for example simulating oil at the salt water-air interface. Would form a monolayer I'm guessing. However, I'm making this up as I go, so some literature research would be needed to see what the open questions and applications would be.

Thank you so much for your advice and your precious time. My question is specially about MD application in navy. 

I am extremely grateful for your answers, actually i am masters student of petroleum engineering and i am working on molecular simulation of methane hydrates....... i have faced so many oppositions. Many people think that it doesn't relate to oil and gas , but its so sad that after so many articles i saw relating these two, people still disagree.