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Petroleum

Software

Select Pore Model and Calculate Cementation Exponent, m

A pore type review screen is provided to summarize the results of the five pore type crossplots. Four columns are provided, one for each pore type, that shows what depths and zones in the crossplot indicate that particular pore type. Used collectively, the columns summarize the crossplots and easily which zones are intercrystalline, vuggy, fractured, or bimodel. A resulting pore-type column shades the "most likely" pore type.

Once the pore type is known, the correct m model can be used. Since the carbonate reservoir may have more than one pore type at different depths, a model is selected for each pore type found on the zone. For intercrystalline reservoirs, the low porosity m model is used. For vuggy reservoirs the Nugent or Focke and Nunn methods are suggested.  For fractured reservoirs either the low porosity m or the Rasmus Model can be used and those reservoirs displaying bimodel pore type should use the W technique. Also for all of the pore type reservoirs alternatively the users could simply input m (eg m=2) or input a por-m transform equation.

View Hydrocarbon Plots

Knowing if a potential producing zone is hydrocarbon bearing is imperative to deciding if a well well be successful. CBA provides several crossplots to aid analysts in evaluating data. The PorD vs. PorN crossplot shows crossover evidence of a gas bearing zone.  Swa-Swr and the Dew Plot show if data plot in a wet zone. The Bulk Volume Water Plot shows if data plots in the wet or bimodel zone and if data is at irreducible water saturation. The Moved Hydrocarbon Plot shows if the zone is wet or if oil is not movable due to low permeability. The PRI Plot displays if a zone is in the water or hydrocarbon region. When an EPT log is available, this crossplot can also be used to shop if a zone is wet or hydrocarbon bearing.

To aid users in summarizing information from the hydrocarbon crossplots, a review screen give a column for each of the crossplots with depths in the wet regions shaded blue. Quickly log analysts can view the depths that may be hydrocarbon bearing and need further water saturation calculations.

Compute m, Sw, and Net Pay

Once a formation appears hydrocarbon bearing and the m and n values have been determined, users can compute water saturations and net pay.  On the water saturation screen a table giving Archie's water saturation, m, water saturation using the Carbonate methods (Archie's with a variable m), and water saturation from the Ratio method is displayed. A graph of the three water saturation values is also shown. The user can select which water saturation value to use in the net pay calculation.