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Petrophysics is the study if the physical properties of the rocks. The main goal of our petrophysical studies is assessment of the controlling parameters, such as porosity, pore structures, pressure, saturation and mineralogy on sonic velocity and permeability in carbonates. Understanding the relative importance of all these parameters is important to assess the uncertainties that arise when using theoretical equations to interpret or predict velocity, porosity and permeability trends from subsurface data sets.

Our current focus is to test several assumptions in rock physics. For example, experiments have revealed that the basic assumption in Gassmann’s equation, which says that the dry and wet shear moduli are constant, needs to be questioned in carbonates. A series of projects address the causes for this shear modulus variability and the effect of saturation on sonic velocity in carbonates. The results of these experiments will provide a guidance of assessing uncertainties in AVO analysis and time-lapse seismic surveys.

In earlier studies we documented the importance of pore structures on velocity at a given porosity, and qualitatively related pore types to these velocity variations. Digital image analysis of pore structures yield a quantitative way to estimate their influence on sonic velocity and permeability. In addition, high-resolution CT–scans of plug samples increases our pore structure analysis from 2-D to 3-D. Over the last years we started to assemble a data-base on dolomites and plan to focus on the sonic velocity and permeability in dolomites to get a better understanding of the petrophysical behavior of various types of dolomite.

Core material from several drill sites are used for integrated studies of the sedimentologic, diagenetic, petrophysical characteristics of oolithic grainstone bodies which determine the influence of early cementation on sonic and hydraulic properties, and the cause for the heterogeneity in such oolithic grainstone settings.



Current Projects

Petrophysical Calibration of the Coarse-Grained Carbonate Drift Fan, Maldives (Year 2)


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File Size:683KB


Investigators: Emma Giddens, Gregor P. Eberli, Luuk Kleipool, Ralf J. Weger, Christian Betzler, Thomas Lüdmann, and Angela Slagle

Project Objectives:

  • Comprehensively describe the carbonate drift fan in the Kardiva Channel that includes the sedimentologic characteristics, petrophysical properties, and the seismic signature.

  • To reach these goals we will perform the following tasks:

    - Laboratory measurements of porosity, permeability, velocity, and resistivity and relate these properties to the facies, diagenesis, and pore structure of each plug.

    - Measure pore geometries through thin section and SEM analysis.

    - Correlate lithology to logs and seismic data for a thorough calibration of the seismic and log facies of the drift fan.



Testing the Extended Biot Theory in Carbonates of the Maldives


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File Size:565KB


Investigators: Ralf J. Weger, Emma Giddens, Gregor P. Eberli, Christian Betzler, Thomas Lüdmann, and Angela Slagle

Project Objectives:


  • Test the Extended Biot Theory on core and logs from IODP Site U1467 by:

    - Calculating the pore shape parameter k from laboratory measurements of porosity and p-wave and shear wave velocity.

    - Assessing the pore structure with digital image analysis and relating it to the theoretical pore shape parameter k.

    - Correlating Υk to permeability.



Petrophysical Properties of a fringing reef Margin: Pleistocene Dominican Republic


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File Size:704KB


Investigators: Robert Goodin, James S. Klaus, Donald F. McNeill, Ralf J. Weger, and Gregor P. Eberli

Project Objectives:


  • Determine the petrophysical properties (electrical resistivity, ultrasonic velocity, porosity, permeability, and density) of Pleistocene reefal carbonates within DRDP drilling phase II (cores 1, 6, 4, and 5) to expand the petrophysical survey by Ditya (2012) into previously unsampled slope and lowstand reef facies.
  • Assess the relative influence of primary depositional facies and subsequent diagenetic alteration as determined by Diaz (2017) on the measured mechanical and petrophysical properties.



Rock Physics Observations During Controlled Microbially Induced Precipitation


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File Size:330KB


Investigators: Ralf J. Weger, Mara R. Diaz, Peter K. Swart, and Gregor P. Eberli

Project Objectives:

  • To elucidate the involvement of microbes in ooid cementation processes and their potential effect on the acoustic properties of un-cemented ooid sandstone at low pressures.
  • Compare the influence of microbially mediated versus inorganic precipitated cements on acoustic velocity and rock strengths of carbonates.





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