Les dŽcouvertes de pŽtrole ou de gaz dans des conditions sŽv•res de tempŽrature (plus de 150¡C) ou de pression (plus de 50 MPa) se comptent dans plusieurs bassins ˆ travers le monde. En mer du Nord, on prŽvoit de mettre en production des gisements dont les conditions de fond vont jusqu'ˆ 110 MPa et 190¡C. Ces caractŽristiques constituent un dŽfi pour la prŽdiction des propriŽtŽs des fluides de gisement, aussi bien au niveau expŽrimental que thŽorique. In order to perform fluid studies for these reservoir conditions, IFP has developed a specific mercury-free high pressure apparatus with sapphire windows, a phase sampling device and viscosity determination by the capillary tube method. Its application is illustrated here using examples of real fluids and model mixtures.This equipment was first used to measure volumetric properties for gases. It has been shown that very high compressibility factors can be found with HP-HT gas condensates. This has a strong influence on recovery factors during primary depletion. In order to predict more accurately the volumetric properties of mixtures under these conditions, we propose to use a conventional equation of state, such as Peng-Robinson, with two improvements:Ð a modified temperature-dependent volume translation method, calibrated for high pressure density data; the method is simple, more accurate than other volume translation methods and fully consistent with lumping procedures; Ð a quadratic mixing rule on the covolume.Specific phase behavior can also be found. At low temperatures, wax crystallization can occur from a fluid which is a gas condensate at reservoir temperature. This feature is due to the simultaneous presence of abundant methane and heavy paraffins. A study of model fluids in a sapphire cell has allowed us to identify the possible types of phase diagrams.Although generally not considered to be an important parameter, gas viscosity may have some importance in the production of HP-HT accumulations, because of high flow rates. Viscosity models exhibit significant uncertainties because of large viscosity contrasts between the individual components of the reservoir fluid. In order to test and improve prediction methods, we started the acquisition of viscosity data under representative conditions. Special care was taken in the implementation of the capillary tube method, so that low viscosities (down to 0.02 mPa×s) could be measured with high accuracy at pressures up to 120 MPa on simple systems, such as methane, n-pentane, nitrogen, and nitrogen-pentane mixtures. As a result, it was possible to evaluate mixing rules for viscosity predictions.
MEDICIîN Y PREDICCIîN DE LAS PROPIEDADES VOLUMƒTRICAS Y DE LAS PROPIEDADES DE TRANSPORTE DE LOS FLUIDOS DE YACIMIENTOS DE ALTA PRESIîNLos descubrimientos de petr-leo o de gas en condiciones severas de temperatura (m ‡s de 150¡C) o de presi-n (mas de 50 MPa) figuran en buen noemero de cuencas en todo el mundo. En el mar del Norte, se proyecta poner en producci-n yacimientos cuyas condiciones de fondo alcanzan los 110 MPa y...
