This digital dataset contains historical geochemical and other information for 45 samples of produced water from 38 sites in the Placerita and Newhall Oil Fields in Los Angeles County, southern California. Produced water is a term used in the oil industry to describe water that is produced from oil wells as a byproduct along with the oil and gas. The locations from which these historical samples have been collected include 17 wells, 6 storage tanks, and 15 unidentifiable sample sources. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for all 17 wells. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation for 13 of the wells is OG (oil/gas). The samples (16) associated with these wells likely represent produced water based on well designation and history, although samples from two wells (Dataset ID 23 and 32) are described as formation water. Four wells have a site type designation of "injectate" based on the current designated well use (INJ, injection; or WD, water disposal), but samples from two of the four wells (Dataset ID 31 and 35) likely represent produced or formation water as well history records indicate that sample collection predated conversion to (Dataset ID 31) or the commencement of (Dataset ID 35) use for water disposal. Limited information is available about historical samples from storage tanks and unidentifiable sample sources. These samples may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from the following sources: scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM) Underground Injection Control (UIC) program, analytical reports located within well history files in CalGEM's online Well Finder (WF) database, analytical reports available as PDFs (Portable Document Format) documents located on the State Water Resources Control Board GeoTracker (SWRCB-GT) website, and data compiled by the USGS for the National Produced Water Geochemical Database (USGS PWDB). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file identifying each site by name, the site location, basic construction information, and American Petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination of the sample (formation into which water was to intended to be injected for samples labeled as injectate), specific sample dates for each site, and an inventory of which constituent groups were sampled on each date; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, trace elements, dissolved organic carbon (DOC), naturally occurring radioactive material (NORM), tracers, semi-volatile organic compounds (SVOCs), volatile organic compounds (VOCs), hydrocarbons, and organic acids. Ion (charge) balance calculations and percent error of these calculations were included for samples having a complete suite of major ion analyses. Analytical method, reporting level, reporting level type, and supplemental notes were included where available or pertinent. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

​​​​​​​​The Geologic Energy Management Division's (CalGEM) online mapping application Well Finder presents California’s oil and gas industry information from the geographic perspective. You can find and locate oil and gas wells and other types of related facilities throughout the state. Search by address, latitude/longitude, unique well number (also known as “API”), Public Land Survey System (PLSS) township/range/section, or by oil and gas field names. Dig deeper into individual well records. Explore where permits have been issued for oil and gas operations. Investigate wells by their type of use, such as oil and gas producers versus injectors.

Well Finder is a tool CalGEM provides to improve informational transparency. Readily available data contributes to better health and environmental safeguards--fundamentals of the CalGEM mission. Data can help inform California's efforts to achieve the twin goals of mitigating climate change and a net-zero footprint.

Well Finder interfaces with CalGEM’s online Well Statewide Tracking and Reporting System (WellSTAR) database and is updated nightly.

This digital dataset contains historical geochemical and other information for 200 samples of produced water from 182 sites in 25 oil fields in Los Angeles and Orange Counties, southern California. Produced water is a term used in the oil industry to describe water that is produced as a byproduct along with the oil and gas. The locations from which these historical samples have been collected include 152 wells. Well depth and (or) perforation depths are available for 114 of these wells. Sample depths are available for two additional wells in lieu of well or perforation depths. Additional sample sites include four storage tanks, and two unidentifiable sample sources. One of the storage tank samples (Dataset ID 57) is associated with a single identifiable well. Historical samples from other storage tanks and unidentifiable sample sources may also represent pre- or post-treated composite samples of produced water from single or multiple wells. Historical sample descriptions provide further insight about the site type associated with some of the samples. Twenty-four sites, including 21 wells, are classified as "injectate" based on the sample description combined with the designated well use at the time of sample collection (WD, water disposal or WF, water flood). Historical samples associated with these sites may represent water that originated from sources other than the wells from which they were collected. For example, samples collected from two wells (Dataset IDs 86 and 98) include as part of their description “blended and treated produced water from across the field”. Historical samples described as formation water (45 samples), including 38 wells with a well type designation of OG (oil/gas), are probably produced water, representing a mixture of formation water and water injected for enhanced recovery. A possible exception may be samples collected from OG wells prior to the onset of production. Historical samples from four wells, including three with a sample description of "formation water", were from wells identified as water source wells which access groundwater for use in the production of oil. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file identifying each site by name, the site _location, basic construction information, and American petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination (formation into which water was to intended to be injected for samples labeled as injectate) of the sample; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

