Flow of tarry and paraffin-rich oils in porous reservoirs does not follow the Darcy law. For a number of oils and porous media one can use filtration law with an initial pressure gradient. This is revealed by rheological and filtration laboratory experiments, and also by data of well tests in a number of oil fields.
The presence of an initial pressure gradient changes sharply the flow pattern giving rise to stagnant zones in homogeneous fluid flow and to dead areas of motionless oil during water flooding. Calculations show that when the real values of initial pressure gradient are equal to some hundredths of atm/m the stagnant zones and dead areas may occupy a considerable part of the reservoir. Disregard of the peculiarities of flow with initial pressure gradient results in a considerable decrease of oil recovery. This is corroborated by the analysis of development of a great many oil fields in Azerbaijan containing viscous and visco-plastic oils. Recommendations for choice of well patterns and development regimes are given. The peculiarities of exploitation of wells producing viscoplastic oils are also analysed.
Similar non-linear effects occur in gas flow through water-saturated argillaceous rocks. This is revealed in laboratory experiments, as well as the analysis of field data. The existence of an initial pressure gradient in gas flow may reduce the completeness of gas recovery. by A. KH. MIRZADJANZADE, Azerbaijan Institute of Oil and Chemistry, Lenin Av. 20, Baku, U.S.S.R.; A. D. AMIROV, ScientiJc and Technical Society oj Oil and Gas Industry, U.S.S.R.; Z. M. AKHMEDOV, Azerbaijan Institute of Oil and Chemistry, U.S.S.R.; G. I. BARENBLATT, Institute of Mechanics, Moscow State University, U.S.S.R.; R. S. GURBANOV, Azerbaijan Institute of Oil and Chemistry, U.S.S.R.; V. M. ENTOV, Institute of Mechanics, Moscow State University, U.S.S.R.; YU. V. ZAITSEV, Ministry of Oil Industry, U.S.S.R.
L'écoulement des pétroles résineux et paraffinés dans les collecteurs poreux n'est pas descriptible par la loi de Darcy. Pour plusieurs pétroles et milieux poreux on péut appliquer la loi de la filtration au gradient initial. Ce phénomène est mis en évidence grâce à des expériences rhéologiques et de filtration en laboratoire, ainsi que par les données, résultant de l'étude des puits de quelque gisement. La présence du gradient initial modifie essentiellement l'aspect du courant, engendrant des zones de stagnation dans le champ d'écoulement du liquide homogène et des fractions perdues d'huile dans le pétrole en stagnation, lors de l'inondation des puits. Les calculs montrent que dans les cas où le gradient initial atteint la valeur réelle de quelque centièmes d'atm/m, les zones de stagnation et les fractions perdues d'huile peuvent constituter une partie importante de la couche.
