In Danomics Petrophysics Insights users are guided through a workflow that walks them through a number of modules. These modules are located via a dropdown menu at the top center of the window. The modules are listed in the order in which a user should ideally proceed through a project. However, this order is not strictly enforced and the user can start at any module and can seamlessly move both forward and back through the modules. This help article will focus on the Clay Volume module.
Clay Volume Module
To activate the Clay Volume module, select “Clay Volume” from the module dropdown selection menu located in the top-middle area of the page.
The Clay Volume module is intended to help users determine the volume of clay minerals present in an interval. Methods include:
- Vclay from Neutron-Density
- Vclay from Gamma Ray
- Linear method
- Larionov Young method
- Larionov Old method
- Clavier method
- Steiber method
- Vclay from SP
The formula for Vclay from Neutron-Density is:
(($rhob_clean2 - $rhob_clean1) * (@neutron_final - $nphi_clean1) - (@density_final - $rhob_clean1) * ($nphi_clean2 - $nphi_clean1)) / (($rhob_clean2 - $rhob_clean1) * ($nphi_clay - $nphi_clean1) - ($rhob_clay - $rhob_clean1) * ($nphi_clean2 - $nphi_clean1))
This requires six parameters from the user:
|Parameter Name||Parameter Description|
|rhob_clean1||Matrix Bulk Density value|
|rhob_clean2||Bulk Density value in a clean, high porosity zone|
|rhob_clay||Bulk Density value in a 100% clay zone|
|nphi_clean1||Matrix Neutron Porosity value|
|nphi_clean2||Neutron Porosity value in a clean, high porosity zone|
|nphi_clay||Neutron Porosity value in a 100% clay zone|
These parameters can be graphically selected via dragging and dropping parameters in a Neutron-Density crossplot, which is available with reference lines for common lithologies and clay types in the Crossplot tab.
Note that the solution is clipped to between zero and one.
Gamma Ray Methods
All of the Gamma Ray Methodologies require the user to select two parameters; gr_clean and gr_clay. These parameters correspond to the values of the gamma ray curve in a clay-free interval and in a 100% clay interval. Usually these parameters are adjusted so that the Vclay from GR and Vclay from Neutron-Density methods provide a similar solution. Below are the equations used in each of the six methods. Note that all calculations are clipped to zero and one. The parameters can be visually selected by dragging and dropping the parameter values in the Gamma Ray track on the well log panel.
Linear GR Method
(@gr_final - $gr_clean) / ($gr_clay - $gr_clean)
GR Larionov Young Method
0.083*(2^(3.7*((@gr_final - $gr_clean) / ($gr_clay - $gr_clean)))-1)
GR Larionov Old Method
0.33*(2^(2*((@gr_final - $gr_clean) / ($gr_clay - $gr_clean)))-1)
GR Steiber Method
0.5*((@gr_final - $gr_clean) / ($gr_clay - $gr_clean))/(1.5-((@gr_final - $gr_clean) / ($gr_clay - $gr_clean)))
GR Clavier Method
1.7-(3.38-(((@gr_final - $gr_clean) / ($gr_clay - $gr_clean))+0.7)^2)^0.5
The Vclay from SP method utilizes the following formula:
(@sp_final - $sp_clean)/($sp_clay - $sp_clean)
This requires the user to set two parameters, the sp_clean, and sp_clay parameters, which represent the value of the SP curve in a clean interval and a 100% clay interval. The parameters can be set by dragging and dropping the parameter lines present on the SP track in the well log panel.
Clay Volume Outputs
The final result, as well as the results from each independent method are available for use/export. The table below shows the relevant curve names
|Final Vclay Result (Volume of Wet Clay)||vwcl|
|Vclay from Neutron-Density||vcl_nd|
|Vclay from SP||vcl_sp|
|Vclay from GR (selected methodology)||vcl_gr|
|Linear GR method||vcl_gr_basic|
|GR Larionov Young||vcl_gr_ly|
|GR Larionov Old||vcl_gr_lo|