Reservoir properties of the Upper Rotliegend and the Weissliegend sandstones (Permian) in the Zielona Góra Basin (western Poland)

Abstract

The Up per Rotliegend/Weissliegend sand stones in the Zielona Góra Ba sin are char ac ter ized by poorer res er voir prop er ties than in the cen tral part of the Pol ish Rotliegend Ba sin. How ever, there have been no de tailed stud ies of the rea sons for these dif fer ences. The main aim of this pa per is to in ter pret the fac tors that played a ma jor role in the dis tri bu tion of res er voir proper ties in the Zielona Góra Ba sin. Anal y sis of vari abil ity in res er voir prop er ties was per formed us ing po ros ity-depth, per meabil ity-depth, and per me abil ity-po ros ity plots. The res er voir qual ity ra tio (RQ), cal cu lated by mul ti ply ing po ros ity and per me abil ity val ues, was also in tro duced. The RQ ra tio was found to be a use ful tool to dis tin guish six types of res er voir rocks. Anal y ses of the vari abil ity of res er voir prop er ties, cou pled with mi cro scopic ob ser va tions, were dis cussed in re la tion to the sed i men tary set ting of each type of rock. These sedimentological and pet ro graph i cal stud ies were in tended to de ter mine the vari abil ity of res er voir prop er ties with re spect to pri mary depositional or lithofacies ef fects and sec ond ary diagenetic effects. The re sults in di cate that ce men ta tion was a ma jor fac tor con trol ling the dis tri bu tion of res er voir prop er ties, mainly by af fect ing the amounts of car bon ate, sul phate, and illite. Com pac tion had only a mi nor in flu ence on the res er voir prop er ties stud ied here.

X-ray micro computed tomography characterization of porosity in Rotliegend sandstones on the northern slope of the Wolsztyn Ridge, western Poland

“…Early car bon ate ce ments may have been formed as a re sult of the in fil tra tion of ma rine wa ters from over ly ing Zechstein carbon ates (e.g., Buniak et al, 1999Buniak et al, , 2009Kiersnowski et al, 2010b;Poszytek, 2014). This may have oc curred in the up permost Rotliegend sand stones, where per me able ae olian sandstones are over lain by Zechstein de pos its; the zone of ce menta tion may be up to tens of metres thick (Poszytek, 2014).…”

“…The flu vial F1 sand stones are sim i lar to the A2 sand stones, de spite their dif fer ent or i gins, and may in fact rep re sent flu vial sands which were re de pos ited by ae olian pro cesses dur ing dry pe ri ods. Sim i larly, some ae olian sands may have been re de pos ited by flu vial trans port dur ing wet pe ri ods (Kiersnowski et al, 2010b;Kiersnowski, 2013;Poszytek, 2014), and some flu vial and ae olian sand stones may there fore have sim i lar lithologies and po ros ity dis tri bu tions. By con trast, F2 sand stones are char ac ter ized by a higher ma trix con tent and poorer grain sort ing and, as a re sult, the po ros ity of these sand stones is very low.…”

“…This may have oc curred in the up permost Rotliegend sand stones, where per me able ae olian sandstones are over lain by Zechstein de pos its; the zone of ce menta tion may be up to tens of metres thick (Poszytek, 2014).…”

“…The Up per Rotliegend section is com posed of al lu vial and flu vial rocks with a con sid er able pro por tion of ae olian sand stones in the cen tral part of the Poznañ Ba sin. Ae olian sand stones are the main res er voir rocks for gas ac cu mu la tion (Jarzyna et al, 2009;Papiernik et al, 2010;Poszytek, 2014). The res er voir prop er ties of ae olian sand stones are char ac ter ized by very good po ros ity (>20%) and per me abil ity (>1000 mD) and form a wide zone in the central part of the ba sin.…”

Sand sheets interaction with aeolian dune, alluvial and marginal playa beds in Late Permian Upper Rotliegend setting (western part of the Poznań Basin, Poland)

“…These de pos its con tain sin gle interbeds of sand sheets. A small part of these sand sheets is ob served in the up per units of the pro files from some of the bore holes within the South ern Erg (Silesian-Zielona Góra Rotliegend Ba sin; Poszytek, 2014).…”