Reservoir engineers usually model nonuniformity of permeability within the sandy part of a continuous reservoir to predict reservoir performance. This model will be inadequate whenever the spatial arrangement of the shales, sandy shales and sands within the reservoir is more important to fluid movement. This paper presents the conclusions from three years of outcrop study to determine the permeability variation in sandstones.
An approach for describing the spatial arrangements of sands and shaly sands in a reservoir and to take this arrangement into account in reservoir performance projections is proposed. An empirical heterogeneity factor relationship has been developed.
Généralement, les ingénieurs de réservoir établissent la nonuniformité de perméabilité dans la partie sablonneuse d'un réservoir continu afin de pouvoir prédire le comportement d'un réservoir. Ce modèle, de nonuniformité, sera disproportionné lorsque la disposition des espacements des argiles schisteuses, des argiles sablonneuses et des sables dans le réservoir, est essentielle au mouvement du fluide.
Ce rapport-ci présente les conclusions de trois ans d'études des affleurements pour arriver à déterminer la variation de perméabilité dans les grès. Nous proposons ici une évaluation approximée pour décrire les dispositions d'espacement des sables, et des argiles sablonneuses, dans un réservoir; et, il faut tenir compte de cette condition lorsqu'on fait des projections de comportement dans un réservoir.
On a donc développé ce que nous appelons un facteur empirique d'hétérogénéité qui est, pour ainsi dire, relatif.
The Atlantic Richfield Company undertook the study of sandstone heterogeneities by sampling and analyzing surface outcrops of reservoir type rock. The initial study objective was prediction of the permeability variation and its geometry from normally available data so that flood performances could be more accurately predicted. This was essentially accomplished, but during the study it became obvious that in many reservoirs it was the arrangement of sand and shaly sand rather than the permeability variation within the sand that controls the macroscopic fluid movement. The variety of sandshaly sand arrangements is virtually infinite. However, from the hundreds of outcrops of continuous sandy deposits investigated four basic patterns were recognized as recurring. During subsequent reservoir by THEO. L. POLASEK and C. A. HUTCHINSON, Jr., Atlantic Richfield Company, U.S.A. engineering work these same patterns were repeatedly recognized, and it became increasingly obvious that a more quantitative manner of describing the sand-shaly sand arrangement than just recognition of the dominance of a particular pattern is needed. A technique has been developed for determining a heterogeneity facto
