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Geology topics

Yousif K. Kharaka

Publications and source records attributed to Yousif K. Kharaka.

At least 19 recordsLinked to original sources
USGS2018

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

Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gas fields are commonly used to examine the source of the formation water and possible impacts on groundwater in areas of oil and gas development. Understanding the geochemical variability of oil-field water could help to evaluate its origin and delineate possible contamination of shallow aquifers in cases where oil-field water is released to the environment. Here we report geochemical and multiple isotope (H, C, O, Sr, Ra) data from 22 oil wells, three sources of produced water that are disposed of in injection wells, and two surface disposal ponds in four oil fields in the southern San Joaquin Valley, California (Fruitvale, Lost Hills, North and South Belridge). Correlations between Cl and δ 18 O, as well as other ions, and gradual increases in salinity with depth, indicate dilution of one or more saline 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 Na Cl composition, near-seawater Cl concentrations (median 20,000 mg/L), enriched δ 18 O H 2 O (median 3.4‰), high ammonium(up to 460 mg-N/L), and relatively high radium activity ( 226 Ra+ 228 Ra = 12.3 Bq/L). The deepest sample has low Na/Cl (0.74), high Ca/Mg (5.0), and low 87 Sr/ 86 Sr (0.7063), whereas the shallower samples have higher Na/Cl (0.86–1.2), Ca/Mg near 1, and higher 87 Sr/ 86 Sr (∼0.7083). The data are consistent with an original seawater source being modified by various depth and lithology dependent diagenetic processes. Dilution by meteoric water occurs naturally on the east side of the valley, and in association with water-injectionactivities on the west side. Meteoric-water flushing, particularly on the east side, results in lower solute concentrations (minimum total dissolved solids 2730 mg/L) and total radium (minimum 0.27 Bq/L) in oil-field water, and promotes biodegradation of dissolved organic carbon and hydrocarbon gases like propane. Acetate concentrations and δ 13 C of dissolved inorganic carbon indicate biogenic methane production occurs in some shallow oil zones. Natural and human processes produce substantial variability 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 and impact of oil-field water on groundwater.

California↗
USGS2017

Methane and benzene in drinking-water wells overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas

Water wells ( n = 116) overlying the Eagle Ford, Fayetteville, and Haynesville Shale hydrocarbon production areas were sampled for chemical, isotopic, and groundwater-age tracers to investigate the occurrence and sources of selected hydrocarbons in groundwater. Methane isotopes and hydrocarbon gas compositions indicate most of the methane in the wells was biogenic and produced by the CO 2 reduction pathway, not from thermogenic shale gas. Two samples contained methane from the fermentation pathway that could be associated with hydrocarbon degradation based on their co-occurrence with hydrocarbons such as ethylbenzene and butane. Benzene was detected at low concentrations (<0.15 μg/L), but relatively high frequencies (2.4–13.3% of samples), in the study areas. Eight of nine samples containing benzene had groundwater ages >2500 years, indicating the benzene was from subsurface sources such as natural hydrocarbon migration or leaking hydrocarbon wells. One sample contained benzene that could be from a surface release associated with hydrocarbon production activities based on its age (10 ± 2.4 years) and proximity to hydrocarbon wells. Groundwater travel times inferred from the age-data indicate decades or longer may be needed to fully assess the effects of potential subsurface and surface releases of hydrocarbons on the wells.

Environmental Science & Technology↗
USGS2017

Changes in the Chemistry of Groundwater Reacted with CO 2 : Comparison of Laboratory Results with the ZERT Field Pilot

As part of the ZERT program, sediments from two wells at the ZERT site, located in Bozeman, Montana, USA were reacted with a solution having the composition of local groundwater. A total of 50 water samples were collected from 7 containers placed for 15 days in a glove box with one atmosphere of CO 2 to investigate detailed changes in the concentrations of major, minor and trace inorganic compounds, and to compare these with changes observed in groundwater at the ZERT site following CO 2 injection. Laboratory results included rapid changes in pH (8.6 to 5.7), alkalinity (243 to 1295 mg/L as HCO 3 ), electrical conductance (539 to 1822 μS/cm), Ca (28 to 297 mg/L), Mg (18 to 63 mg/L), Fe (5 to 43 μg/L) and Mn (2 to 837 μg/L) following CO 2 injection. These chemical changes, which are in general agreement with those obtained from sampling the ZERT monitoring wells, could provide early detection of CO 2 leakage into shallow groundwater. Dissolution of calcite, some dolomite and minor Mn-oxides, and desorption/ion exchange are likely the main geochemical processes responsible for the observed changes.

