Early Versus Late Dolomitization of the Miocene Luconia Platform: Insights from ‰13C, ‰18O, 87Sr/86Sr and Fluid Inclusions of Isolated Cement Generations
Warrlich, G.1,
C. Taberner2, M. Esteban3, A. Dombrowski1,
J.H. Van Konijnenburg4, M. Rejas2, M. Boya-Ferrero1 (1)
Shell International Exploration and Production B.V, Rijswijk, Netherlands (2)
Institute of Earth Sciences, CSIC, Barcelona, Spain (3) Carbonates
International
Dolomitization of pinnacles from Luconia Miocene carbonate reservoirs
(bottom
hole temperatures and salinities of formation waters. The ‰13C
and ‰18O values of dolomite and late calcite microsamples display a
parallel trend towards lower ‰13C and ‰18O suggesting
similar parental brines, as well as the record of an increase in water:rock
ratios and in the supply of organically-derived CO2. Calculated ‰18O
of parental fluids are similar to formation waters. 87Sr/86Sr
of dolomite and late calcite cements have similar ratios to the original marine
sediments (Early to Middle Miocene) suggesting significant rock buffering.
Integrated
paragenesis, geochemistry and fluid inclusions of isolated dolomite and late
calcite cements support late burial dolomitization and late corrosion by
deep-seated fluids of similar chemistries and temperatures to those recorded in
formation waters. Predicted porosity and permeability patterns are different
when a late dolomitization model is applied to the Luconia carbonate reservoir.
PETRONAS is acknowledged for permission to present these results.