Abstract Composition pattern of natural gases with high CO, content and origin of COz was studied. To predict thermodynamic behaviour of natural gases containing a high percentage of COz under extreme reservoir conditions generalised functions were prepared. These are presented in connection with an actual gas field, up to 433°K temperature and up to 32 MPa pressure.
This natural gas contains 80% v COz and 0.5% v H, S and is produced together with hydrocondensate and liquid water. For this reason corrosion control was needed. For that purpose the effect of natural and commercial inhibitors was studied too.
Résumé Des fonctions généralisées ont été élaborées pour la prévision du comportement thermodynamique des gaz naturels à teneur élevée en CO, dans des conditions extrêmes de gisement. L'applicabilité de ces fonctions a été justifiée par les expériences sur un gisement de gaz réel, avec des températures de 250-433"K, et une pression allant jusqu'à 32 MPa. Ce gaz contient 80% v de CO, et 0-50/, v de H, S et il est associé avec du condensat et de l'eau liquide; c'est pourquoi une vigoureuse protection contre la corrosion est indispensable. L'effet des inhibiteurs naturels et commerciaux a été examiné.
1. INTRODUCTION temperatures especially if their inert content is high; conditions which are characteristic of a few of the natural gases with "extreme" composition found in In this paper, production problems of such reservoirs Hungary contain considerable amounts of non- will be discussed comparing the results of theoretical hydrocarbon components. Utilising these in a total energy system the presence of carbon dioxide has a special importance as in the reservoirs discovered till now the economically recoverable reserve has exceeded 1010 scm. It should be mentioned that a crucial proportion of this volume is found in natural gases, in which the concentration of carbon dioxide is above 50 mole % (Fig. i), this being in a few comparatively large reservoirs.
Unfortunately, the physico-chemical properties and reservoir behaviour of carbonated natural gases are not sufficiently known under extreme pressures and Crude oils, gas-condensate systems and mostly fields in Hungary. considerations with field experience.
Fig. 1-Distribution in Hungary of carbon dioxide reserves according to carbon dioxide content of natural by AKOS BAN, gases.
Hungarian Oil and Gas Trust, Hungary, VALER BALINT, Transdanubian Oil and Gas Co., Hungary, SANDOR DOLESCHALL, CARBONATED NATURAL GASES Central Research Institute for Physics of the Hungarian Academy of Science, Hungary, and JANOS TOROK, Oil and Gas Industrial Research Laboratory, Hungary
2. COMPOSITION AND ORIGIN OF Figure 2 shows the average composition pattern of hydrocarbons as a function of carbon di