Breakout is often associated with fractures (Crain 1984).

compressional velocities with geological time and depth of burial of the rock, (Faust, 1951). Fluid density (track 1) and spinner survey (tracks 2 and 3). Figure 20.9 can then be used to derive both the total and effective porosities from the density and neutron log readings in the formation of interest. Therefore, their identification and modeling is important for the reservoir characterization and history matching. Vuggy porosity is a type of porosity in carbonate rocks. Find the lowest consistent value of sonic travel time, lowest density, porosity, (or highest density), and lowest neutron porosity in the zone to be interpreted. Manyanalysts use density porosity alone calculated from the bulkdensity with a variable grain matrix to correct for mineral composition (pyrites and clay minerals) and a fluid density lower than 1 to compensate for incomplete flushing in the measurement zone. Density tools measure rock medium bulk density(b) in wellbore conditions.

Faust predicts . Well flowing 10,000 bpd.

Image logs, RCAL and SCAL tests are main tools to determine vugs, though all are costly and sometimes unavailable. Rho Fluid = 1.03 g/cc Calibrating density log with core porosity, used in certain companies.

Here we will use the density method.

Both the density and the neutron porosity for the wet clay point have been taken from the log readings in adjacent good shales.

Petrophysical Relationship to Predict Synthetic Porosity Log* ... Log transforms can be used to predict synthetics log such as P-wave velocity, density, and porosity log. Since a total porosity system is more reliably calibrated to core and simpler to work in, this is the approach recommended for petrophysical evaluation.

density, and neutron logs are used to correct for the effects of the varying lithology. However, neutron porosity values are often compared with other sources to indicate either lithology or the possibility of fractures. TOTAL POROSITY (PETROPHYSICAL DEFINITION) ... •Combined neutron-density log porosity is closer to core porosity in mixed lithologies.

The sidewall neutron log sees only a small portion of the borehole wall and may be affected by borehole breakout in the same way as the density log.

Fig. Use effective porosity only to calibrate a permeability transform. This kind of porosity significantly affects the permeability, pressure drop and recovery factor in the reservoir. The final parameter estimated in … If there are conductive shales present, correct for these using total porosity and either the Waxman-Smits or Dual Water models to get water saturations.

Density shows water density in sump below perfs, oil density over perf interval.

The upper half of the perfs may have been ineffective or the reservoir quality is so poor that no flow can be expected. Spinner shows increasing cummulative production over lower half of perfs. There are several approaches to calculate porosity from petrophysical well logs. Gardner introduced relation of density and P-wave velocity (Gardner, 1974).