Diagenesis continuously alters carbonate rocks and consequently their petrophysical properties. Our research projects have thus a double focus; one to understand the diagenetic processes, and two, to relate the diagenetic alterations to the resulting rock properties. 
Modern sediments on Great Bahama Bank and elsewhere provide baseline information about the geochemical signature of “unaltered” carbonate platform sediments. Cores from the shallow subsurface along the western margin of Great Bahama Bank and in Florida document the effects of early diagenesis on porosity, velocity, and permeability in platform carbonates and grainstone shoal complexes in particular. The geochemical studies of the dolomites and limestones from deeper cores on Great Bahama Bank and the Marion Plateau are ideal to examine the influence of burial diagenesis on the petrophysical properties and to assess the fluid flow in isolated carbonate platforms. Deeply buried rocks that were later uplifted such as the Mississippian Madison Formation underwent several episodes of diagenesis from shallow to deep burial. Our current geochemical projects in this formation try to unravel these different episodes and to document the importance of each event on the reservoir quality of the formation. In addition, we test the applicability of geochemical tracers, in particular δ13C for the stratigraphic correlation of the widely spaced section in Wyoming and Idaho and to other sections around the world.

Understanding the factors that sustain good porosity and permeability values in the subsurface is still a problem. Rock mechanics experiments show that even applying pressures in simulation to real burial depth, carbonate rocks can maintain good reservoir quality, and some permeability was maintained even after increasing the compaction until the pores collapsed. Our working hypothesis is that cementation during the early diagenesis is the main factor for sustaining the reservoir quality, porosity and permeability at great depth. To test this hypothesis, we plan compaction experiments of modern sediments and Pleistocene samples with different amounts of cementation to assess the decrease of this initial porosity and permeability at different burial depths. The results will provide much needed information on the factors that maintain porosity and permeability in the deep burial realm.

The results of this project will provide new insights into (i) the correlation between the inorganic and organic carbon fractions measured in the basin sediments, and its subsequent degradation in the middle and upper slope cores, (ii) the utility of using stable carbon isotopes for stratigraphic correlation, and (iii) the use of the difference in the δ13C between organic and inorganic components as indicators of the pCO2 in the atmosphere.

Carbon sequestration is an important aspect of the response of the United States to the problem of anthropogenically induced global warming. The technology of sequestering CO2 into underground reservoirs is known as Carbon Capture and Storage (CCS). However, assessment of the efficiency, safety, and long term fate of CO2 sequestered into various types of geologic reservoirs remains a challenge. In this project we will deploy field instruments capable of measuring the stable isotopic composition of CO2 in order to ascertain leakage from storage sites.

The recognition that clumped isotopes of CO2 are solely dependent upon temperature and not on the isotopic composition of the fluid from which they are formed has opened significant possibilities in unraveling the temperature and water signal as applied to diagenetic carbonates. The purpose of this project will be to investigate this technique as applied to sedimentary carbonates.

This project is designed to investigate the use of the stable isotopes of sulfur (32S and 34S) in carbonate associated sulfate (CAS) as a possible diagenetic tool to understand the paragenesis of certain carbonates in particular dolomites and carbonates formed in high temperature.