--> --> Abstract: Sonic Velocity in Carbonates--A Product of Original Composition and Post-Depositional Porosity Evolution, by F. S. Anselmetti and G. P. Eberli; #91012 (1992).
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ABSTRACT: Sonic Previous HitVelocityNext Hit in Carbonates--A Product of Original Composition and Post-Depositional Porosity Evolution

ANSELMETTI, FLAVIO S., and GREGOR P. EBERLI, University of Miami, Miami, FL

Results from physical properties analyses on discrete samples from Upper Pliocene to recent carbonates of two core borings in the Great Bahama Bank indicate that sonic Previous HitvelocityNext Hit of carbonates is controlled by two factors: (1) the original composition and (2) the porosity evolution during diagenesis.

In order to understand the relationship between lithology and sonic Previous HitvelocityNext Hit in carbonates, ultrasonic p- and s-wave velocities were measured on discrete samples under varying confining pressure and constant pore pressure. The measured velocities display a wide range between 2.5 and 6.4 km/s. This range is the result of variations in porosity, texture, and original composition of the rock. In general, porosity is inversely correlated to Previous HitvelocityNext Hit and is the primary control on the Previous HitvelocityNext Hit. Deviations from the expected porosity-Previous HitvelocityNext Hit relation, however, are dependent upon the porosity type. Rocks with the same porosity can produce variable velocities: Carbonates with moldic porosity are able to keep a high Previous HitvelocityNext Hit despite high porosity, whereas carbonates with interparticle porosity ave lower velocities at comparable porosity values.

Carbonate-mineralogy has only a minor effect on the Previous HitvelocityNext Hit, but post-depositional diagenetic processes that change mineralogy can alter texture and porosity dramatically and consequently also the Previous HitvelocityNext Hit. For example, fabric destructive dolomitization leads to a decrease in Previous HitvelocityNext Hit, while dolomitic cementation produces an increase.

These analyses show that original composition and processes of diagenesis, especially the post-depositional porosity evolution, determine sonic Previous HitvelocityTop and as a result acoustic impedance in carbonates.


AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)