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Yousif K. Kharaka

Publications and source records attributed to Yousif K. Kharaka.

At least 37 records · Page 2Linked to original sources
USGS2007

Hydrology and subsurface transport of oil-field brine at the U.S. Geological Survey OSPER site "A", Osage County, Oklahoma

Spillage and improper disposal of saline produced water from oil wells has caused environmental damage at thousands of sites in the United States. In order to improve understanding of the fate and transport of contaminants at these sites, the U.S. Geological Survey carried out multidisciplinary investigations at two oil production sites near Skiatook Lake, Oklahoma. As a part of this effort, the hydrology and subsurface transport of brine at OSPER site “A”, a tank battery and pit complex that was abandoned in 1973, was investigated. Based on data from 41 new boreholes that were cored and completed with monitoring wells, a large (∼200 m × 200 m × 20 m) plume of saline ground water was mapped. The main dissolved species are Na and Cl, with TDS in the plume ranging as high as 30,000 mg/L. Analysis of the high barometric efficiency of the wells indicated a confined aquifer response. Well-slug tests indicated the hydraulic conductivity is low (0.3–7.0 cm/day). Simplified flow and transport modeling supports the following conceptual model: (1) prior to the produced water releases, recharge was generally low (∼1 cm/a); (2) in ∼60 a of oil production enough saline produced water in pits leaked into the subsurface to create the plume; (3) following abandonment of the site in 1973 and filling of Skiatook Reservoir in the mid-1980s, recharge and lateral flow of water through the plume returned to low values; (4) as a result, spreading of the brine plume caused by mixing with fresh ground water recharge, as well as natural attenuation, are very slow.

Oklahoma↗
USGS2007

Fate and groundwater impacts of produced water releases at OSPER "B" site, Osage County, Oklahoma

For the last 5 a, the authors have been investigating the transport, fate, natural attenuation and ecosystem impacts of inorganic and organic compounds in releases of produced water and associated hydrocarbons at the Osage-Skiatook Petroleum Environmental Research (OSPER) “A” and “B” sites, located in NE Oklahoma. Approximately 1.0 ha of land at OSPER “B”, located within the active Branstetter lease, is visibly affected by salt scarring, tree kills, soil salinization, and brine and petroleum contamination. Site “B” includes an active production tank battery and adjacent large brine pit, two injection well sites, one with an adjacent small pit, and an abandoned brine pit and tank battery site. Oil production in this lease started in 1938, and currently there are 10 wells that produce 0.2–0.5 m 3 /d (1–3 bbl/d) oil, and 8–16 m 3 /d (50–100 bbl/d) brine. Geochemical data from nearby oil wells show that the produced water source is a Na–Ca–Cl brine (∼150,000 mg/L TDS), with high Mg, but low SO 4 and dissolved organic concentrations. Groundwater impacts are being investigated by detailed chemical analyses of water from repeated sampling of 41 boreholes, 1–71 m deep. The most important results at OSPER “B” are: (1) significant amounts of produced water from the two active brine pits percolate into the surficial rocks and flow towards the adjacent Skiatook reservoir, but only minor amounts of liquid petroleum leave the brine pits; (2) produced-water brine and minor dissolved organics have penetrated the thick (3–7 m) shale and siltstone units resulting in the formation of three interconnected plumes of high-salinity water (5000–30,000 mg/L TDS) that extend towards the Skiatook reservoir from the two active and one abandoned brine pits; and (3) groundwater from the deep section of only one well, BR-01 located 330 m upslope and west of the site, appear not to be impacted by petroleum operations.

