maa Apparent Matrix Density jisft 130 120 110 100 90 80 70 60 50 40 30
Figure 5-100. Chart for finding apparent matrix density or apparent matrix transit time from bulk density or interval transit time and apparent total porosity [199].
3 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2 Pmaa. Apparent Matrix Density (g/cc)
Figure 5-100. Chart for finding apparent matrix density or apparent matrix transit time from bulk density or interval transit time and apparent total porosity [199].
its propagation velocity is reduced. The wave then refracts to the borehole where it is sequentially detected by the two receivers. How much the wave is attenuated is a function of the dielectric permittivity of the formation. Rocks and oil have similar permittivities while water has a very different permittivity. Therefore, the wave responds to the water-filled porosity in the formation, and the response is a function of formation temperature.
Since the wave is attenuated by water (and is not too bothered by oil), the log response indicates either R^ , (in water-based mud systems) or bulk volume water (in oil-based mud systems'^.
In order to provide usable values, the velocity of the returning wave is measured and compared to the wave-propagation velocity in free space. The propagation velocity of the formation is then converted into propagation time (Tpl). A typical log presentation includes a Tpl, curve (in nanoseconds/meter), an attenuation curve (EATT) in decibels/meter, and a small-arm caliper curve (which measures borehole rugosity) recorded in tracks 2 and 3. Figure 5-104
©Schlumberger
Figure 5-101. Chart for finding porosity and matrix composition from a litho-
©Schlumberger
Pe, Photoelectric Cross Section (barns/electron)
Figure 5-101. Chart for finding porosity and matrix composition from a litho-
density log in fresh water [199].
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