Water Resources Group
I currently have funding (tuition plus stipend) for one MS student starting Fall 2024 or Spring 2025. We do not have a PhD program at Sacramento State. While our formal application deadline is March 1, 2024, late applications can be submitted through March 8, 2024 by contacting me at dhs@csus.edu
We’re currently looking for prospective MS students that hold (or will hold) a bachelors in geology. Coursework in GIS, hydrogeology, geochemistry, and geophysics is useful but not necessary. All projects will require the use of the Python programming language but don’t let this scare you away as we can teach you from scratch. Note that our graduate program requires 2nd semester Calculus and Chemistry but these can be completed during the first year of our program.
Future MS student projects could involve one or more of 1) mapping the salinity of groundwater in and around oil fields using borehole geophysical logs, 2) mapping the network of permeable sand layers that connect wells and aquifers, 3) documenting the evolution of water chemistry in aquifers through temporal changes in geophysical log response, and 4) quantifying the role of well integrity problems that may allow vertical transmission.
My Water Resources Group investigates potential connections between oil and gas production and potentially usable groundwater in California. We are funded by the California State Water Resources Control Board Regional Monitoring Program and US Geological Survey California Water Science Center. You can find more information about our research partners at the California Oil, Gas, and Groundwater program here.
Figure from Stephens et al. (2018) showing a cross section of groundwater salinity, measured in ppm total dissolved solids, mapped using borehole geophysical logs.
Our general approach is to use publicly available oil and gas well log records from the California Geologic Energy Management Division (CalGEM) to understand the 3-d relationship between stratigraphy, groundwater, and petroleum-production systems. We use borehole geophysical logs (resistivity, spontaneous potential, porosity) to map out the geologic framework of permeable rock and confining layers and to estimate groundwater salinity using petrophysical equations such as Archie’s equation. We then use detailed well construction histories to understand the depth of oil production and fluid/steam injection from casing perforations and the extent of physical barriers such as casing, annular cement, and plugs that prevent horizontal or vertical fluid migration. Visualization of the combined 3-d stratigraphic-groundwater-petroleum system can then be used to understand risk to potential usable groundwater. Our work is then presented to the California State Water Resources Control Board where it is used to inform regulatory decisions.
All of our data is collected by our Water Resources Group, an amazing group of undergraduate and graduate students directed and managed by Theron Sowers. The primary data which we use only exists as CalGEM well records consisting of millions of pages of scans. Our students read through these documents, some of which are hundreds of pages and extend back into the 1800s, and extract important well construction data enabling us to have a better idea of potential threat to groundwater.
Example current and previous MS research projects:
Amanda Howery, MS 2021, now at the California State Water Resources Control Board, mapped 4-d temperature in aquifer and reservoir in the thermally stimulated San Ardo Oil Filed using borehole temperature logs. She found anomalously high temperatures in the shallow groundwater system which may be caused by integrity issues in . Her thesis work is being incorporated into two papers, one of which is in review and another in preparation.
Michael Flowers, MS 2020, now at the California State Water Resources Control Board, mapped out groundwater TDS and stratigraphy in the shallow aquifer in the North Coles Levee Oil Field using borehole geophysical logs. He discovered a salinity reversal, where groundwater salinity decreases with depth, explaining it as a consequence of shoreline paleogeography. His thesis work was later published as Flowers et al. (2022).
Figure from Flowers et al. (2022) showing the relationship between groundwater salinity, measured in ppm total dissolved solids, and stratigraphy. Note that salinity decreases with depth below the base of the San Joaquin Formation. This is interpreted by Flowers et al. (2022) due to a change in connate water composition linked to a evolution of an open deltaic system into a restricted mudflat environment.
Michael Stephens, MS 2017, now Research Geologist at US Geological Survey California Water Science Center) used archived borehole geophysical logs and measured geochemistry to map aquifer salinity structure in the Fruitvale and Rosedale Ranch oilfields near Bakersfield. A key part of this project was determining values for empirical constants in Archie's equation by mathematical optimization based on measured geochemistry. His thesis work was later published as Stephens et al. (2018).
Other select publications from the group: