This paper is about the changes in the characteristics On illustre les changements des caractéristiques des of petroleum reservoir rocks, caused by fluid pressure roches réservoir qui s'ensuivent à la diminution de la decline. pression dans les gisements d'hydrocarbures.
In particular we will examine the case of
loose On analyse en particulier le cas des roches élastiques sands or of
weakly cemented sandstones with mainly pas cimentées ou faiblement liées avec des ciments calcareous or clayey cements; we will show how in such pour la plupart calcaires ou argileux. On démontre a case
permanent deformations occur in the main. qu'en ce dernier cas les déformations permanentes sont We shall report finally the results of tests carried out prépondérantes. on
sands taken from gas fields in the Po Valley and On rapporte enfin les résultats des épreuves accomshall show the influence exerted by initial composition plies sur les sables que l'on a tirées des gisements de and systems of stresses on the
changes in porosity gaz dans la Vallée du Po en faisant apparaître l'influence and permeability. de la composition et des conditions initiales sur les The report ends by showing the possible applications variations de porosité et de perméabilité. of the experimental results to the study
of pressure Cette note se conclut tout en indiquant les applicadistribution and of thickness changes in petroleum tions possibles de ces résultats expérimentaux à l'étude reservoirs and aquifers. de la distribution de la pression et des variations d'épaisseur dans les strates minéralisées.
At the same time other a ~thor ~ ~ * ~ * ~ ~ ~, ~, ~, ~ ~ ~ ~ ~ have considered in addition to the changes in porosity During the production of an oil or gas field, a the variation of absolute and relative permeability, decrease in the fluid pressure brings about a change in and of the resistivity of the reservoir rock during the characteristics of the reservoir rock. production.
This phenomenon has beellknown for many A theoretical outline of this phenomenon, in the but it was thought to have only a trifling influence on case ofelastic porous media has been given by Bioti3, the production behaviour. Geertsma14, Van der Knaap15, Gassmann16, etc.; The development of the knowledge of reservoir however, one should bear in mind that similar probengineering and of the techniques of measurement of lems had already been met in the field of soil the properties of fluids has called for a greater pre- mechanics17. cision in the determination of rock characteristics.
An interesting critical review of the researches Hall was the first to show the influence ofthe changes of such charactenstics during production in the case carried out in the petroleum field, enriched by original of an undersaturated oil ~ 0 0 1 3.
He det