This online map represents oil and gas wells in the CalGEM Well Statewide Tracking and Reporting System, or WellSTAR. Wells are displayed by well type and well status.

This digital dataset contains historical geochemical and other information for 271 samples of produced water from 143 sites in or near the San Ardo Oil Field in Monterey County, central California. Produced water is a term used in the oil industry to describe water that is produced from oil wells as a byproduct along with the oil and gas. The locations from which these historical samples have been collected include 101 wells; three wells (DataSet_ID 118 ,125, and 130) are located outside of the administrative boundary, but closer to San Ardo (within 3 miles) than any other oil field, and therefore they were included in this dataset. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 97 of these wells. Additional sample sites include 11 storage tanks, and 31 unidentifiable sample sources. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation of most of the wells (79) is OG (oil/gas) and the samples (188) associated with these wells represent produced water. Samples from two wells (Dataset ID 28 and 130) are described as formation water. One well (Dataset ID 30) was drilled as a water-source well (WS) and used to supply groundwater in support of oil production at the time it was sampled, but later converted to an injection well. Another well (Dataset ID 103) was originally drilled as an oil well, but later abandoned and converted to an irrigation well prior to sampling. Eighteen wells have a site type designation of "injectate" based on the sample description combined with the designated well use at the time of sample collection (SF, steam flood; WD, water disposal; or WF, water flood). Most of the historical samples associated with injectate sites may represent water that originated from sources other than the wells at which they were collected. However, samples from two of these wells (Dataset ID 16 and 76) likely represent produced water as they were sampled prior to the wells being used for injection. Limited information is available about historical samples from storage tanks and unidentifiable sample sources, but these may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file identifying each site by name, the site _location, basic construction information, and American petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination (formation into which water was to intended to be injected for samples labeled as injectate) of the sample; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

This online map provides the locations of submitted Well Permit records from CalGEM’s Well Statewide Tracking and Reporting System (WellSTAR) database. Records contain attributes related to the related applications and permits and associated wells.CalGEM is the Geologic Energy Management Division of the California Department of Conservation, formerly the Division of Oil, Gas, and Geothermal Resources (as of January 1, 2020).WellSTAR homepageUpdate Frequency: As Needed

This digital dataset contains historical geochemical and other information for 481 samples of produced water (PW) from 408 sites in the Edison, Mountain View, and Ant Hill Oil Fields in Kern County, California. Produced water is a term used in the oil industry to describe water that is produced from oil wells as a byproduct along with the oil and gas. The locations from which these historical samples have been collected include 199 wells, 67 sumps, 43 storage tanks (not associated with a specific well), and 104 unidentifiable sample sources which could not be classified because of insufficient information. The wells include 176 sites identifiable by an API (American Petroleum Institute) number and 23 sites for which an API designation could not be found, but which based on the water chemistry data source, site name, sample description, or other ancillary information have been classified as wells. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval or zone produced, are available for 177 of these wells. Sites representing sumps and storage tanks were classified in a similar manner as wells based on the water chemistry data source, site name, sample description, or other ancillary information. Numerical water chemistry data were compiled from six data sources: 1) California Geologic Energy Management Division (CalGEM) Aquifer Exemptions (AE) Status webpage analytical reports (CalGEM, 2016), 2) CalGEM archived analytical reports (CalGEM, 2021), 3) CalGEM Underground Injection Control (UIC) program hard copies of laboratory analytical reports (CalGEM-UIC, 2017), 4) CalGEM's online Well Finder (WF) database of well history files (CalGEM-WF, 2022), 5) California State Water Resources Control Board GeoTracker (SWRCB-GT) online data portal analytical reports (SWRCB-GT, 2022), and 6) three California Department of Water Resources (CDWR) historical reports with water-chemistry data for samples from oil-producing zones of wells (characterized as "formation" water) and wastewater disposal sumps (CDWR/CVRWQCB-E, 1953; CDWR/CVRWQCB-M, 1956; and CDWR/CVRWQCB-A, 1957). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the laboratory analysis reports and well history files from CalGEM-WF (2022). The compiled data are divided into two separate data files described as follows: 1) a summary data file (EMA_PW_Summary_Data.xlsx) identifying each site by name, the site _location, basic construction information, and American Petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination of the sample (formation into which water was to intended to be injected for samples associated with Site Type labeled as water disposal well), specific sample dates for each site, and an inventory of which constituent groups were sampled on each date; and 2) a data file of geochemistry analyses for selected constituents (EMA_PW_Geochemistry.xlsx) classified into one of the following groups: water-quality indicators, major and minor ions, nutrients, trace elements, naturally occurring radioactive material (NORM), volatile organic compounds (VOCs), and hydrocarbons. Ion (charge) balance calculations and percent error of these calculations were included for samples having a complete suite of major ion analyses. Analytical method, reporting level, reporting level type, dilution factor, and supplemental notes were included where available or pertinent. A data dictionary (EMA_PW_Data-Dictionary. xlsx) describes the geochemistry data file and is provided with this data release.

This digital dataset contains historical geochemical and other information for 89 samples of produced water from 84 sites in the Santa Maria Valley Oil Field in Santa Barbara County, California. Produced water is a term used in the oil industry to describe water that is produced from oil wells as a byproduct along with the oil and gas. Additionally, 3 samples from 3 sites that represent source water used in support of oil production were included in this dataset, for a total of 92 samples and 87 sites, respectively. The locations from which these historical samples have been collected include 27 wells, 2 reservoirs, 10 storage tanks, and 49 unidentifiable sample sources. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 25 of the 27 wells. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation for 23 of the wells is OG (oil/gas). The 27 samples associated with these wells likely represent produced water based on well designation and history. One of the 27 samples is a composite from two wells represented by Dataset ID 46. Three wells have a site type designation of "injectate" based on the current designated well use (WD, water disposal; or WF, water flood). The samples associated with these sites are of unknown origin, but likely represent produced water from OG wells in the Santa Maria Valley Oil Field. The two reservoir samples (Dataset_ID 53 and 54) are freshwater sources that were used in support of oil production, including one reservoir (Dataset_ID 54) described as supplied by groundwater wells. Limited information is available about historical samples from storage tanks and unidentifiable sample sources. These samples may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from the following sources: scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM) Underground Injection Control (UIC) program, analytical reports located within well history files in CalGEM's online Well Finder (WF) database, analytical reports available as PDFs (Portable Document Format) documents located on the State Water Resources Control Board GeoTracker (SWRCB-GT) website, and data compiled by the USGS for the National Produced Water Geochemical Database (USGS PWDB). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file identifying each site by name, the site _location, basic construction information, and American Petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination of the sample (formation into which water was to intended to be injected for samples labeled as injectate), specific sample dates for each site, and an inventory of which constituent groups were sampled on each date; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), hydrocarbons, and organic acids. Ion (charge) balance calculations and percent error of these calculations were included for samples having a complete suite of major ion analyses. Analytical method, reporting level, reporting level type, and supplemental notes were included where available or pertinent. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed historical produced water chemistry data and ancillary oil well information at the Buena Vista, McKittrick, and Cymric Oil Fields in the southwestern San Joaquin Valley (SWSJV), Kern County, California. Historical water chemistry data provide information on the salt mass balance of produced water disposed of on land, and in particular, chloride which is a conservative, nonreactive tracer. Data were compiled from the California Geologic Energy Management Division (CalGEM) Underground Injection Control (UIC) scans of laboratory results for produced water samples, the CalGEM Well Finder database for oil and gas wells, and historical documents (Rogers, 1917; WZI; 1988). The SWSJV_geochem.csv dataset supplements previously compiled chemistry data by the USGS at the Midway-Sunset, Elk Hills, North Belridge, South Belridge, and Lost Hills Oil Fields (cross-referenced in this data release). The Fall1953_volumes_chemistry.csv dataset contains Fall 1953 water production volumes by lease and produced water sample results compiled from Rickett and Reaves (1954a-d) to provide a spatial understanding of historical disposal on land.

This online map provides the locations of submitted Well Stimulation Permit records from CalGEM’s Well Statewide Tracking and Reporting System (WellSTAR) database. Records contain attributes related to the related applications and permits and associated wells.CalGEM is the Geologic Energy Management Division of the California Department of Conservation, formerly the Division of Oil, Gas, and Geothermal Resources (as of January 1, 2020).WellSTAR homepageUpdate Frequency: As Needed

Analysis of ‘WellSTAR Notices and Permits: Well Permits’ provided by Analyst-2 (analyst-2.ai), based on source dataset retrieved from https://catalog.data.gov/dataset/3217b411-5bf5-46f9-b82f-d10e2d0913ae on 12 February 2022.

--- Dataset description provided by original source is as follows ---

--- Original source retains full ownership of the source dataset ---

This dataset contains geochemical and other information for 40 historical samples of produced water from the North Coles Levee Oil Field. Three of these samples are from commingled tanks containing produced water from multiple wells as noted in the “Remarks” column. Water that is produced as a byproduct of oil production is called produced water. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The data were transferred manually into a numerical dataset and organized by specific produced water chemical characteristics. Each sample is identified by its API (American Petroleum Institute) number, latitude and longitude, well name, formation name, perforation interval, and date tested. The geochemical analyses include major ions, some minor ions, total dissolved solids (TDS), pH, specific gravity, resistivity, electrical conductivity, and charge balance. The collection and analysis methods and circumstances under which the historical samples were collected cannot be fully known. The intent is to use these historical data in grouped analysis including many sample results, rather than detailed interpretation of each individual sample. Caution should be used in basing interpretations of the data on single sample results.

This digital dataset represents historical geochemical and other information for 58 sample results of produced water from 56 sites in the Orcutt and Oxnard oil fields in Santa Barbara and Ventura Counties, respectively, in southern California. Produced water is a term used in the oil industry to describe water that is produced as a byproduct along with the oil and gas. The locations from which these historical samples were collected include 20 wells (12 in the Oxnard oil field and 8 in the Orcutt oil field). The top and bottom perforations are known for all except one (Dataset ID 33) of these wells. Additional sample sites include 13 storage tanks, and 13 unidentifiable sources. Two of the storage tanks (Dataset IDs 8 and 54), are associated with one and two identifiable wells, respectively. Historical samples from other storage tanks and unidentifiable sample sources may also represent pre- or post-treated composite samples of produced water from single or multiple wells. Historical sample descriptions provide further insight about the site type associated with several of the samples. Eleven sites, including one well (Dataset ID 30), are classified as "injectate" based on the sample description combined with the designated well use at the time of sample collection (WD, water disposal). Two samples collected from wells in Orcutt (Dataset IDs 4 and 7), both oil wells with known perforation intervals, and one sample from an unidentified site (Dataset ID 56) are described as zone or formation samples. Three other samples collected from two wells (Dataset ID’s 46 and 49) in Oxnard were identified as water source wells which access groundwater for use in the production of oil. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file identifying each site by name, the site location, basic construction information, and American Petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination (formation into which water was to intended to be injected for samples labeled as injectate) of the sample; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

This digital dataset contains historical geochemical and other information for 266 samples of groundwater (GW) from 208 wells located within 3 miles of the Edison, Mountain View, and Ant Hill Oil Fields in Kern County, California. The sampled wells include water-supply wells used primarily for domestic, irrigation, and public uses; however, the specific water-supply use of 27 wells is unknown ('unk'). Three wells with water use denoted as 'WS' (water supply) were documented as having originally been used in support of oil production, or were converted from oil production wells to water-supply wells by the time they were sampled. Numerical water chemistry data were compiled from five data sources: 1) Kern County Public Health Services Department (KCPHSD, 2017), 2) California Department of Conservation's Geologic Energy Management Division (CalGEM) archived analytical reports (CalGEM, 2021), 3) CalGEM Underground Injection Control (UIC) program hard-copy records (CalGEM-UIC, 2017), 4) CalGEM's Well Finder (WF) online database (CalGEM-WF, 2022), and 5) the California State Water Resources Control Board GeoTracker online data portal (SWRCB-GT, 2020). These data sources include varying degrees of location and well construction information. Data were manually compiled into two separate files described as follows: 1) a summary data file (EMA_GW_Summary_Data.xlsx) that includes well identifiers, location, construction, the number of chemistry samples, the period of record, specific sample dates for each site, and an inventory of which constituent groups were sampled on each date, and 2) a data file of geochemistry analyses for selected constituents (EMA_GW_Geochemistry.xlsx) classified into one of the following groups: water-quality indicators, major and minor ions, nutrients, trace elements, naturally occurring radioactive material (NORM), and volatile organic compounds (VOCs). Ion (charge) balance calculations and percent error of these calculations were included for samples having a complete suite of major ion analyses. Parameter code, analytical method, reporting level, reporting level type, dilution factor, and supplemental notes were included where available or pertinent. A data dictionary (EMA_GW_Data-Dictionary. xlsx) describes the geochemistry data file and is provided with this data release.

This dataset has results and the model associated with the publication Ciulla et al., (2024). It contains a U-Net semantic segmentation model (unet_model.h5) and associated code implemented in tensorflow 2.0 for the model training and identification of oil and gas well symbols in USGS historical topographic maps (HTMC). Given a quadrangle map (7.5 minutes), downloadable at this url: https://ngmdb.usgs.gov/topoview/, and a list of coordinates of the documented wells present in the area, the model returns the coordinates of oil and gas symbols in the HTMC maps. For reproducibility of our workflow, we provide a sample map in California and the documented well locations for the entire State of California (CalGEM_AllWells_20231128.csv) downloaded from https://www.conservation.ca.gov/calgem/maps/Pages/GISMapping2.aspx. Additionally, the locations of 1,301 potential undocumented orphaned wells identified using our deep learning framework or the counties of Los Angeles and Kern in California, and Osage and Oklahoma in Oklahoma are provided in the file found_potential_UOWs.zip. The results of the visual inspection of satellite imagery in Osage County is in the file visible_potential_UOWs.zip. The dataset also includes a custom tool to validate the detected symbols in the HTMC maps (vetting_tool.py). More details about the methodology can be found in the associated paper: Ciulla, F., Santos, A., Jordan, P., Kneafsey, T., Biraud, S.C., and Varadharajan, C. (2024) A Deep Learning Based Framework to Identify Undocumented Orphaned Oil and Gas Wells from Historical Maps: a Case Study for California and Oklahoma. Accepted for publication in Environmental Science and Technology. The geographical coordinates provided correspond to the locations of potential undocumented orphaned oil and gas wells (UOWs) extracted from historical maps. The actual presence of wells need to be confirmed with on-the-ground investigations. For your safety, do not attempt to visit or investigate these sites without appropriate safety training, proper equipment, and authorization from local authorities. Approaching these well sites without proper personal protective equipment (PPE) may pose significant health and safety risks. Oil and gas wells can emit hazardous gasses including methane, which is flammable, odorless and colorless, as well as hydrogen sulfide, which can be fatal even at low concentrations. Additionally, there may be unstable ground near the wellhead that may collapse around the wellbore. This dataset was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of California.

