Summarizes Crossplots

After generating the ten crossplots, SSA presents a screen which summarizes the results from all the crossplots. Consistent on all the hydrocarbon crossplots, "wet" is shaded blue. On the q-plot the producible shaded area is red and on the density-neutron log gas crossover is shaded red. On the crossplot summary screen depths that shade red for the q-plot and not blue on the hydrocarbon indicating plots are the potential producing zones which merit further analysis.

Purple shading on the low Vcl plot cautions the user to check that the clays mat have a high CEC content. In such formations, standard water saturation models may not be reliable.

The crossplot summary screen provides analysts with a quick review to identify zones which may be productive.

Computes Effective Water Saturation

Once a zone has passed the criteria for falling in the producible region of the q-plot and appears hydrocarbon bearing, effective water saturations can be computed.  SSA selects several methods to compute Sw based upon the logging suite available, one method which uses Rsh and one method which does not use Rsh. Users can select other methods for computing water saturations and select the values from the model they feel is most accurate.

A crossplot of Rsh methods versus non-Rsh methods can be generated to aid users in determining if the clay is dispersed or laminar. The Fertl and Hammock correction of Rcl=0.4*Rsh can be made and the Sw values recomputed.

Water saturation methods available in SSA include: Waxman-Smits, Dispersed Clay, Dual Water, Simandoux, Modified Archie for Low Vcl formations, Poupon (or the Indonesian Method), Laminar Shale, Dielectric Log, Automatic Compensation, Dual water - No Porosity Log, Fetrl, Ratio, and Automatic Compensation - No Porosity Log.

Calculates Net Pay

After water saturation is computed, net pay can be computed from user-defines cutoffs for clay volume, effective porosity, and effective water saturation.  All of the results for the analysis are summarized on the net pay screen. Besides net pay thickness, average values for clay volume, effective porosity, effective water saturation, and hydrocarbon pore feet are displayed.

Graphically the net pay screen gives six graphs. The first gives the volume of clay and sand, the second gives total and effective porosity, the third graph shades percent water and hydrocarbon, the fourth graph shades volume, sand volume, pore volume, water volume and hydrocarbon volume, the fifth graph represents gas from the neutron-density crossover, and the sixth graph shows hydrocarbon presence defined by the Dielectric log if available. Consecutive depths which satisfy the cutoff criteria are highlighted.  This screen provides a summary of the complete analysis showing  at a glance the potential commercial zones.