oil and gas – California Water Library

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Multiple-Well Monitoring Site Adjacent to the Lost Hills Oil Field, Kern County, California

U.S. Geological Survey (USGS) | February 20th, 2020

Summary

The U.S. Geological Survey (USGS), in cooperation with the California State Water Resources Control Board, is evaluating several questions about oil and gas devel

The U.S. Geological Survey (USGS), in cooperation with the California State Water Resources Control Board, is evaluating several questions about oil and gas development and groundwater resources in California, including (1) the location of groundwater resources; (2) the proximity of oil and gas operations and groundwater and the geologic materials between them; (3) evidence for or against fluids from oil and gas sources in groundwater; and (4) the pathways or processes responsible when fluids from oil and gas sources are present in groundwater (U.S. Geological Survey, 2019). As part of this evaluation, the USGS installed a multiple-well monitoring site in the southern San Joaquin Valley near Lost Hills, California, adjacent to the Lost Hills oil field. Data collected at the Lost Hills multiple-well monitoring site (LHSP) provide information about the geology, hydrology, geophysics, and geochemistry of the aquifer system, thus enhancing understanding of relations between adjacent groundwater and the Lost Hills oil field in an area where there is little groundwater data. This report presents construction information for the LHSP and initial geohydrologic data collected from the site.

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Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California

American Chemical Society (ACS) | August 7th, 2019

Summary

Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitva

Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitvale, Lost Hills, South Belridge). 226Ra+228Ra activities (range = 0.010–0.51 Bq/L) exceeded the 0.185 Bq/L drinking-water standard in 18% of the wells (not drinking-water wells). Radium activities were correlated with TDS concentrations (p < 0.001, ρ = 0.90, range = 145–15,900 mg/L), Mn + Fe concentrations (p < 0.001, ρ = 0.82, range = <0.005–18.5 mg/L), and pH (p < 0.001, ρ = −0.67, range = 6.2–9.2), indicating Ra in groundwater was influenced by salinity, redox, and pH. Ra-rich groundwater was mixed with up to 45% oil-field water at some locations, primarily infiltrating through unlined disposal ponds, based on Cl, Li, noble-gas, and other data. Yet 228Ra/226Ra ratios in pond-impacted groundwater (median = 3.1) differed from those in oil-field water (median = 0.51). PHREEQC mixing calculations and spatial geochemical variations suggest that the Ra in the oil-field water was removed by coprecipitation with secondary barite and adsorption on Mn–Fe precipitates in the near-pond environment. The saline, organic-rich oil-field water subsequently mobilized Ra from downgradient aquifer sediments via Ra-desorption and Mn/Fe-reduction processes. This study demonstrates that infiltration of oil-field water may leach Ra into groundwater by changing salinity and redox conditions in the subsurface rather than by mixing with a high-Ra source.

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Organic geochemistry and toxicology of a stream impacted by unconventional oil and gas wastewater disposal operations

Applied Geochemistry (Elsevier) | March 10th, 2017

Summary

The large volume of wastewater produced during unconventional oil and gas (UOG) extraction is a significant challenge for the energy industry and of environmental concern

The large volume of wastewater produced during unconventional oil and gas (UOG) extraction is a significant challenge for the energy industry and of environmental concern, as the risks due to leaks, spills, and migration of these fluids into natural waters are unknown. UOG wastewater is often hypersaline, and contains myriad organic and inorganic substances added for production purposes and derived from the source rock or formation water. In this study, we examined the organic composition and toxicology of water and sediments in a stream adjacent to an underground injection disposal facility that handles UOG wastewaters.

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Potential Impacts of Future Geological Storage of CO2 on the Groundwater Resources in California’s Central Valley: Southern San Joaquin Basin Oil and Gas Production Analog for Geologic Carbon Storage

California Energy Commission (CEC) | May 1st, 2013

Summary

This study investigated the potential impacts of the injection and storage of large quantities of carbon dioxide on shallow water resources in California’s southern San

This study investigated the potential impacts of the injection and storage of large quantities of carbon dioxide on shallow water resources in California’s southern San Joaquin Basin, including the possibility that if such injection was properly planned it might help mitigate the land subsidence impacts related to over-pumping of groundwater. The project used simulation studies to investigate whether the basin-scale pressure changes and brine displacement caused by future carbon dioxide storage in the deep sediments could impact the groundwater-surface water systems in the area. Two simulation models were developed. The Deep Basin Reservoir Simulation Model was developed for accurately simulating the multiphase processes of carbon dioxide and brine flow occurring in deep sequestration reservoirs. The Shallow Water Resources Impact Simulation Model was developed for accurately predicting the impact of deep carbon dioxide sequestration on a stressed water system, including evaluation of carbon dioxide-related impacts in the context of the long-term groundwater and subsidence trends occurring in the area as a result of other water stresses such as pumping and irrigation. The Deep Basin Reservoir Simulation Model showed that the caprock and overlying geological units had sufficient barrier attributes to prevent pressure propagation from the injection layer to the shallow aquifers. The Shallow Water Resources Impact Simulation Model simulation results showed that deep carbon dioxide injection would create only minor head change and surface uplift in the shallow model layers. Overall the simulation results suggested that even large carbon dioxide storage projects should have minimal impact on shallow groundwater and surface water systems if thick layers of shales and sands separated the deep CO2 injection layers from shallow aquifers. Researchers believed this study justified devoting resources to evaluating the potential impact from localized pathways or from induced seismicity to more thoroughly investigate the feasibility of carbon dioxide storage in the southern San Joaquin Basin.

