Poster Session - IFP Invited Poster

Study of agglomeration between gas hydrate particles from water in oil emulsions

E. Colombel (1), T. Palermo (1), L.Barré (1), F. Gruy (2)

(1) Division chimie et physico chimie appliquée, Institut Français du Pétrole, Rueil-Malmaison, France

(2) Laboratoire SPIN, École Nationale Supérieure des Mines de Saint Etienne, France

This work deals with the problem of pipeline blockage by gas hydrates during oil production. Gas hydrates are crystals resulting from water and gas molecules association under high pressure and low temperature conditions. Such thermodynamical conditions are generally encountered in heavy oil production, particularly for deep offshore fields or cold areas. Due to agglomeration process, hydrate occurrence leads to plug formation.

The main objective of this study is to improve our understanding in the mechanisms involved in the agglomeration process, particularly for water in oil emulsions. Results will allow us to supply a theoretical model of agglomeration. This model will be used in the interpretation of tests carried out in flow loops under real conditions.

A model system of Freon hydrates dispersed in xylene with asphaltenes as surfactant is used. As Freon hydrates occur under atmospheric pressure at low temperature, it allows us to apply different techniques without being limited by pressure conditions.

The Nuclear Magnetic Resonance (NMR) technique is mainly used. It makes the measurement of the ratio between solid fluorine in hydrate and total fluorine in the sample possible -enabling to know the quantity of formed hydrates. First experiments were realized with Latex particles to optimize parameters with a well known system. To complete this work, optical microscopy with cooling cell is used to get direct observations of agglomeration. The study is focused on the characterisation of aggregates in terms of size, number of particles and fractal dimension.

Additional techniques are also used. The Differential Scanning Calorimetry (DSC) is used to qualify the agglomeration tendency of these systems. The rheometry technique enables us to study the evolution of the apparent viscosity of the system during hydrate formation and plugging. These techniques can also be applied to study real systems like methane hydrates in crude oils under field conditions.

Key Words: hydrates, freon, emulsion, crystallisation, agglomeration, NMR