Stresslog

A libre application to calculate and plot pore pressure and other geomechanical data from las files. It is intended for pre-drill and post-drill studies of wells, and can be used for rudimentary semi-realtime stress prediction (for example if the wellsite geologist fetches and updates the las from MWD/LWD provider every single or so).

Features

• Import las files, deviation files, ucs and lithology files

• Alias logs using user modifiable alias file

• Pad log data all the way to surface, using appropriate KB, GL or WD values (Option to specify these and correct these in the Log Header)

• Auto export the well data as .csv, so you can run your own plots and calculations in your software of choice

• Calculate Pore Pressure, Shmin, SHMax, Sv and UCS from DT

• Model saved to and read from model.csv, calibrate model on analog well and run it on current well using sonic velocity from seismic and/or LWD/MWD data

• Plot Stress Polygon, Wellbore Stability and Kirsch Plots at drainhole analysis depth

• Plot the data in user configurable intervals

• Option to save Plots at custom DPI at 1200 dpi

• Option to output Las Files (with updated header and new data columns)

• Fields for adding mud data, loss/gain data and other data interpreted from drilling and testing history, these are plotted over the calculated data to help visually constrain the model

• Option to include ascii file with observations from resistivity image logs (or others like ultrasonic calipers) to include tensile fractures and breakouts, which are then used internally to better constrain SHMax

• Override nu, mu, and UCS from the lithology file

Installation

You can download the setup file from the release section, and install it like any normal program.

Or, you can compile from source. To compile from source, you need toga and briefcase packages in your python environment.

pip install toga
pip install briefcase

Once these are installed, you can build using the briefcase commands from the folder containing the pyproject.toml file

briefcase create
briefcase build
briefcase package

For more help, consult the BeeWare documentation.

Acknowledgements

Jon Jincai Zhang, for his awesome work on pore pressure prediction, and geomechanics at large. This software uses his algorithms wherever possible.

In more detail: The Stability Analysis Plots are after Peska and Zoback, 1995. The Stress Polygon Technique for constraining SHMax is after Zoback et al., 2003 The Pore Pressure equation is from Zhang, 2011 The shmin is calculated in accordance with Dianes, 1982, as well as Zoback and Healy,1992

This software is written in Python, using the python library Welly by Agile Scientific, Canada. Welly itself uses the Lasio library to handle the las files. The GUI is written using Toga, and built using Briefcase, which are both components of the BeeWare Project. Other libraries used include Pandas, Numpy, Matplotlib and PIL.

Disclaimer

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