Ë la suite des travaux de PŽneloux et al. (1982), plusieurs auteurs (Soreide, 1989 ;Magoulas et Tassios, 1990 ;Coniglio, 1993) Ë l'exception de la rŽgion pŽri-critique, la prŽcision reste bonne ˆ basse pression. La nouvelle mŽthode de translation de volume permet de supprimer les incohŽrences des mŽthodes existantes et, ˆ l'opposŽ de cellesci, s'av•re cohŽrente avec les r•gles de mŽlange quand l'on regroupe plusieurs constituants en un pseudo-constituant. Son application aux mŽlanges pŽtroliers appara"t donc prometteuse. (Soreide, 1989;Magoulas and Tassios, 1990;Coniglio, 1993). The present work aims at improving these predictions, particularly in the case of oil and gas reservoirs (temperature up to 200¡C and pressures as high as 120 MPa), using the Peng-Robinson equation of state. As volume translation methods sometimes show inconsistencies at high pressure (e.g., negative thermal expansion coefficient) we had to develop an original expression. For this purpose, we used high pressure density measurements instead of saturated liquid densities. Several pure hydrocarbons from various families were considered: C 6 to C 40 n-alkanes, cyclohexane, C 6 to C 12 monoaromatics.Within a good approximation, the volume translation c is thus shown to follow a linear dependancy with temperature and with molecular weight:where c is in cm 3 /mol, T in K and MW in g/mol.When this expression is used, average errors at high pressure are low (less than 3% for the C 6 to C 13 hydrocarbons investigated With the exception of the near-critical region, the method is still accurate at low pressure. The method does not display the inconsistencies of previous methods, and it is also shown to be consistent with mixing rules when several pure components are lumped into a single pseudo-component. As a consequence, its application to real fluids looks promising. PREDICCION DE LAS PROPIEDADES VOLUMƒTRICAS DE LOS HIDROCARBUROS POR UNA TRANSLACIîN DE VOLUMEN MEJORADAA ra'z de los trabajos de PŽneloux y sus colaboradores (1982), diversos autores (Soreide, 1989 ; Magoulas y Tassios, 1990 y Coniglio, 1993, propusieron mŽtodos de translaci-n de volumen para calcular de mejor modo los pesos espec'ficos de los l'quidos por medio de ecuaciones de estado. El presente trabajo tiene por prop-sito mejorar estas predicciones, y fundamentalmente, en las condiciones reinantes en los yacimientos petroleros (temperaturas hasta 200 ¡C y presiones que alcanzan los 120 MPa), por implementaci-n de la ecuaci-n de estado de Peng-Robinson. Habida cuenta que los mŽtodos existentes son incoherentes en ciertas condiciones (ej. coeficiente de expansi-n tŽrmica negativo) hemos desarrollado una expresi-n original para la translaci-n de volumen. Con este objeto, hemos utilizado las mediciones de peso espec'fico en alta presi-n, y no los pesos espec'ficos del l'quido en saturaci-n. Se han estudiado as' diversos hidrocarburos de distintas familias : n-alcanos de C 6 a C 40 , ciclohexano, y asimismo, monoarom ‡ticos de C 6 a C 12 . La translaci-n de volumen c obedece, aproxi...

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...