--> Abstract: Carbon Dioxide Sequestration in Carbonates: Main Petrophysical and Geochemistry Issues During Flooding Tests of San Andres Formation Cores, by Gloria S. Garcia, Waylon House, and Necip Guven; #90039 (2005)

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Carbon Dioxide Sequestration in Carbonates: Main Petrophysical and Geochemistry Issues During Flooding Tests of San Andres Formation Cores

Gloria S. Garcia1, Waylon House2, and Necip Guven2
1 Kinder Morgan, Snyder, TX
2 Texas Tech University, Lubbock, TX

To assess the potential of storing carbon dioxide in carbonates, cores from the West Texas San Andres formation were subjected to petrophysical and geochemical evaluation. The purpose was to examine potential petrophysical and geochemical alterations as a result of CO2 and natural formation brine interactions. Natural formation brine (70,495 mg/L of total dissolved solid) from Permain Basin reservoirs was used. Static and core flooding tests were performed under supercritical and simulated reservoir conditions (2000 psia and 150¢ªF). The static tests showed that a precipitate was formed from the brine alone after reaction with CO2. The precipitate was analyzed to identify the new minerals using Scanning Transmission Electron Microscopy (STEM), energy-dispersive spectrometry (EDS) and X-ray-diffraction (XRD). Observations indicate that the precipitate formed is primarily calcite, dolomite, gypsum, halite and other sulfate and carbonate salt minerals. The permeability and porosity alterations in the cores were evaluated performing conventional core analysis and Nuclear Magnetic Resonance (NMR) petrophysical analysis. The permeability was reduced by about 50%, and the pore volume and porosity by about 25% after the injection of only a few pore volumes. The total equilibrium magnetization (Mo) from NMR T2 distribution is decreased by about 17%, indicating substantial reduction in porosity and permeability. The small pore sizes (bulk volume irreducible-BVI) increased on average by about 70% and the large pore sizes (free fluid index-FFI) decreased by about 24%. Slight increases in, permeability and porosity occurred after several pore volumes were injected.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005