The SPWLA Permian Basin Chapter

Technical Lunch and Learn
Tuesday, April 23, 2024 at 11:30 - 1:00 PM CST
Bush Convention Center
Downstairs Meeting Rooms

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“Predicting geomechanical properties of mudrocks at the basin-scale: examples from the Wolfcamp
and Spraberry formations in the Midland Basin

By: Shuvajit Bhattacharya, Ph.D.

Regional mapping and 3D geocellular modeling of geomechanical properties greatly benefit unconventional resource development. However, this comes with many challenges, including the need for appropriate and good-quality data with adequate vertical and areal coverage, comparable data vintages, etc. We present an integrated methodology to estimate and map different geomechanical properties of the Wolfcamp-Spraberry interval across the entire Midland Basin. Our method integrates well logs, core (triaxial tests), petrophysical inversion-based multi-mineral models, and class-based machine learning. We utilize a long short-term memory (LSTM) network for machine learning.
We estimated and mapped Young’s modulus, Poisson’s ratio, bulk modulus, and shear modulus of the Wolfcamp-Spraberry interval. The machine learning results showed approximately 0.97 accuracy and a root-mean-squared error of 7.0 in predicting shear sonic velocity used in log-based estimates from dipole sonic logs. There are uncertainties in log-based estimates when dealing with only compressional sonic logs and limited triaxial tests. We use triaxial data to convert log-based dynamic properties to static geomechanical properties. Lithologies control geomechanical properties; however, the differences in geomechanical responses are smaller in the case of mixed lithologies. Extensive data QA/QC, wide coverage of wells, and a good understanding of the basin geology are needed for meaningful model training; otherwise, the prediction can be poor. Additionally, model performance is affected if data from the southern Midland Basin is used to predict rock properties in the central and northern parts of the basin, and the reverse is true as well; this indicates varying geologic controls.

Speakers Biographies:
Dr. Shuvajit Bhattacharya is a Research Scientist at the Bureau of Economic Geology, University of Texas at Austin. He has expertise in petrophysics, quantitative seismic, and machine learning applications. He has worked on multiple projects on unconventional reservoirs, CCS, geothermal, and hydrogen storage. He received the SEG's J. Clarence Karcher Award in 2022 and the AAPG Gulf Coast Section's A.I. Levorsen Award in 2023 for outstanding scientific contributions. He completed a Ph.D. from West Virginia University in 2016.


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Permian Basin Chapter of the SPWLA

Next Meeting: 
May 28, 2024

Monthly Meetings: 4th Tuesday of Most Months

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President: Veronica Montoya 
Vice President of Technology: Chris Smith
Communications: Kate La Fleur
Jennifer Reeves
Sebastian Ramiro-Ramirez