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In order to produce crude oil three recovery techniques are used: primary, second and tertiary also known as Enhanced Oil Recovery (EOR). Oil production in the Carpatian region is difficult due to the long-term production and significant depletion of reservoir energy. One of the methods that are considered to increase oil recovery factor is CO2-EOR. This method is based on carbon dioxide injection into oil reservoir in order to maintain reservoir pressure and modify physicochemical oil properties. Combination of this method with geological sequestration of carbon dioxide (CCS) relying on its storage in geological structures implemented after the end of production stage brings additional benefits in terms of environmental protection and extends the reservoir life, which translates into a positive economic effect. In this paper an analysis of the possibilities of the CCS-EOR method application on one of the Carpathian oil fields is carried out. Suitable location of injection wells and proper selection of carbon dioxide injection parameters allow a significant increase in the cumulative oil production from the analyzed reservoir what enhances oil recovery factor by 3 percentage points over the 20 years of the forecast. [ABSTRACT FROM AUTHOR]

Wettability as a rock-fluid interaction property is well recognized to affect the multiphase flow in hydrocarbons reservoirs. It impacts on the petrophysical properties of reservoir rock including relative permeability, capillary pressure, electrical properties and enhanced oil recovery. The three most commonly states are differed of wettability for hydrocarbon fields, these include: water wet, oil wet and mixed. USBM and Amott-Harvey laboratory methods are proposed as petroleum industry standards to estimate rock wettability in laboratory conditions. The first technique is directly calculated from area under capillary pressure curves and the second is related to spontaneous and forced characteristics of drainage and imbibition processes. Most oil reservoir rocks are characterized by water-wet since they were formed in marine environments. Generally, carbonate rocks have a moderate to strong oil-wet character of wettability. During oil production reservoir rock can reverse from water-wet towards oil-wet condition because of the solid particles which attract negatively charged chemical compound contained in the migrating hydrocarbon phase. Laboratory measurement of wettability at reservoir conditions is a key factor for the success of EOR application on the oil field. In presented work, the determination of wettability at laboratory environment on standard sandstone and dolomite core plugs by Amott-Harvey test was carried out. These rock samples correspond to the main oil bearing formations which are taken into account as the potential EOR candidates. The obtained results show wettability for sandstone as water-wet and oil-wet for dolomite rock. In this paper determination of wettability is considered as a one of multiple preliminary factors considered as crucial parameter during selecting IOR and EOR method application for the Polish oil fields. For sandstone rocks IOR methods based on water flooding are recommended and EOR methods, especially gas injection are selected for dolomite formations. The proper understanding of the wettability of the reservoir is essential for determining the most efficient way of oil production. [ABSTRACT FROM AUTHOR]