Collection Method

Collection Method Description

We use a combination of geophysical logging tools to interpret lithology from geophysical well logs. Generally, we evaluate geophysical well log lithology using a five-tier classification system. The five simplified classifications includes sand (100 percent sand), sand and clay (50 percent sand/50 percent clay), sand with clay (65 percent sand/35 percent clay), clay with sand (35 percent sand/65 percent clay), and clay (100 percent clay). Percentages are approximate and are used to assign a numerical value that can indirectly represent total porosity, or the total void space of the rock. Where we lack geophysical log data, lithologic descriptions from drillers logs are simplified, and assigned a percent sand value as described above.

Quality Control Level

Quality Assurance Description

QAQC checks are performed by TWDB BRACS staff to ensure all well header information is accurately captured. We also receive feedback from internal and external users regarding misplotted wells. Location checks are also performed on wells that appear misplaced. For a typical BRACS study, we prepare maps of net sand within the study area to represent the cumulative sand thickness and sand dispersal pattern using lithologic picks. The interpolated maps of net sand are reviewed within the context of regional geological structure and depositional environments for irregularities. Anomalies that resulted from erroneous well locations or lithologic picks are updated.

Spatial Coverage

Bounding Coordinates

• North: 36.57914
• East: -93.60762
• South: 25.77887
• West: -106.62922

Coordinate System

Spatial Description

Statewide in Texas

Disclaimer

The data provided in these files is accurate as of the date of the file. The TWDB provides this information as a public service in accordance with its statutory responsibility. Users of this data are responsible for checking the accuracy, completeness, currency, or suitability of the information for any particular purpose. The TWDB disclaims any liability for any claims or damages that may result from the use of this data.

Additional Information

Wells with lithologic records in the BRACS database. The source of lithology information is predominantly from interpretation of geophysical well logs from oil and gas wells, but also includes lithologic descriptions from drillers logs (field source_geologic_data).

Program Area

Supporting URLs

Data Contact Email