###### Abstract
However, this thesis did not present any original experimental data, it is essentially a compilation of pre-existing data from diverse sources (e.g., [24; 25; 26; 27; 28; 29]), most of which are inaccessible. This thesis, which is available online [23], reports summaries of results, the data compilation being provided only on a CD-ROM, which was unavailable to us; this dataset, held by MOL, remains confidential. Furthermore, this thesis presents aggregated results for the various sandstone facies present, there being no differentiation between the Szolnok Fm. (turbiditic), Ujfalu Fm. (delta), and Zagyva Fm. (fluvial); as Figure 1 indicates, core samples from circa 2 km depth might be from any of these subdivisions. Nonetheless, [PERSON] [23] reported that for reservoir sandstones from \(\sim\)2 km depth the horizontal permeability is typically \(\sim\)50% larger than the vertical permeability, both values being typically in the range \(\sim\)100-200 mD; the porosity of these rocks is typically \(\sim\)0.22 [23]. A major reason for the lack of recent quantitative studies of reservoir properties is that much of the core data was recovered decades ago and the amount of high-quality material that remains in the public domain is relatively limited. Furthermore, coring had low recovery because of the unconsolidated nature of many Pannonian sandstone formations. At the start of this study in 2018, we consulted MBFSZ and MOL Plc. (Magyar Olaj- es Gazipari Reszvenystarsag, Hungarian Oil and Gas Public Limited Company), who maintain in Szolnok a core repository for petroleum wells in the Pannonian Basin. Access to core in the Ujfalu Fm. from wells in the Bekes Basin (Figure 1) was requested. Many core samples were available from the Ujfalu Fm. elsewhere in Hungary and/or from other formations in the Bekes Basin. However, for the Ujfalu Fm. in the Bekes Basin, the few core samples of sandstone that were collected, and were large enough for conventional laboratory experiments (i.e., plugging and flow experiments) to measure porosity and permeability, appear to have been processed long ago, the left-over fragments from wells in this area that were available to us from the MOL core repository being too small to be analyzed in this way. This paper aims to begin filling this data gap on reservoir properties. We explore methods to extract porosity and permeability data from core material that is unsuitable for laboratory flow experiments. We obtained core for the Ujfalu Fm. from the legacy Kond-1 and Gyoma-1 petroleum wells in the Bekes Basin (Figure 1). These fragments are analyzed using thin section analysis, Mercury Intrusion Porosimetry (MIP), X-ray Diffraction (XRD), X-ray Computed Tomography (X-CT) imaging, and numerical flow simulations. The thin section analysis and XRD provide information on mineralogy, for the assessment of scaling and reservoir erosion risks. MIP, X-CT imaging, and numerical flow experiments provide new porosity and permeability data. We then compare the permeability values from these experiments with estimates from production tests from two geothermal wells at Mezobereny, also in the Bekes Basin (Figure 1). These wells were drilled in 2012 to depths of ~2000 m and target the Ujfalu Fm. [15,18]. With this approach we not only provide new data but also highlight the need for more reservoir characterization of Pannonian Sandstones. This is crucial for future efforts to avoid and solve injection problems and optimize exploitation of the enormous geothermal resource in this region. This paper is structured as follows: in section two our dataset is presented and the production tests and associated permeability estimates are discussed. In section three we describe the experimental methods in more detail, with section four presenting our results. The validity and applicability of our work are then discussed.