Experimental and modeling study of kinetics for methane hydrate formation in a crude oil-in-water emulsion

Shranish Kar,Sukumar Laik,Ajay Mandal,Himangshu Kakati

doi:10.1007/s12182-016-0108-3

Shranish Kar, Sukumar Laik + Show 2 more

Open Access

https://doi.org/10.1007/s12182-016-0108-3

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Journal: Petroleum Science	Publication Date: Jul 12, 2016
Citations: 21	License type: CC BY 4.0

Affiliation: Indian Institute of Technology Dhanbad

Abstract

A low-viscosity emulsion of crude oil in water can be believed to be the bulk of a flow regime in a pipeline. To differentiate which crude oil would and which would not counter the blockage of flow due to gas hydrate formation in flow channels, varying amount of crude oil in water emulsion without any other extraneous additives has undergone methane gas hydrate formation in an autoclave cell. Crude oil was able to thermodynamically inhibit the gas hydrate formation as observed from its hydrate stability zone. The normalized rate of hydrate formation in the emulsion has been calculated from an illustrative chemical affinity model, which showed a decrease in the methane consumption (decreased normalized rate constant) with an increase in the oil content in the emulsion. Fourier transform infrared spectroscopy (FTIR) of the emulsion and characteristic properties of the crude oil have been used to find the chemical component that could be pivotal in self-inhibitory characteristic of the crude oil collected from Ankleshwar, India, against a situation of clogged flow due to formation of gas hydrate and establish flow assurance.

Highlights

Way back in the 1930s, natural gas hydrates were discovered in gas transmission lines, frequently at temperatures above the ice point
The normalized rate of hydrate formation in the emulsion has been calculated from an illustrative chemical affinity model, which showed a decrease in the methane consumption with an increase in the oil content in the emulsion
Crude oil thermodynamically inhibits the formation of methane gas hydrate as observed in our previous work by Kakati et al (2014)

Summary

Introduction

Way back in the 1930s, natural gas hydrates were discovered in gas transmission lines, frequently at temperatures above the ice point. Emulsions can be encountered in almost all phases of oil and gas production, inside the reservoirs, well bores, and well heads and in transportation through pipelines. Irrespective of the amount of water in the emulsified system, hydrates could form in the emulsion at particular pressure and temperature conditions, which leads to plugging of pipelines due to agglomeration of the hydrate particles into a large mass (Greaves et al 2008; Mu et al 2014). There is a higher rate of hydrate formation as small droplets increase the surface area of contact between gas and water. In the oil-in-water (O/W) emulsion, the large surface contact between water and gas allows maximum mass transfer which increases the gas consumption rate (Douglas et al 2009; Xiang et al 2013). In the oil-in-water (O/W) emulsion, the large surface contact between water and gas allows maximum mass transfer which increases the gas consumption rate (Douglas et al 2009; Xiang et al 2013). Talatori and Barth (2011) found that the nucleation time for methane gas hydrate formation depended inversely on the driving force, i.e., subcooling at a constant water cut and expectedly, the nucleation time decreased when the water cut increased at a constant temperature

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