INTEGRACJA MIKROTERMOMETRII INKLUZJI FLUIDALNYCH I MODELOWAŃ HISTORII TERMICZNEJ/POGRĄŻANIA W BADANIACH POCHODZENIA WĘGLOWODORÓW I ICH NAGROMADZEŃ W SKAŁACH DOLOMITU GŁÓWNEGO (Ca2) PÓŁNOCNO-ZACHODNIEJ POLSKI (OTWÓR WIERTNICZY BENICE-3)

Abstract

FLUID INCLUSION MICROTHERMOMETRY AND BURIAL/THERMAL HISTORY MODELING COMBINED TO REVEAL HYDROCARBON ORIGIN AND ACCUMULATION IN THE MAIN DOLOMITE (Ca2) ROCKS OF NORTHWESTERN POLAND (WELL BENICE-3)

Abstract. Fluid inclusion studies can be very helpful in understanding petroleum genesis and hence aid hydrocarbon exploration. When combined with basin modeling, such studies may allow detailed refinements to the general burial–temperature–pressure history of a sedimentary basin. As a case study, borehole data derived from the Main Dolomite (Ca2) carbonates of the Benice-3 well located within the Kamień Pomorski carbonate platform (KPCP, West Pomerania) of the northwestern part of the Polish Zechstein Basin were considered. The KPCP area contains one of the largest Polish oilfields, Kamieñ Pomorski, localized within the Ca2 platform facies and contains geological reserves of 317974 BBL of oil. The reservoir rocks of the Ca2 are characterized primarily by oolitic dolograinstone facies deposited within the oolite shoal zone. In this study, fluid inclusion data were obtained from early diagenetic anhydrite cements. After pressure correction, these data revealed temperatures within the range 94–110°C with pressures of 270–330 bars. The composition of the brine was found to be from 1.6 to 5.2 wt.% NaCl with small amounts of CO₂ and CaCl₂. This represents formation brines associated with an anhydritization process of the Main Dolomite rocks during shallow-to- intermediate burial conditionss. By integration of the results of fluid inclusion microthermometry with a basin modeling approach claimed that temperatures of 94–110°C were obtained by anhydrite cements during Early–Late Jurassic time. Migration of hydrocarbon-bearing solutions was before migration of fluids which led to anhydritization but after dolomitization.