Calculation of well logs is a time consuming process. This template uses input parameters which consist of well name, location, county, state, formation name, starting depth, repeat interval, resistivity of shale, and irreducible bulk volume water which provides heading information for print outs. Required information from basic well logs are porosity, conductivity (optional), formation resistivity, resistivity of the formation water for the zone being calculated, resistivity of the mud filtrate, the porosity cutoff for pay in the zone being calculated and the salt water saturation cut off for the pay zone. These parameters are used to calculate apparent water resistivity, salt water saturation, bulk volume water, ratio of apparent water resistivity to input water resistivity, irreducible salt water saturation, resistivity volume of shale and a derived porosity value. A hard copy print out of the results is available through the Lotus (is a registered trademark of Lotus Development Corporation) print function. Using this template allows maximum control of the input parameters and reduces hand calculation time.


Basic information such as well name, location, county, state, formation being calculated, comments and initial potential are not used in calculating well logs. A place for this information is provided solely for reference when print outs are made of the finished work sheet.

Starting depth and repeat interval (depth between calculations) are required parameters. Starting depth is used in conjunction with the repeat interval to generate depth figures. The resistivity of the formation water (Rw) and the resistivity of the mud filtrate (Rmf) are necessary for the calculation of logs. They are input as decimal values. These figures are used in several of the formulas. Rw can generally be determined from an Rw listing for an area. Rmf is found on the well log heading and should be corrected for formation temperature.

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