1 Investigations of Hydrologic Resources in the Cordillera

Wednesday, 2 April 2025
8:00 AM - 12:00 PM
Granada/Hermosa

DRY HOLES OUTSIDE OF CALIFORNIA OIL AND GAS FIELDS AS POTENTIAL UPWARD MIGRATION PATHWAYS FOR DEEPER, MORE SALINE FLUIDS

Paper number: 1-10
Program: Theme Sessions
Time: 11:00 AM – 11:20 AM

Authors

Abstract

In California, more than 11,000 oil and gas wells that did not produce economically viable amounts of hydrocarbons (termed “dry holes”) are located outside of established oil and gas field boundaries. Many of these wells were drilled and almost immediately abandoned, often leaving boreholes that were partially or completely uncased and unplugged. While in some cases, plugs were placed across critical zones, such as the base of fresh water, significant extents of open, uncased boreholes remain. These open boreholes may act as vertical conduits for fluid migration, potentially connecting deep, saline aquifers with shallow, usable water. This potential is increased with changes to hydraulic head in shallow aquifers caused by nearby groundwater pumping.

To assess the potential for fluid migration, drilling, casing, and plug data were collected for all dry holes outside of oil and gas fields in two key regions in California: Kern County (n=1,297) and the area around Sacramento (n=439). These data were then compared to the completed depths of water wells in proximity to the oil and gas wells. Results show these dry holes have long extents of open borehole between plugged intervals. In some cases, these sections are filled with drilling mud, however in many wells, they are simply left open. Some of these open boreholes extend above the deepest perforation of nearby groundwater wells, leaving open the possibility that groundwater pumping could induce migration of higher salinity fluids into fresher waters.

Geological Society of America Abstracts with Programs. Vol. 57, No. 4

doi: 10.1130/abs/2025CD-410283

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.