The appearance of sedimentary genetics in the petrophysical and textural characteristics of Szőreg–1 reservoir, South Hungary — A form of geomathematical approach

Abstract

The aim of this study is to examine the effect of the sedimentary genetics of Szőreg–1 reservoir on sedimentary textures
and petrophisical properties, and to summarize their relationships as revealed by geomathematical examination methods.
During the data analysis, the drilling data of wells deepened into the residual gas cap were processed. A detailed genetic
description of core samples and the interpretation of sedimentary facies units were followed by the definition of sedimentary
facies. The information-gathering with respect to the properties of the pore space was also supported by scanning electron
microscopy studies (Mol Plc.). The geostatistical methods used for exploring the data included multivariate statistical
analysis (in this case, factor analysis), tests of cumulative frequency distribution, and also the partial correlation method.
The Szőreg–1 reservoir is a gas-capped oil play within the Algyő Structure, lying in the Upper Pannonian Újfalu
Formation. It is a part of the largest hydrocarbon accumulation of Hungary settled on a delta plain. Accordingly, four
sedimentary facies can easily be distinguished related to the delta sequence: (1) natural levee – distributary channel –
channel abandonment transition, (2) prograding crevasse splay – swamp transition, (3) prograding distributary channel –
crevasse splay – prograding crevasse splay transition and (4) swamp – distributary channel transition. The vertical and
horizontal permeability and porosity data examined in this study were measured on cores as well as carbonate content and
grain-size surveys. (Mol Plc.). The investigations concluded that the pore space of sandy sediments forming the Szőreg–1
reservoir can be regarded as a primary sedimentary pore space; however, the impacts of secondary pore space play a
tributary role, and the reservoir habitat of the rock body can be regarded as a non-negligible factor. The secondary
carbonate minerals in the pore space appear to occur at the level of micropores.