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Prioritization of Oil and Gas Fields for Regional Groundwater Monitoring Based on a Preliminary Assessment of Petroleum Resource Development and Proximity to California’s Groundwater Resources

U.S. Geological Survey (USGS) | July 20th, 2018

Summary

The California State Water Resources Control Board initiated a regional monitoring program in July 2015 to determine where and to what degree groundwater quality may be a

The California State Water Resources Control Board initiated a regional monitoring program in July 2015 to determine where and to what degree groundwater quality may be adversely impacted by oil and gas development activities. A key issue in the implementation of the regional groundwater monitoring program is that each year, detailed characterization work can be done in only a few of California’s 487 onshore oil and gas fields. The first step in monitoring groundwater near petroleum development is to prioritize oil and gas fields using consistent statewide analysis of available data that indicate potential risk of groundwater to oil and gas development. The U.S. Geological Survey compiled data for four factors that characterize the intensity of petroleum resource development and proximity to groundwater resources: petroleum-well density, volume of water injected in oil fields, vertical proximity of groundwater resources to oil and gas resource development, and water-well density. An overall priority ranking for each field was determined by computing summary metrics, analyzing statewide distributions of summary metrics for all oil and gas fields, using those distributions to define relative categories of potential risk for each factor, and combining relative risk rankings for different factors into an overall priority ranking. This preliminary assessment does not represent an evaluation of groundwater risk to oil and gas development, which needs to be based on detailed analysis and data related to development activities including well stimulation, well integrity issues, produced water ponds, and underground injection. Based on the prioritization analysis, 22 percent (107 fields) of the total number of oil and gas fields in California were ranked as high priority, 23 percent (114 fields) as moderate priority, and 55 percent (266 fields) as low priority. These results indicate that between 100 and 200 oil fields are principal candidates for the next steps in the regional monitoring program. The land area of fields that ranked high priority accounted for 41 percent of the total field area (3,392 square miles). More than half of the high priority fields were in the southern San Joaquin Valley and the Los Angeles Basin. Some of the larger fields tended to have higher rankings because of greater intensity of petroleum development, sometimes coupled with proximity to groundwater resources. The U.S. Geological Survey, in collaboration with the California State Water Resources Control Board and other agencies, has begun regional groundwater monitoring near oil and gas fields selected for study through the California Oil, Gas, and Groundwater cooperative program. Groundwater monitoring includes compiling, analyzing, and developing three-dimensional visualizations of existing data, including geological frameworks, salinity mapping, identification of surface features that could potentially affect groundwater quality, locations and depths of oil/gas and water wells, cataloging well-construction integrity issues, and evaluating the directions of groundwater flow. These analyses are required to determine where existing wells should be monitored and where new monitoring wells may need to be drilled.

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Recommendations on Model Criteria for Groundwater Sampling, Testing, and Monitoring of Oil and Gas Development in California

California State Water Resources Control Board (SWRCB) | June 1st, 2015

Summary

In California Senate Bill 4 (Pavley, 2013; hereafter referred to as “SB4”), the California legislature found and declared that protecting the state’s groundwater f

In California Senate Bill 4 (Pavley, 2013; hereafter referred to as “SB4”), the California legislature found and declared that protecting the state’s groundwater for beneficial use, particularly sources and potential sources of drinking water, is of paramount concern. Access to safe drinking water is a major issue for California, especially to its disadvantaged communities. State policy is that every human being has the right to safe, clean, affordable, and accessible water adequate for human consumption, cooking, and sanitary purposes (Chapter 524, Statutes of 2012 (Assembly Bill 685, Eng)). SB4 further found and declared that strategic, scientifically based groundwater monitoring of the state’s oil and gas fields is critical to allaying the public’s concerns regarding well stimulation treatments of oil and gas wells.

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Regional patterns in the geochemistry of oil-field water, southern San Joaquin Valley, California, USA

Applied Geochemistry (Elsevier) | September 21st, 2018

Summary

Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gasfields are commonly used toexamine the source of the formation water and possible impact

Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gasfields are commonly used toexamine the source of the formation water and possible impacts on groundwater in areas of oil and gas de-velopment. Understanding the geochemical variability of oil-field water could help to evaluate its origin anddelineate possible contamination of shallow aquifers in cases where oil-field water is released to the environ-ment. Here we report geochemical and multiple isotope (H, C, O, Sr, Ra) data from 22 oil wells, three sources ofproduced water that are disposed of in injection wells, and two surface disposal ponds in four oilfields in thesouthern San Joaquin Valley, California (Fruitvale, Lost Hills, North and South Belridge). Correlations betweenCl andδ18O, as well as other ions, and gradual increases in salinity with depth, indicate dilution of one or moresaline end-members by meteoric water. The saline end-members, represented by deep samples (610 m–2621 m)in three oil-bearing zones, are characterized by NaeCl composition, near-seawater Cl concentrations (median20,000 mg/L), enrichedδ18OeH2O (median 3.4‰), high ammonium (up to 460 mg-N/L), and relatively highradium activity (226Ra+228Ra = 12.3 Bq/L). The deepest sample has low Na/Cl (0.74), high Ca/Mg (5.0), andlow87Sr/86Sr (0.7063), whereas the shallower samples have higher Na/Cl (0.86–1.2), Ca/Mg near 1, and higher87Sr/86Sr (∼0.7083). The data are consistent with an original seawater source being modified by various depthand lithology dependent diagenetic processes. Dilution by meteoric water occurs naturally on the east side of thevalley, and in association with water-injection activities on the west side. Meteoric-waterflushing, particularlyon the east side, results in lower solute concentrations (minimum total dissolved solids 2730 mg/L) and totalradium (minimum 0.27 Bq/L) in oil-field water, and promotes biodegradation of dissolved organic carbon andhydrocarbon gases like propane. Acetate concentrations andδ13C of dissolved inorganic carbon indicate biogenicmethane production occurs in some shallow oil zones. Natural and human processes produce substantialvariability in the geochemistry of oil-field water that should be considered when evaluating mixing between oil-field waters and groundwater. The variability could result in uncertainty as to detecting the potential source andimpact of oil-field water on groundwater.

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Relative risk of groundwater-quality degradation near California (USA) oil fields estimated from 3H, 14C, and 4He

Applied Geochemistry (Elsevier) | June 5th, 2021

Summary

Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic

Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic data in the context of groundwater-age categories defined by tritium and carbon-14. In the Coastal basins, western San Joaquin Valley (SJV), and eastern SJV; 82, 76, and 0% of samples are premodern (pre-1953 recharge), respectively; and 3, 0, and 31% are modern (recharged during or after 1953), respectively. Carbon-14 and helium-4 data indicate most premodern samples are 1000 to 10,000 (33%) or >10,000 (50%) years old. Organic chemicals that could be associated with deeper hydrocarbon reservoirs (e.g. thermogenic gases and benzene) occur most frequently in premodern groundwater, suggesting premodern groundwater has a higher risk of degradation from upward migration of hydrocarbons than modern and mixed-age groundwater. Low sulfate concentrations in some premodern groundwater containing high thermogenic-methane concentrations (>28 mg/L) indicate methane attenuation associated with sulfate reduction can be limited in premodern groundwater. The more common occurrence of manufactured compounds, like tetrachloroethene, in modern and mixed-age groundwater than in premodern groundwater indicates modern and mixed-age groundwater has a higher risk of degradation from land-surface sources than premodern groundwater. Time-series data for chloride in groundwater affected by disposal of oil-field water in unlined ponds indicate some modern and mixed-age groundwater are susceptible to chemical migration within 2–3 km of surface sources. Timescales for diluting chloride concentrations in groundwater with fresh recharge once disposal ponds are decommissioned are shorter in mixed-age groundwater with large fractions of modern water (9–14 years in one example) than in mixed-age groundwater with large fractions of premodern water (no evidence of dilution after 12 years of monitoring in one example). The presence of predominantly premodern groundwater in the Coastal basins and western SJV indicates these areas have relatively high risk from upward migration of hydrocarbons, reduced methane attenuation capacity, and long dilution times, whereas predominantly modern-and mixed-age groundwater in the eastern SJV indicates this area has relatively high risk from chemical migration from land-surface sources and subsequent extensive spreading. Age-based characterizations of relative risk could inform the design of groundwater-monitoring programs near oil fields in terms of the spatial distribution of monitoring points relative to source areas and monitoring frequency and duration.

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Salinity of deep groundwater in California: Water quantity, quality, and protection

National Academy of Sciences (NAS) | July 12th, 2016

Summary

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and g

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California’s Central Valley, an important agricultural region with growing groundwater demands, fresh [<3,000 ppm total dissolved solids (TDS)] groundwater volume is almost tripled to 2,700 km3, most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km3 of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; <10,000 ppm TDS). Up to 19% and 35% of oil/gas activities have occurred directly in freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California’s Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond.

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