Procedia Earth and Planetary Science↗
USGS2016

Comparison of geochemical data obtained using four brine sampling methods at the SECARB Phase III Anthropogenic Test CO2 injection site, Citronelle Oil Field, Alabama

The chemical composition of formation water and associated gases from the lower Cretaceous Paluxy Formation was determined using four different sampling methods at a characterization well in the Citronelle Oil Field, Alabama, as part of the Southeast Regional Carbon Sequestration Partnership (SECARB) Phase III Anthropogenic Test, which is an integrated carbon capture and storage project. In this study, formation water and gas samples were obtained from well D-9-8 #2 at Citronelle using gas lift, electric submersible pump, U-tube, and a downhole vacuum sampler (VS) and subjected to both field and laboratory analyses. Field chemical analyses included electrical conductivity, dissolved sulfide concentration, alkalinity, and pH; laboratory analyses included major, minor and trace elements, dissolved carbon, volatile fatty acids, free and dissolved gas species. The formation water obtained from this well is a Na&ndash;Ca&ndash;Cl-type brine with a salinity of about 200,000 mg/L total dissolved solids. Differences were evident between sampling methodologies, particularly in pH, Fe and alkalinity. There was little gas in samples, and gas composition results were strongly influenced by sampling methods. The results of the comparison demonstrate the difficulty and importance of preserving volatile analytes in samples, with the VS and U-tube system performing most favorably in this aspect.

International Journal of Coal Geology↗
USGS2015

Carbon isotope analysis of dissolved organic carbon in fresh and saline (NaCl) water via continuous flow cavity ring-down spectroscopy following wet chemical oxidation

This work examines the performance and limitations of a wet chemical oxidation carbon analyser interfaced with a cavity ring-down spectrometer (WCO-CRDS) in a continuous flow (CF) configuration for measuring &delta; 13 C of dissolved organic carbon ( &delta; 13 C-DOC) in natural water samples. Low-chloride matrix (<5 g Cl/L) DOC solutions were analysed with as little as 2.5 mg C/L in a 9 mL aliquot with a precision of 0.5 &permil;. In high-chloride matrix (10&ndash;100 g Cl/L) DOC solutions, bias towards lighter &delta; 13 C-DOC was observed because of incomplete oxidation despite using high-concentration oxidant, extended reaction time, or post-wet chemical oxidation gas-phase combustion. However, through a combination of dilution, chloride removal, and increasing the oxidant:sample ratio, high-salinity samples with sufficient DOC (>22.5 &micro;g C/aliquot) may be analysed. The WCO-CRDS approach requires more total carbon (&micro;g C/aliquot) than conventional CF-isotope ratio mass spectrometer, but is nonetheless applicable to a wide range of DOC concentration and water types, including brackish water, produced water, and basinal brines.

Isotopes in Environmental and Health Studies↗
USGS2013

Geochemical monitoring for potential environmental impacts of geologic sequestration of CO 2

