--> Abstract: Deriving Pore Structure and Permeability from Sonic Velocity in Carbonates; #90063 (2007)

Datapages, Inc.Print this page

Deriving Pore Structure and Permeability from Sonic Velocity in Carbonates

 

Weger, Ralf J.1, Gregor Eberli2, Gregor Baechle1, Jose Luis Massaferro3, Yueng Fen Sun4, Guido Bracco Gartner5 (1) University of Miami, Miami, FL (2) University of Miami, RSMAS, CSL, Miami, FL (3) Repsol YPF, Madrid, Spain (4) The Petroleum Institute, Abu Dhabi, United Arab Emirates (5) Shell, Rijswijk, Netherlands

 

Two significant questions in carbonate petrophysics are: (1) which objective, quantifiable aspects of pore geometry best explain commonly observed scatter in carbonate velocity-porosity cross-plots; and (2) what is the importance of geometrical characteristics of pore space on acoustic velocity relative to other physical properties? Quantitative descriptions of pore geometry in carbonates and laboratory measurements of acoustic properties are used in this study to develop an empirical link between quantitative digital pore space parameters, acoustic velocity, and permeability. Comparison of petrophysical attributes of carbonate core plugs, geologic description, and quantitative digital parameters describing pore space geometry demonstrate that: (1) geometric information captured by geological descriptions of pore type in carbonates explains some scatter in velocity-porosity cross-plots; (2) four quantitative geometrical parameters that capture pore size, pore surface roughness, aspect-ratio, and pore network complexity statistically capture characteristics that quantitatively differentiate thin sections from each other; (3) two of these parameters (perimeter-over-area and dominant-pore-size) clearly quantify the deviation of acoustic velocity from Wyllie's time average equation; (4) internal rock geometry influences acoustic velocity and permeability most strongly in high porosity carbonate rocks. The findings from this study imply that: (1) estimating porosity from acoustic data can be substantially improved by incorporating information on quantitative pore space geometry; and (2) in cases where good estimates of porosity are available (e.g. from well or seismic data ) quantitative pore geometric characteristics can be estimated directly from acoustic data. These quantitative geometric characteristics of the pore space can be used to estimate permeability from acoustic data.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California