Oklahoma↗
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↗
USGS2007

Geochemical data from produced water contamination investigations: Osage-Skiatook Petroleum Environmental Research (OSPER) sites, Osage County, Oklahoma

We report chemical and isotopic analyses of 345 water samples collected from the Osage-Skiatook Petroleum Environmental Research (OSPER) project. Water samples were collected as part of an ongoing multi-year USGS investigation to study the transport, fate, natural attenuation, and ecosystem impacts of inorganic salts and organic compounds present in produced water releases at two oil and gas production sites from an aging petroleum field located in Osage County, in northeast Oklahoma. The water samples were collected primarily from monitoring wells and surface waters at the two research sites, OSPER A (legacy site) and OSPER B (active site), during the period March, 2001 to February, 2005. The data include produced water samples taken from seven active oil wells, one coal-bed methane well and two domestic groundwater wells in the vicinity of the OSPER sites.

Oklahoma↗
USGS2006

Gas-water-rock interactions in Frio Formation following CO 2 injection: Implications for the storage of greenhouse gases in sedimentary basins

To investigate the potential for the geologic storage of CO 2 in saline sedimentary aquifers, 1600 t of CO 2 were injected at 1500 m depth into a 24-m-thick sandstone section of the Frio Formation, a regional brine and oil reservoir in the U.S. Gulf Coast. Fluid samples obtained from the injection and observation wells before CO 2 injection showed a Na-Ca-Cl–type brine with 93,000 mg/L total dissolved solids (TDS) at near saturation with CH 4 at reservoir conditions. Following CO 2 breakthrough, samples showed sharp drops in pH (6.5–5.7), pronounced increases in alkalinity (100–3000 mg/L as HCO 3 ) and Fe (30–1100 mg/L), and significant shifts in the isotopic compositions of H 2 O, dissolved inorganic carbon (DIC), and CH 4 . Geochemical modeling indicates that brine pH would have dropped lower but for the buffering by dissolution of carbonate and iron oxyhydroxides. This rapid dissolution of carbonate and other minerals could ultimately create pathways in the rock seals or well cements for CO 2 and brine leakage. Dissolution of minerals, especially iron oxyhydroxides, could mobilize toxic trace metals and, where residual oil or suitable organics are present, the injected CO 2 could also mobilize toxic organic compounds. Environmental impacts could be major if large brine volumes with mobilized toxic metals and organics migrated into potable groundwater. The δ 18 O values for brine and CO 2 samples indicate that supercritical CO 2 comprises ∼50% of pore-fluid volume ∼6 mo after the end of injection. Postinjection sampling, coupled with geochemical modeling, indicates that the brine gradually will return to its preinjection composition.

Geology↗
USGS2006

Measuring permanence of CO 2 storage in saline formations: The Frio experiment

If CO 2 released from fossil fuel during energy production is returned to the subsurface, will it be retained for periods of time significant enough to benefit the atmosphere? Can trapping be assured in saline formations where there is no history of hydrocarbon accumulation? The Frio experiment in Texas was undertaken to provide answers to these questions. One thousand six hundred metric tons of CO 2 were injected into the Frio Formation, which underlies large areas of the United States Gulf Coast. Reservoir characterization and numerical modeling were used to design the experiment, as well as to interpret the results through history matching. Closely spaced measurements in space and time were collected to observe the evolution of immiscible and dissolved CO 2 during and after injection. The high-permeability, steeply dipping sandstone allowed updip flow of supercritical CO 2 as a result of the density contrast with formation brine and absence of a local structural trap. The front of the CO 2 plume moved more quickly than had been modeled. By the end of the 10-day injection, however, the plume geometry in the plane of the observation and injection wells had thickened to a distribution similar to the modeled distribution. As expected, CO 2 dissolved rapidly into brine, causing pH to fall and calcite and metals to be dissolved. Postinjection measurements, including time-lapse vertical seismic profiling transects along selected azimuths, cross-well seismic topography, and saturation logs, show that CO 2 migration under gravity slowed greatly 2 months after injection, matching model predictions that significant CO 2 is trapped as relative permeability decreases.

Environmental Geosciences↗
USGS2005

The U-tube: A novel system for acquiring borehole fluid samples from a deep geologic CO2 sequestration experiment

A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO 2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase fluid (supercritical CO 2 and brine) fluid from 1.5 km depth. The data sets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydrogeochemical issues affecting CO 2 sequestration in brine-filled formations. While the basic premise underlying the U-tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO 2 . A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO 2 . The U-tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO 2 plume, and on-site analysis revealed rapid changes in geochemical conditions.

Journal of Geophysical Research Solid Earth↗
USGS2005

Environmental issues of petroleum exploration and production: Introduction

Energy is the lifeblood of our planet Earth, an essential commod- ity that powers the expanding global economy. Starting in the 1950s, oil and natural gas became the main sources of primary energy for the increasing world population, and this dominance is expected to continue for several more decades (Edwards, 1997; Energy Information Administration (EIA), 2004). In the United States, petroleum production started in 1859 when Drake's well was drilled near Titusville, Pennsylvania, and oil and natural gas currently supply approximately 63% of the energy consumption; forecasts indicate that by 2025, their use will increase by about 40% to 28.3 million bbl/day and to 31.4 tcf/yr (EIA, 2004). The clear benefits of petroleum consumption, however, can carry major environmental impacts that may be regional or global in scale, in- cluding air pollution, global climate change, and oil spills. This vol- ume of Environmental Geosciences, covering environmental impacts of petroleum exploration and production, does not address these major impacts directly because air pollution and global warming are issues related primarily to petroleum and coal uses, and major oil spills are generally attributed to marine petroleum transportation, such as the Exxon Valdez's 1989 spill of 260,000 bbl of oil into Prince William Sound, Alaska. Exploration for and production of petroleum, however, have caused local detrimental impacts to soils, surface and groundwa- ters, and ecosystems in the 36 producing states in the United States (Richter and Kreitler, 1993; Kharaka and Hanor, 2003). These im- pacts arose primarily from the improper disposal of some of the large volumes (presently estimated at 20 billion bbl/yr total pro- duced) of saline water produced with oil and gas, from accidental hydrocarbon and produced-water releases, and from abandoned oil wells that were orphaned or not correctly plugged (Kharaka et al., 1995; Veil et al., 2004). Impacts and ground-surface disturbances, in the order of several acres per well, can also arise from related activities such as site clearance, construction of roads, tank bat- teries, brine pits and pipelines, and other land modifications nec- essary for the drilling of exploration and production wells and construction of production facilities. The cumulative impacts from these operations are high, because a total of about 3.5 million oil.

Environmental Geosciences↗
USGS2004

A compilation of rate parameters of water-mineral interaction kinetics for application to geochemical modeling

Geochemical reaction path modeling is useful for rapidly assessing the extent of water-aqueous-gas interactions both in natural systems and in industrial processes. Modeling of some systems, such as those at low temperature with relatively high hydrologic flow rates, or those perturbed by the subsurface injection of industrial waste such as CO2 or H2S, must account for the relatively slow kinetics of mineral-gas-water interactions. We have therefore compiled parameters conforming to a general Arrhenius-type rate equation, for over 70 minerals, including phases from all the major classes of silicates, most carbonates, and many other non-silicates. The compiled dissolution rate constants range from -0.21 log moles m-2 s-1 for halite, to -17.44 log moles m-2 s-1 for kyanite, for conditions far from equilibrium, at 25 ?C, and pH near neutral. These data have been added to a computer code that simulates an infinitely well-stirred batch reactor, allowing computation of mass transfer as a function of time. Actual equilibration rates are expected to be much slower than those predicted by the selected computer code, primarily because actual geochemical processes commonly involve flow through porous or fractured media, wherein the development of concentration gradients in the aqueous phase near mineral surfaces, which results in decreased absolute chemical affinity and slower reaction rates. Further differences between observed and computed reaction rates may occur because of variables beyond the scope of most geochemical simulators, such as variation in grain size, aquifer heterogeneity, preferred fluid flow paths, primary and secondary mineral coatings, and secondary minerals that may lead to decreased porosity and clogged pore throats.