Carbon dioxide sequestration is now considered an important component of the portfolio of options for reducing greenhouse gas emissions to stabilize their atmospheric levels at values that would limit global temperature increases to the target of 2 °C by the end of the century (Pacala and Socolow 2004; IPCC 2005, 2007; Benson and Cook 2005; Benson and Cole 2008; IEA 2012; Romanak et al. 2013). Increased anthropogenic emissions of CO2 have raised its atmospheric concentrations from about 280 ppmv during pre-industrial times to ~400 ppmv today, and based on several defined scenarios, CO2 concentrations are projected to increase to values as high as 1100 ppmv by 2100 (White et al. 2003; IPCC 2005, 2007; EIA 2012; Global CCS Institute 2012). An atmospheric CO2 concentration of 450 ppmv is generally the accepted level that is needed to limit global temperature increases to the target of 2 °C by the end of the century. This temperature limit likely would moderate the adverse effects related to climate change that could include sea-level rise from the melting of alpine glaciers and continental ice sheets and from the ocean warming; increased frequency and intensity of wildfires, floods, droughts, and tropical storms; and changes in the amount, timing, and distribution of rain, snow, and runoff (IPCC 2007; Sundquist et al. 2009; IEA 2012). Rising atmospheric CO2 concentrations are also increasing the amount of CO2 dissolved in ocean water lowering its pH from 8.1 to 8.0, with potentially disruptive effects on coral reefs, plankton and marine ecosystems (Adams and Caldeira 2008; Schrag 2009; Sundquist et al. 2009). Sedimentary basins in general and deep saline aquifers in particular are being investigated as possible repositories for the large volumes of anthropogenic CO2 that must be sequestered to mitigate global warming and related climate changes (Hitchon 1996; Benson and Cole 2008; Verma and Warwick 2011).

Reviews in Mineralogy and Geochemistry↗
USGS2013

The energy-water nexus: Potential groundwater-quality degradation associated with production of shale gas

Oil and natural gas have been the main sources of primary energy in the USA, providing 63% of the total energy consumption in 2011. Petroleum production, drilling operations, and improperly sealed abandoned wells have caused significant local groundwater contamination in many states, including at the USGS OSPER sites in Oklahoma. The potential for groundwater contamination is higher when producing natural gas and oil from unconventional sources of energy, including shale and tight sandstones. These reservoirs require horizontally-completed wells and massive hydraulic fracturing that injects large volumes (up to 50,000 m3/well) of high-pressured water with added proppant, and toxic organic and inorganic chemicals. Recent results show that flow back and produced waters from Haynesville (Texas) and Marcellus (Pennsylvania) Shale have high salinities (&ge;200,000 mg/L TDS) and high NORMs (up to 10,000 picocuries/L) concentrations. A major research effort is needed worldwide to minimize all potential environmental impacts, especially groundwater contamination and induced seismicity, when producing these extremely important new sources of energy.

Procedia Earth and Planetary Science↗
USGS2012

CO 2 –rock–brine interactions in Lower Tuscaloosa Formation at Cranfield CO 2 sequestration site, Mississippi, U.S.A.

A highly integrated geochemical program was conducted at the Cranfield CO 2 -enhanced oil recovery (EOR) and sequestration site, Mississippi, U.S.A.. The program included extensive field geochemical monitoring, a detailed petrographic study, and an autoclave experiment under in situ reservoir conditions. Results show that mineral reactions in the Lower Tuscaloosa reservoir were minor during CO 2 injection. Brine chemistry remained largely unchanged, which contrasts with significant changes observed in other field tests. Field fluid sampling and laboratory experiments show consistently slow reactions. Carbon isotopic composition and CO 2 content in the gas phase reveal simple two-end-member mixing between injected and original formation gas. We conclude that the reservoir rock, which is composed mainly of minerals with low reactivity (average quartz 79.4%, chlorite 11.8%, kaolinite 3.1%, illite 1.3%, concretionary calcite and dolomite 1.5%, and feldspar 0.2%), is relatively unreactive to CO 2 . The significance of low reactivity is both positive, in that the reservoir is not impacted, and negative, in that mineral trapping is insignificant.

Mississippi↗
USGS2012

Geochemical modeling of changes in shallow groundwater chemistry observed during the MSU-ZERT CO2 injection experiment

