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New Unconventional Potential of the Mature Petroleum Provinces in Poland

Abstract

Vast impact of new unconventional hydrocarbons on oil/gas production from mature petroleum provinces was demonstrated during last decades in USA and Canada. The models of unconventional petroleum systems, developed there, are now applied to numerous basins across the World, including Poland. Petroleum provinces in Poland are characterized by mature exploration and production decline, although new unconventional exploration concepts applied here revealed a new significant upscale potential. In the Lower Paleozoic Basin shale oil/gas was explored with some 70 new wells. Obtained gas flow rates are relatively low (14.000 m3/d), although modified fracturing design are expected to increase it. Present analysis indicate, that the basin's recoverable resources could be estimated for several Bcm of shale gas and some 1 BB of shale oil. In the Variscan Upper Silesian Basin a favourable conditions for development of the basin-centered gas system are identified, however so far there is no wells deep enough to verify the play concept. Gas is thought to be sourced from Carboniferous coal source rock buried down to some 4000 m, and is potentially trapped in tight sandstone by permeability jail seal mechanism. Recoverable tight gas resources are estimated in this case for 100-250 Bcm. The Rotliegend (Upper Permian) tight gas is associated mainly with the reservoir eolian facies in the deep part of the Polish Basin. Results of several new wells encourage further exploration with the maximum initial production from vertical well with single frac job equal to 180.000 m3/d. According to Polish Geological Institute recoverable tight gas resources of the Rotliegend amounts to 153-200 Bcm. The key challenge in development of the Rotliegend tight gas fields is high brine production. The Outer Carpathians are producing oil and gas since the mid XIX century. The first recent attempts to stimulated oil/gas production from both shale and tight sandstone by hydraulic fracturing the were successful. In the Miocene Carpathian Foredeep tight biogenic gas is currently produced from the thick pile of mudstone reservoir. New unconventional potential is estimated in this basin for some 150 Bcm of recoverable gas. Significant amount of hydrocarbons might still be trapped in the mature petroleum provinces in Poland, which several years ago were out of any consideration. Their resources remains yet uncertain and requires further testing. Financed by the NCBR, Blue Gas (BG1/LUPZAS/13).