Open-File Report↗
USGS2004

Organic and inorganic species in produced water: Implications for water reuse

Currently 20-30 billion barrels of formation water are co-produced annually in the USA with conventional oil and natural gas. The large database on the geochemistry of this produced water shows salinities that vary widely from ~5,000 to >350,000 mg/L TDS. Chloride, Na and Ca are generally the dominant ions, and concentrations of Fe, Mn, B, NH3 and dissolved organics, including, BTEX, phenols and poly aromatic hydrocarbons (PAHs) may be relatively high. Hazardous concentrations of NORMs, including Ra-226 and Rn-222 have been reported in produced water from several states. Coal-bed methane (CBM) wells currently produce close to a billion barrels of water and deliver ~8% of total natural gas. The salinity of this produced water generally is lower than that of water from petroleum wells; salinity commonly is 1,000-20,000 mg/L, but ranges to150,000 mg/L TDS. Most CBM wells produce Na-HCO3-Cl type water that is low in trace metals and has no reported NORMs. This water commonly has no oil and grease and has relatively low DOC, but its organic composition has not been characterized in detail. The water is disposed of by injection into saline aquifers, through evaporation and/or percolation in disposal pits, road spreading, and surface discharge. Water that has an acceptable salinity and sodium absorption ratio (SAR) is considered acceptable for surface discharge and for injection into freshwater aquifers. As an alternative to costly disposal, low salinity produced water is being considered for reclamation, especially in the arid western USA. The cost of reclaiming this water to meet irrigation, industrial and drinking water standards was evaluated in a 10 gpm pilot field study at Placerita oil field, California. This produced water had a low salinity of ~8,000 mg/L, but high concentration of Si and organics. Removal of B, Si, NH3 and especially organics from this water proved difficult, and the estimated treatment cost was high at $0.08-$0.39/bbl for water treated for industrial and municipal uses.

Conference Paper↗
USGS2003

Environmental impacts of petroleum production--Initial results from the Osage-Skiatook Petroleum Environmental Research Sites, Osage County, Oklahoma

Exploration for and production of petroleum have caused major detrimental impacts to soils, surface and ground waters, and the local ecosystems in the United States. These impacts arise primarily from the improper disposal of large volumes of saline water produced with oil and gas, from accidental hydrocarbon and produced water releases, and from abandoned oil wells that were not correctly sealed. It is important to understand the long-term and short-term effects of produced water and hydrocarbon releases from these sites in order to develop risk-based remediation plans. Remediation is particularly needed in aging and depleted fields where land use is changing from petroleum production to residential, agricultural or recreational uses. About 20 scientists from the USGS and other governmental agencies and academia are involved in a multidisciplinary investigation to study the transport, fate, and natural attenuation of inorganic salts, trace metals, organic compounds and radionuclides present in produced water, and their impacts at the Osage-Skiatook Petroleum Environmental Research (OSPER) "A" and "B" sites, located on the Osage Reservation in Osage County, Oklahoma. Stakeholders in the project include the Osage Nation, which holds the mineral rights, the Bureau of Indian Affairs with trust responsibility, and the Army Corps of Engineers, which owns the surface rights at these sites and manages adjacent Skiatook Lake. The 4250-hectare Skiatook Lake provides drinking water to local Tulsa suburban communities and a rural water district, and offers recreational fishing and boating opportunities to tens of thousands of visitors each year. Approximately 1.5 and 1.0 hectare of land at the OSPER "A" (depleted Lester lease) and "B" (active Branstetter lease) sites, respectively, are affected by salt scarring, tree kills, soil salinization and brine and petroleum contamination due to the leakage of produced water and associated hydrocarbons from brine pits and accidental releases from active and inactive pipes and tank batteries. The leases are typical of many depleted and aging petroleum fields in Osage County, which ranks among the top oil and gas producing counties in Oklahoma with about 39,000 wells. Oil and gas production has occurred in Osage county for over one hundred years, but current production is mainly from stripper wells (averaging ~2.8 bbl/d oil and >30 bbl/d brine) that are shallow, mostly 300-700 m in depth, and produce from several sandstones of Pennsylvanian age. Results to date show that the produced water source is a Na-Ca-Cl brine (~150,000 mg/L total dissolved solids), with relatively high concentrations of Mg, Sr, and NH4, but low SO4 and H2S. With the exception of Fe and Mn, the concentrations of trace metals are low. Results also show that some and, eventually, the bulk, of inorganic salts and some dissolved organic species in the released brine from both sites will reach Skiatook Lake. Results at the "A" site show that the salts have essentially been removed from the sandy soil which formed in a surficial layer of eolian sand, but degraded and weathered oil persists on the surface of old oil and brine pits, close to sites of old tanks, on old channels that carried oil from tanks to the oil pits and other impacted areas. Results also show a plume of high salinity water (5,000-30,600 mg/L TDS) is present at intermediate depths that extend from below the old oil and brine pits to Skiatook Lake. No liquid petroleum was found in the contaminated groundwater, but soluble petroleum byproducts, including organic acid anions and other volatile organic compounds (VOCs) are present. Results to date clearly show that significant amounts of salts from produced-water releases and petroleum hydrocarbons still remain in the soils and rocks of the impacted area after more than 60 years of natural attenuation. At the "B" site significant amounts of produced water from the two active brine pits percolate into the surficial rocks and flow towards the Skiatook Reservoir; but only minor amounts of liquid petroleum leave the brine pits and reach the Skiatook Reservoir. At both sites, results show that the chemical composition of released brines is modified further by sorption, mineral precipitation/dissolution, transpiration, volatilization and bacterially mediated oxidation/reduction reactions.