A field experiment involving the release of carbon dioxide (CO 2 ) into a shallow aquifer was conducted near Bozeman, Montana, during the summer of 2008, to investigate the potential groundwater quality impacts in the case of leakage of CO 2 from deep geological storage. As an essential part of the Montana State University Zero Emission Research and Technology (MSU-ZERT) field program, food-grade CO 2 was injected over a 30 day period into a horizontal perforated pipe a few feet below the water table of a shallow aquifer. The impact of elevated CO 2 concentrations on groundwater quality was investigated by analyzing water samples taken before, during, and following CO 2 injection, from observation wells located in the vicinity of the injection pipe, and from two distant monitoring wells. Field measurements and laboratory analyses showed rapid and systematic changes in pH, alkalinity, and conductance, as well as increases in the aqueous concentrations of naturally occurring major and trace element species. The geochemical data were evaluated using principal component analysis (PCA) to (1) understand potential correlations between aqueous species, and (2) to identify minerals controlling the chemical composition of the groundwater prior to CO 2 injection. These evaluations were used to assess possible geochemical processes responsible for the observed increases in the concentrations of dissolved constituents, and to simulate these processes using a multicomponent reaction path model. Reasonable agreement between observed and modeled data suggests that (1) calcite dissolution was the primary pH buffer, yielding increased Ca +2 concentrations in the groundwater, (2) increases in the concentrations of most major and trace metal cations except Fe could be a result of Ca +2 -driven exchange reactions, (3) the release of anions from adsorption sites due to competitive adsorption of carbonate could explain the observed trends of most anions, and (4) the dissolution of reactive Fe minerals (presumed ferrihydrite and fougerite, from thermodynamic analyses) could explain increases in total Fe concentration. Highlights ► Because the possibility of CO 2 leakage cannot be completely ruled out, the potential impact of CO 2 intrusion on the quality of fresh water aquifers overlying CO 2 storage sites needs to be investigated. ► Geochemical data from a field experiment involving the release of carbon dioxide (CO 2 ) into a shallow aquifer were evaluated. ► Geochemical model used to assess possible geochemical processes responsible for the observed increases in the concentrations of dissolved constituents. ► Reasonable agreement between observed and modeled data suggests that increases in the concentrations of most major and trace metal cations except Fe could be a result of Ca +2 -driven exchange reactions and the release of anions from adsorption sites due to competitive adsorption of carbonate could explain the observed trends of most anions.

Montana↗
USGS2011

Transient changes in shallow groundwater chemistry during the MSU ZERT CO2 injection experiment

Food-grade CO 2 was injected into a shallow aquifer through a perforated pipe placed horizontally 1–2 m below the water table at the Montana State University Zero Emission Research and Technology (MSU-ZERT) field site at Bozeman, Montana. The possible impact of elevated CO 2 levels on groundwater quality was investigated by analyzing 80 water samples taken before, during, and following CO 2 injection. Field determinations and laboratory analyses showed rapid and systematic changes in pH, alkalinity, and conductance, as well as increases in the aqueous concentrations of trace element species. The geochemical data were first evaluated using principal component analysis (PCA) in order to identify correlations between aqueous species. The PCA findings were then used in formulating a geochemical model to simulate the processes likely to be responsible for the observed increases in the concentrations of dissolved constituents. Modeling was conducted taking into account aqueous and surface complexation, cation exchange, and mineral precipitation and dissolution. Reasonable matches between measured data and model results suggest that: (1) CO 2 dissolution in the groundwater causes calcite to dissolve. (2) Observed increases in the concentration of dissolved trace metals result likely from Ca +2 -driven ion exchange with clays (smectites) and sorption/desorption reactions likely involving Fe (hydr)oxides. (3) Bicarbonate from CO 2 dissolution appears to compete for sorption with anionic species such as HAsO 4 −2 , potentially increasing dissolved As levels in groundwater.

Conference Paper↗
USGS2010

Extraction of organic compounds from organic-rich rocks during geologic CO2 sequestration at supercritical conditions

At reservoir conditionscarbon dioxide is a supercritical fluid capable of extraction of naturallyoccurring neutral compounds from formation materials, including carboxylicacids at low pH. We performed a series of experiments designed to quantify theextractable carboxylic acid and neutral aromatic yield from coal of the WilcoxGroup in Louisiana. We determined concentrations of organic species in both the aqueous phase and carbon dioxide phases during batch reactions of rock with the two fluid phases. The concentration patterns observed following preliminary experiments indicate that high concentrations of aromatic acids are observed preferentially in the supercritical phase whereas aliphatic short-chain and dicarboxylic acids are preferentially found in the aqueousphase. We conclude that organic-rich rocks such as coal will be sources of organic acids following geologic CO 2 sequestration. Organic compound liberation from rocks has important implications for the subsurface microbial community and weathering rates of seal and reservoir silicates.

