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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



DETECTING PORE TYPES USING VELOCITY AND RESISTIVITY

Weger_poretypes_CSL2021

Project Media
     
Weger_por...2021.pdf
Media Type:Media Type
File Size:580KB

 

Investigators: Ralf J. Weger and Gregor P. Eberli

Project Objectives:

  • Discriminate connected interparticle from separated moldic porosity using petrophysical properties.
  • Combine resistivity and velocity to discriminate samples with simple pore geometries and connected pores from samples with simple pore geometries and disconnected pores.


     

PETROPHYSICAL CHARACTERISTICS OF CARBONATE DRIFT DEPOSITS

Weger_driftpetrophysics_CSL2021

Project Media
     
Weger_dri...2021.pdf
Media Type:Media Type
File Size:443KB

 

Investigators: Ralf J. Weger, Gregor P. Eberli and Greta Mackenzie

Project Objectives:

  • Prepare a data report of the samples from the delta drift in the Maldives.
  • Complete the analysis of the petrophysical properties of delta drift deposits in the Maiella.
  • Relate log signature of carbonate drift deposits and relate to drift type and mineralogy.
  • Produce a catalogue for discriminating logs of slope and basin deposits from carbonate contourite drifts.

 



     

EARLY MARINE CEMENTATION PROCESSES AND VELOCITY EVOLUTION

Diaz_cementation_CSL2021

Project Media
     
Diaz_ceme...2021.pdf
Media Type:Media Type
File Size:377KB

 

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

Project Objectives:

  • To investigate the role of microbes in ooid lithification processes that leads to the formation of grapestones and rocks.
  • Compare the influence of biologically mediated versus inorganic precipitated cements on acoustic velocity and rock strength of carbonates.



     

DECODING SUBTLE DIAGENETIC ALTERATION: COMBINING GEOCHEMICAL AND PETROPHYSICAL APPROACHES

Oehlert_decodingdiagenetic_CSL2021

Project Media
     
Oehlert_d...2021.pdf
Media Type:Media Type
File Size:713KB

 

Investigators: Amanda M. Oehlert, Peter K. Swart, Ralf J. Weger, and Gregor P. Eberli

Project Objectives:

 

  • Contribute enhanced records of δ13C and δ18O values, as well as major, trace, and ultra-trace elemental concentrations at Unda, Clino, ODP Site 1003, and ODP Site 1006.
  • Assess diagenetic variability (cementation/dissolution, isotopic signatures) in shallow marine carbonates using geochemical, petrophysical, and seismic sequence stratigraphic approaches.

 



     
 

 

 

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