Page 92 - Basic Well Log Analysis for Geologist

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POROSITY LOGS

Figure 29. Chart for converting bulk density (p)) to porosity (¢) using values picked from a density log.
Courtesy, Schlumberger Well Services.
Copyright 1977, Schlumberger.
Given:
Pima = 2.87 gm/cc (dolomite; Table 7)
Pp; = 1.1 gm/cc (suggested constant fluid density for salt mud: see text)
Py = 2.56 gm/cc at a depth of 9,310 ft (from log; Fig. 28)

Procedure:
1. Find a value for bulk density (p,) on the horizontal scale at the bottom of Figure 29 (in this example 2.56
gm/ec).
2. Follow the value vertically until it intersects the diagonal line representing the matrix density (py) used (in this
case 2.87 for dolomite).
3. From that point, follow the horizontal line to the left where the porosity () value is represented on the porosity
scale at a fluid density (p,) of 1.1. In this case, the porosity () is 18%.

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