Abstract: Hydrocarbon inclusions in minerals of the sediments in the Ukrainian and Slovakian Carpathians sediments as possible indicator of oil - gas productivity

DUDOK, IVAN V., OLEG I. PETRICHENKO, ANDREY V. POBEREGSKY, and STANISLAV KAROLI,

Chemical and aggregate composition of hydrocarbons, their thermobaric condition and the time of migration have been determined on the base of fluid inclusion study of epigenetic and diagenetic minerals. Fluid inclusions of epigenetic minerals have been studied from veins hosted in the Jurrasic, Cretaceous and Paleogene sediments occurring in the eastern part of the Slovakian and western part of the Ukrainian Carpathians.

Nascent temperature of minerals varied from 250 - 230 degrees C to 80 - 50 degrees C, the pressure reached 2.7 kbar. The gaseous phase of hydrocarbons is characterized by predominance of methane (in calcite 40 - 80%, in quartz 80 - 100%) with insignificant contents of higher hydrocarbons.

Hydrocarbon composition and fluid pressures regularly change from the Inner Carpathians to the Outer Carpathians geological units. While fluid inclusions in minerals of internal units mostly consist of methane, for external units increasing quantity of fluid inclusions with higher hydrocarbons and solid bitumens is symptomatic. The pressure changed from 1.3 to 2.7 kbar.

Hydrocarbon inclusions in evaporites have been found in the Neogene (Miocene) sediments. These inclusions are solely connected with diagenetic minerals (halite, gypsum) precipitating at temperatures about 70 degrees - 80 degrees C and at pressures lower than 0.03 kbar. Higher hydrocarbons dominate in these inclusions and their presence in evaporites is due to hydrocarbon migration from former, terrigenous sediments. The interpretation of the inclusions data for hydrocarbons prospection is complicated by unclear autochthony of hydrocarbons.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria