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Petrophysics

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 CHARACTERISTICS OF CARBONATE DRIFT DEPOSITS

Giddens_et_al

Project Media
     
Giddens_e...2020.pdf
Media Type:Media Type
File Size:509KB

 

Investigators: Emma L. Giddens, Gregor P. Eberli and Ralf J. Weger

Project Objectives:

  • Define the specific petrophysical characteristics (porosity, velocity, resistivity and permeability) in plugs and logs of carbonate contourite drifts using data from drifts in the Maldives, Maiella, Australia, and the Bahamas.
  • Contrast the petrophysical properties of drift deposits to those of “other carbonates”, representing various depositional environments, lithology and composition.
  • Investigate the pore structure of fine-grained carbonate drift deposits in search of an explanation for their high resistivity.

 

 



     

CALIBRATING ACOUSTICAL AND ELECTRICAL PROPERTIES TO TOC DISTRIBUTION IN THE VACA MUERTA FORMATION, NEUQUÉN BASIN, ARGENTINA

Weger_et_al

Project Media
     
Weger_et_...2020.pdf
Media Type:Media Type
File Size:221KB

 

Investigators: Ralf J. Weger, Max Tenaglia, Leticia Rodriguez Blanco, Peter K. Swart, and Gregor P. Eberli

Project Objectives:

  • Calibration of acoustical and electrical properties to TOC measurements on plug samples from the Vaca Muerta Formation.
  • Document resistivity anisotropy observed in mixed carbonatesiliciclastic plug samples from the Vaca Muerta Formation.
  • Determine the potential variability of TOC values derived with the ΔlogR method using horizontal v.s. vertical plugs (e.g. logs from vertical v.s.
  • horizontal wells).

 



     
 

 

 

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