Conference Paper↗
USGS2009

A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models

A controlled field pilot has been developed in Bozeman, Montana, USA, to study near surface CO2 transport and detection technologies. A slotted horizontal well divided into six zones was installed in the shallow subsurface. The scale and CO2 release rates were chosen to be relevant to developing monitoring strategies for geological carbon storage. The field site was characterized before injection, and CO2 transport and concentrations in saturated soil and the vadose zone were modeled. Controlled releases of CO2 from the horizontal well were performed in the summers of 2007 and 2008, and collaborators from six national labs, three universities, and the U.S. Geological Survey investigated movement of CO2 through the soil, water, plants, and air with a wide range of near surface detection techniques. An overview of these results will be presented.

Montana↗
USGS2009

Changes in the chemistry of shallow groundwater related to the 2008 injection of CO2 at the ZERT field site, Bozeman, Montana

Approximately 300 kg/day of food-grade CO 2 was injected through a perforated pipe placed horizontally 2–2.3 m deep during July 9–August 7, 2008 at the MSU-ZERT field test to evaluate atmospheric and near-surface monitoring and detection techniques applicable to the subsurface storage and potential leakage of CO 2 . As part of this multidisciplinary research project, 80 samples of water were collected from 10 shallow monitoring wells (1.5 or 3.0 m deep) installed 1–6 m from the injection pipe, at the southwestern end of the slotted section (zone VI), and from two distant monitoring wells. The samples were collected before, during, and following CO 2 injection. The main objective of study was to investigate changes in the concentrations of major, minor, and trace inorganic and organic compounds during and following CO 2 injection. The ultimate goals were (1) to better understand the potential of groundwater quality impacts related to CO 2 leakage from deep storage operations, (2) to develop geochemical tools that could provide early detection of CO 2 intrusion into underground sources of drinking water (USDW), and (3) to test the predictive capabilities of geochemical codes against field data. Field determinations showed rapid and systematic changes in pH (7.0–5.6), alkalinity (400–1,330 mg/l as HCO 3 ), and electrical conductance (600–1,800 μS/cm) following CO 2 injection in samples collected from the 1.5 m-deep wells. Laboratory results show major increases in the concentrations of Ca (90–240 mg/l), Mg (25–70 mg/l), Fe (5–1,200 ppb), and Mn (5–1,400 ppb) following CO 2 injection. These chemical changes could provide early detection of CO 2 leakage into shallow groundwater from deep storage operations. Dissolution of observed carbonate minerals and desorption-ion exchange resulting from lowered pH values following CO 2 injection are the likely geochemical processes responsible for the observed increases in the concentrations of solutes; concentrations generally decreased temporarily following four significant precipitation events. The DOC values obtained are 5 ± 2 mg/l, and the variations do not correlate with CO 2 injection. CO 2 injection, however, is responsible for detection of BTEX (e.g. benzene, 0–0.8 ppb), mobilization of metals, the lowered pH values, and increases in the concentrations of other solutes in groundwater. The trace metal and BTEX concentrations are all significantly below the maximum contaminant levels (MCLs). Sequential leaching of core samples is being carried out to investigate the source of metals and other solutes.

Montana↗
USGS2009

Potential environmental issues of CO 2 storage in deep saline aquifers: Geochemical results from the Frio-I Brine Pilot test, Texas, USA