This online map provides the locations of wells that have been stimulated under an approved Well Stimulation Permit. The map display also provides information related to the well/stimulation treatment including: operator, field, well type, permit number, stimulation type, and the amount of base fluid used.CalGEM is the Geologic Energy Management Division of the California Department of Conservation, formerly the Division of Oil, Gas, and Geothermal Resources (as of January 1, 2020).WellSTAR homepageUpdate Frequency: As Needed

The U.S. Geological Survey (USGS), in cooperation with the California State Water Resources Control Board (SWRCB), compiled Fall 2017 fluid level elevation data from idle oil and gas wells in the Oxnard Oil Field to estimate vertical hydraulic head difference between oil production and overlying groundwater aquifer zones. Fluid elevations came from two sources, measurements in idle oil and gas wells and groundwater elevations in water wells in the overlying aquifer estimated at the points of idle well measurements using geographic information system (GIS) procedures. The fluid elevations from idle oil and gas wells were compiled by the California Geologic Energy Management Division (CalGEM) as part of their Idle Well Program; oil producers take the measurements and submit the data to CalGEM. These oil wells are perforated in the oil producing zones which includes the Vaca Tar Sands. Fluid elevations from the shallower groundwater system were extracted using GIS procedures at the locations of these idle oil and gas wells from a groundwater elevation contour map for Fall 2017 provided by the United Water Conservation District (UWCD). Groundwater elevation contours were calculated by UWCD from water-level measurements in groundwater wells monitored seasonally in the Oxnard Plain groundwater sub-basin and adjacent sub-basins. The groundwater elevation contours represent the lower aquifer system in the Oxnard Plain groundwater sub-basin and overlie the oil zone including Vaca Tar Sands. The fluid elevations in idle oil wells and calculated groundwater level elevations at the same location were compared to estimate vertical differences in groundwater head to assess potential fluid flow direction. Of the 65 idle well locations where vertical head differences were calculated, 43 had head differences indicating upward fluid gradients (head higher in oil wells than groundwater), 21 had head differences indicating downward fluid gradients (head lower in oil wells than groundwater), and 1 had head differences too small to discern vertical differences (within +/- 2 m). These data were analyzed in an accompanying manuscript as part of the SWRCB oil and gas Regional Monitoring Program and the USGS California Oil, Gas, and Groundwater (COGG) Program to assess regional groundwater quality overlying and adjacent to the Oxnard Oil Field.

This map shows result from CalGEM’s orphan well screening and prioritization methodology for the phase 1 final: initial technical screening phase. This result will help to prioritize plug and abandonment of likely orphan and deserted wells in California, as part the Federal and State abandonment project.

This data maps 5,296 wells using their coordinates recorded in WellSTAR. Though there are a total of 5,338 wells identified on the screening and prioritization inventory, 42 of these do not have known surface locations and cannot be mapped. Data is static, last updated February 2023. Based on public feedback received, CalGEM constructed its final screening methodology by building on and making important modifications to Scenario 2, which focused on minimizing risk to communities and sensitive environments rather than a focus solely on disadvantaged communities (scenario 1) or well integrity and safety (scenario 3). Wells are informed by the regulatory criteria found in California Code of Regulations, title 14, section 1772.4, and data from CalEnviroScreen 4.0 and SB 535 Disadvantaged Communities information.Wells are categorized into five tiers 1-5. Tiers representing five segments under the normal distribution, with tier 1 representing the highest risk wells. In additions, for those 1460 wells for which CalGEM field staff were deployed to locate the well, and the well was determined to be inaccessible, they are categorized as “Inaccessible”. CalGEM will assess the reason for the well inaccessibility, whether any monitoring is needed of the well, and a plan for abandoning the well should it become accessible. There are 45 wells that have changed status to “plugged and abandoned” in 2023, some by operators, some by CalGEM, and with the use of Federal Infrastructure grant funding.

More detail about the points associated with each criterion is in a Screening Prioritization Methodology document that will be available on CalGEM's website.Additional resources: Contact CalGEMOrphanWells@conservation.ca.gov for further questions.