Abstract: Waste zone in Ukrainian Carpathian autochthone: a new turn in a subthrust play
POPADYUK, IGOR, V
Well Petrovec-3 drilled on a valid subthrust structure farther to the east from well-known Lopushnya field shows water during the testing of Cenomanian sandstones and Late Jurassic back-reef carbonates. This kick caused a reconsideration of a geological model of Ukrainian subthrust.
A new model shows that productivity of Cenomanian-Jurassic reservoir is controlled by the thickness of Turonian-Senonian sequence. These strata consist mainly of marls and chalks that are neither a good reservoir rocks nor a good seal,referred to as a waste zone. If the thickness of waste zone exceeds the amplitude of structure on the top of Cenomanian, such a high will be nonproductive because the effective seal of Sambor nappe, resting above the thick Senonian, cannot cover a reservoir.
So, this three-layered model includes, in ascending order: 1) reservoir rocks (Upper Jurassic-Cenomanian), 2) Waste zone (Turonian-Senonian), 3) real seal (allochthone and/or autochthone Miocene evaporites). It gives an excellent explanation of productivity/non-productivity of Mesozoic sequences in Ukrainian subthrust and adjacent foreland. Some new unconventional views. on Carpathian subthrust are also discussed.
AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria