Sedimentological study of the Szőreg-1 reservoir (Algyő field, Hungary): a combination of traditional and 3D sedimentological approaches

Abstract

The paper presents a 3D sedimentological characterization of a delta plain reservoir. The analysis started with detailed core description studies focusing on the genetic interpretations of the sedimentary structures and multivariate statistical analyses, (including Q-mode cluster and R-mode factor analysis), of the sporadic grain-size distributions. These results made the depositional processes of channels, bar-crests and crevasse splays probable. By calibration of the well log responses to the cores with total core recovery, we were able to identify two types of vertical facies transitions: (1) mouth-bars and channels; (2) crevasse splays, crevasse channels and minor mouth bars. In addition, a vertical sequence of a relative thick distributary mouth bar was also recognized. Lateral extension was determined by contouring the sand content on surfaces parallel to the upper time horizon. On these surfaces, the sand content and porosity grid systems facilitated the use of an unconventional 3D geo-cellular modelling approach for both well-log-porosities and sand contents. Since vertical depositional facies were extended into the 3D, rock bodies of the most characteristic channel and mouth bar environments could be cut out from the porosity and sand content models. In this way not only their general geometry and internal characteristics, but also the basic geostatistical features (ratio of anisotropy, the direction of major and minor continuity) of their sand content and porosity were identified.