Global Petrophysical Definitions1
| With this feature... | Do this... |
|---|---|
| Enable | Select whether to apply a petrophysical definition. |
| Group | This setting is reserved for possible future functionality to group and activate templates by field or exploration area. |
| Name | Type a zone name directly in the cells. The name can be anything. |
| From | To | Click to display the Formation Lookup dialog box where you type the formation name to insert. |
| Above | Below | Type a negative or positive depth at which to start and stop the reading based on the formations selected above. |
| Clean, GR | Type a value used to calculate VShale from Gamma Ray. VShale is 0 where Gamma Ray is less than Clean Rock. |
| Shale, GR | Type a value used to calculate VShale from Gamma Ray. VShale is 100% where Gamma Ray is greater than Shale. |
| PHI From | Select the log from which porosity is used to calculate Phi. Where there are multiple logs listed a hierarchy search occurs where the first log in the sequence is used. If it's not available, the second log is used. If it's not available, the third log is used. |
| Sw From | Select the log from which water saturation is calculated. Options are Deep resistivity, Induction, or Laterolog. |
| Sw Method | Select the equation used to calculate water saturation. Archie is preferred for relatively clean rock where VShale is less than 20 to 25%. Modified Simandoux is preferred for shaly rocks. |
| Rw. ohm | Type the formation water resistivity for surface conditions. This value can be obtained from atlases, DTS reports, etc. It is used to calculate water saturation. AccuLogs automatically applies temperature correction to Rw for each well based on the actual depth and temperature gradient. |
| Rclay | Type the clay (shale) resistivity in OHHM, which is used for the Simandoux equation. |
| Dmx, kg/m3 | Type the matrix density, which is used to calculate Phi from bulk density. Note that clicking the buttons in the Set Zone Matrix pane below overwrites a value you type here. |
| Dfl, kg/m3 | Type the fluid density, which is used to calculate Phi from bulk density. The default is 1,000 kg/m3 for fresh mud. |
| Dclay, kg/m3 | Type the clay density, which is used to correct Phi for the presence of clays. The default is 2,450 kg/m3, which falls between 2,200 for wet clay and 2,700 for very dry clay. |
| DTmx, ms/f | Type the matrix DT, which is used to calculate Phi from DT. The default is 55 ms/f for quartz matrix. Note that clicking the buttons in the Set Zone Matrix pane below overwrites a value you type here. |
| DTfl, ms/f | Type the fluid DT, which is used to calculate Phi from DT. The default is 189 ms/f for fresh mud. |
| DTclay, ms/f | Type the clay DT, which is used to correct Phi from DT for the presence of clays. The default is 70 ms/f. |
| Compaction Factor | Type the value used to correct for Phi from DT for unconsolidated rocks. The default is 1 for consolidated rocks. For unconsolidated rocks, if DTshale (ms/f) is greater than 100, the Compaction Factor is DTShale divided by 100. |
| NPHIclay, % | Type the clay hydrogen index, which is used to correct Neutron Porosity for the presence of clays. The default is 18%. |
| VSH CUT, % | Type the VShale cut off. Effective Phi is 0 where VShale is greater than VSH CUT. The default is 30%. |
| Bad Hole, mm | Type the bad hole cut off. Effective Phi is 0 where the borehole diameter from the caliper log is greater than the Bad Hole value. The default is 275 mm. |
| A | Type the tortuousity or formation factor, which is used in the Archie and Simandoux equations to calculate water saturation. The default is 0.81. |
| M | Type the cementation factor, which is used in the Archie and Simandoux equations to calculate water saturation. Average M values for some sedimentary rocks: Unconsolidated Sand = 1.3; Very Slightly Cemented Sand = 1.45; Slightly Cemented Sand = 1.65; Moderately Cemented Sand = 1.85; Highly Cemented Sand = 2.0; Intergranular Carbonate = 2.0; Fractured Carbonate = 1.4; Vuggy Carbonate = 2.3; Moldic Carbonate = 3.0; The default is 2. |
| N | Type the saturation factor, which is used in the Archie and Simandoux equations to calculate water saturation. The default is 2. |
| Suppress Coal | Select whether Effective Phi is 0 for detected coal beds where: Gamma Ray is less than CoalMaxGR. The default is 75 GAPI. Density is less than CoalMaxDens, kg/m3. The default is 1,960 kg/m3. DT is greater than CoalMinDT, ms/f. The default is 110 ms/f. To detect coal beds, AccuLogs mainly uses Gamma Ray and Density logs. Sonic DT is used if no bulk density is detected within the zone. |
| Set Zone Matrix | Select the matrix type, which controls the values that appear in the Density matrix (Dmx) and the Delta T matrix (DTmx). By default, Quartz is used. Note that the matrix options use the most common industry-standard values; however, you can change this value by typing directly in the Dmx and DTmx cells that appear in the grid. |