Sedimentary basins in general, and deep saline aquifers in particular, are being investigated as possible repositories for large volumes of anthropogenic CO 2 that must be sequestered to mitigate global warming and related climate changes. To investigate the potential for the long-term storage of CO 2 in such aquifers, 1600 t of CO 2 were injected at 1500 m depth into a 24-m-thick "C" sandstone unit of the Frio Formation, a regional aquifer in the US Gulf Coast. Fluid samples obtained before CO 2 injection from the injection well and an observation well 30 m updip showed a Na–Ca–Cl type brine with ∼93,000 mg/L TDS at saturation with CH 4 at reservoir conditions; gas analyses showed that CH 4 comprised ∼95% of dissolved gas, but CO 2 was low at 0.3%. Following CO 2 breakthrough, 51 h after injection, samples showed sharp drops in pH (6.5–5.7), pronounced increases in alkalinity (100–3000 mg/L as HCO 3 ) and in Fe (30–1100 mg/L), a slug of very high DOC values, and significant shifts in the isotopic compositions of H 2 O, DIC, and CH 4 . These data, coupled with geochemical modeling, indicate corrosion of pipe and well casing as well as rapid dissolution of minerals, especially calcite and iron oxyhydroxides, both caused by lowered pH (initially ∼3.0 at subsurface conditions) of the brine in contact with supercritical CO 2 . These geochemical parameters, together with perfluorocarbon tracer gases (PFTs), were used to monitor migration of the injected CO 2 into the overlying Frio “B”, composed of a 4-m-thick sandstone and separated from the “C” by ∼15 m of shale and siltstone beds. Results obtained from the Frio “B” 6 months after injection gave chemical and isotopic markers that show significant CO 2 (2.9% compared with 0.3% CO 2 in dissolved gas) migration into the “B” sandstone. Results of samples collected 15 months after injection, however, are ambiguous, and can be interpreted to show no additional injected CO 2 in the “B” sandstone. The presence of injected CO 2 may indicate migration from “C” to “B” through the intervening beds or, more likely, a short-term leakage through the remedial cement around the casing of a 50-year old well. Results obtained to date from four shallow monitoring groundwater wells show no brine or CO 2 leakage through the Anahuac Formation, the regional cap rock.

Texas↗
USGS2009

Development of a probabilistic assessment methodology for evaluation of carbon dioxide storage

This report describes a probabilistic assessment methodology developed by the U.S. Geological Survey (USGS) for evaluation of the resource potential for storage of carbon dioxide (CO 2 ) in the subsurface of the United States as authorized by the Energy Independence and Security Act (Public Law 110-140, 2007). The methodology is based on USGS assessment methodologies for oil and gas resources created and refined over the last 30 years. The resource that is evaluated is the volume of pore space in the subsurface in the depth range of 3,000 to 13,000 feet that can be described within a geologically defined storage assessment unit consisting of a storage formation and an enclosing seal formation. Storage assessment units are divided into physical traps (PTs), which in most cases are oil and gas reservoirs, and the surrounding saline formation (SF), which encompasses the remainder of the storage formation. The storage resource is determined separately for these two types of storage. Monte Carlo simulation methods are used to calculate a distribution of the potential storage size for individual PTs and the SF. To estimate the aggregate storage resource of all PTs, a second Monte Carlo simulation step is used to sample the size and number of PTs. The probability of successful storage for individual PTs or the entire SF, defined in this methodology by the likelihood that the amount of CO 2 stored will be greater than a prescribed minimum, is based on an estimate of the probability of containment using present-day geologic knowledge. The report concludes with a brief discussion of needed research data that could be used to refine assessment methodologies for CO 2 sequestration.

Open-File Report↗
USGS2007

Preface

Energy is the essential commodity that powers the expanding global economy. Starting in the 1950s, oil and natural gas became the main sources of primary energy for the rapidly increasing world population ( Edwards, 1997 ). In 2003, petroleum was the source for 62.1% of global energy, and projections by energy information administration (EIA) indicate that oil and gas will continue their dominance, supplying 59.5% of global energy in 2030 ( EIA, 2007 ). Unfortunately petroleum and coal consumption carry major detrimental environmental impacts that may be regional or global in scale, including air pollution, global climate change and oil spills. This special volume of Applied Geochemistry, devoted to “Environmental Issues Related to Oil and Gas Exploration and Production”, does not address these major impacts directly because air pollution and global climate change are issues related primarily to the burning of petroleum and coal, and major oil spills generally occur during ocean transport, such as the Exxon Valdez 1989 spill of 42,000 m 3 (260,000 bbl) oil into Prince William Sound, Alaska.

Applied Geochemistry↗