Capillary pressure curves were established on Résumé%. Des courbes de pression capillaire pour des roches reservoir rocks of low permeability originating from oil de réservoirs de foible perméabilité provenant de giseond gas reservoirs in Germany. Such measurements in con- ments allemands de pétrole et de gaz ont été determinées. nection with petrographic studies and the interpretation of Jointes aux études pétrographiques et à l'interprétation des electric logs provide information on pore size distribution diagrammes électriques ces ldéterminotions fournissent des and fluid saturation of the specific rock material. Some informations importantes sur la structure des roches du problems are discussed which arise during the measure- point de vue de la porosité et sur la saturation des pores. ments and application of (mercury) capillary pressure cur- On discute quelques problèmes essentiels dans la déterves, which are particularly important for reservoir rocks of mination et l'emploi des courbes de pression capillaire de low permeability. The possibilities discussed for solution of mercure, spécialement en ce qui concerne les roches de these problems may facilitate the evaluation of low perme- réservoir d'une perméabilité faible et on indique quelques ability reservoirs, even if only drill cuttings are available. possibilités de résoudre ces problèmes qui peuvent être d'utilité dans I'évaluotion de tels gisements, même si on ne dispose que de cuttings ».
Introduction vantage of being less time consuming and allows measurement of a greater range of capillary pres-Natural petroleum reservoir rocks contain voids sures. However, difficulties can be encountered having capillary dimensions. The finer the pores when converting the measuaed capillary pressure of a rock, the more important are the inherent capil- data, obtained by mercury injection, to values lary forces. Therefore capillary pressure data con- which are representative of the behavior using tribute considerably towards evaluating reservoir reservoir fiuids. rocks having low permeabilities. From these curves In the first section of this paper applications are conclusions can be drawn regarding the pore struc- described for use of mercury injection curves to ture, the saturation relationships, and the conditions evaluate pore size distribution and to estimate of flow of the various reservoir fluids. water saturation in little permeable reservoir rocks.
The mercury injection method of W. R. Purcell') Also problems are discussed which were encounterhas proved especially suitable for measuring capjl- ed when the laboratory results were converted into lary pressure curves on core samples having low values representing reservoir conditions. In the permeability. Compared to the restored state techni- second section results of the experiments are que, whi
