Growth Kinetics and Mechanics of Hydrate Films by Interfacial Rheology

Abstract

A new approach to study and understand the kinetics and mechanical properties of hydrates by interfacial rheology is presented. This is made possible using a "double wall ring" interfacial rheology cell that has been designed to provide the necessary temperature control. Cyclopentane and water are used to form hydrates, and this model system forms these structures at ambient pressures. Different temperature and water/hydrocarbon contact protocols are explored. Of particular interest is the importance of first contacting the hydrocarbon against ice crystals in order to initiate hydrate formation. Indeed, this is found to be the case, even though the hydrates may be created at temperatures above the melting point of ice. Once hydrates completely populate the hydrocarbon/water interface, strain sweeps of the interfacial elastic and viscous moduli are conducted to interrogate the mechanical response and fragility of the hydrate films. The dependence on temperature, Tf, by the kinetics of formation and the mechanical properties is reported, and the cyclopentane hydrate dissociation temperature was found to be between 6 and 7 °C. The formation time (measured from the moment when cyclopentane first contacts ice crystals) as well as the elastic modulus and the yield strain increase as Tf increases.

Bingham’s model in the oil and gas industry

“…Clathrate hydrates are ice-like inclusions that-under appropriate thermodynamic conditions-form at the interface between water and hydrocarbons or low molecular weight gases, by trapping the guest species within cages of hydrogen-bonded water (Sloan and Koh 2008;Leopércio et al 2016).…”

Effect of Cyclopentane Hydrates on the Stability of Dodac and Aot Structures

“…However, for temperatures within the range where C5-cyclic hydrates can be formed -T ≤ 7 o C (Nakajima et al, 2008), the stability of the system increases with increasing temperature. Leopércio et al (2016) verified in strain sweep experiments that, within a temperature range of 1.0 to 7.0 °C, the hydrate film formed at the interface between water and C5cyclic is more structured the higher the temperature. That is, the increase in stability of the D 7.0 system with increasing temperature within the hydrate zone may be related to the formation of stronger hydrate films on the surfaces of the emulsion droplets.…”

Polyhydroxy gemini surfactant as a mechano-responsive rheology modifier for inverted emulsion drilling fluid

“…Interfacial viscoelasticity of paraffin/water interface, paraffin + SPAN-80/water interface and paraffin + SPAN-80/water + PGS interface was evaluated using MCR301 interfacial rheometer (Anton Paar Inc., Austria) at 25 C. 34 A bicone-type rotor was used to nd the paraffin/water interface through the following procedures: rst 100 mL water phase was slowly poured into the cylindrical container; then, the rotor moved vertically until the boundary between two cones was settled accurately at the water surface; nally, 50 mL paraffin phase was poured on water phase carefully. Oscillation frequency was increased from 0.01 Hz to 10 Hz logarithmically, and the corresponding interfacial complex modulus |G*|, elastic modulus G 0 and viscous modulus G 00 were recorded.…”