HYDRATES PROBLEM WITHIN THE FRAMEWORK OF MULTIPHASE PRODUCTION AND TRANSPORT OF CRUDE OILS AND NATURAL GASES .1. PHYSICAL-CHEMISTRY OF HYDRATES FORMATION AND DISSOCIATION

Off shore exploitation of fossil fluid fuels has emphasized the need o f improving our knowledge on hydrates which can plug production, treat ment and transport facilities. In this paper, the molecular structure of I, II and H hydrates is recalled, then the physical-chemistry of th eir formation is briefly reviewed from both the thermodynamic and the kinetic points of view. Finally, the possible remedies to the problems met by operating companies are described, mainly classical thermodyna mic inhibitors such as alcohols or salts which decrease the hydrates f ormation temperature, and dispersant additives which avoid crystals gr owth and/or agglomeration. At last an original circulation loop at pil ot scale is presented, its characteristics which allow the testing of dispersant additives under representative hydrodynamic and physico-che mical conditions being outlined.