Quantitative analysis of facies in a complex depositional environment is have some difficulty in terms of ability to constrain the data available into easily recognizable and reproducible facies types. One of the most challenging environments is the shallow water carbonate depositional system. Using subsurface data, a facies class of Tertiary carbonates of Banggai Basin was established to allow reproducible facies descriptions by multiple workers. The analysis based on core data from Research area (about 2,000 feet of core from five wells)
Tertiary subsurface carbonates of the Research area, range in age from Late Miocene to Early Pliocene and are comprised of diachronously deposited shallow water platform carbonate build-ups and associated with detrital carbonate sediments.
Time equivalent carbonates of the Mentawa member Limestone, showing the same range of environments. On the basis of faunal content, grain types, sedimentary texture, and sedimentary structure, Autochthonous facies types represent reef margin, platform interior, and slope environments ranging from shallow-water, reefal boundstone and rudstone to planktonic foraminifera wackestone and packstone. Allochthonous facies represent grain-dominated, detrital facies types, intercalated within mud-dominated to graindominated facies types; rich in planktonic foraminifera.
Age diagnostic, large benthic foraminifera (LBF), planktonic foraminifera, and calcareous nannoplankton enable the correlation of subsurface data and allow high-resolution sequence stratigraphic correlation throughout the research area. Integration of subsurface data leads to more insightful and realistic geological models of subsurface stratigraphy. The sequence stratigraphic development of the subsurface Paleogene in Research area, Central Sulawesi, was define using well cuttings, core data and wireline logs tied into largely published biostratigraphic and available seismic data.
Large benthic foraminifera assembladges used for detailing depositional environment also associated with reef connected environment. Diagenetic process indicating creation and destruction of carbonate porosity, due to presence of marine, fresh water, pressure and temperature that present in term of tectonic and subsidence. Some of the micritization, recrystallization, and neomorphism .