Oklahoma↗
USGS2002

Chemical evolution of the Salton Sea, California: Nutrient and selenium dynamics

The Salton Sea is a 1000-km 2 terminal lake located in the desert area of southeastern California. This saline (∼44 000 mg l −1 dissolved solids) lake started as fresh water in 1905–07 by accidental flooding of the Colorado River, and it is maintained by agricultural runoff of irrigation water diverted from the Colorado River. The Salton Sea and surrounding wetlands have recently acquired substantial ecological importance because of the death of large numbers of birds and fish, and the establishment of a program to restore the health of the Sea. In this report, we present new data on the salinity and concentration of selected chemicals in the Salton Sea water, porewater and sediments, emphasizing the constituents of concern: nutrients (N and P), Se and salinity. Chemical profiles from a Salton Sea core estimated to have a sedimentation rate of 2.3 mm yr −1 show increasing concentrations of OC, N, and P in younger sediment that are believed to reflect increasing eutrophication of the lake. Porewater profiles from two locations in the Sea show that diffusion from bottom sediment is only a minor source of nutrients to the overlying water as compared to irrigation water inputs. Although loss of N and Se by microbial-mediated volatilization is possible, comparison of selected element concentrations in river inputs and water and sediments from the Salton Sea indicates that most of the N (from fertilizer) and virtually all of the Se (delivered in irrigation water from the Colorado River) discharged to the Sea still reside within its bottom sediment. Laboratory simulation on mixtures of sediment and water from the Salton Sea suggest that sediment is a potential source of N and Se to the water column under aerobic conditions. Hence, it is important that any engineered changes made to the Salton Sea for remediation or for transfer of water out of the basin do not result in remobilization of nutrients and Se from the bottom sediment into the overlying water.

California↗
USGS2002

Environmental impacts of petroleum production: Fate of inorganic and organic chemicals in produced water from the Osage-Skiatook Petroleum Environmental Research sites, Osage County, Oklahoma

About 15 scientists from the U. S. Geological Survey, other Federal agencies and academia are involved in a multidisciplinary investigation to study the transport, fate, and natural attenuation of inorganic salts, trace metals, radionuclides and organic compounds present in produced water, and their impacts on soil, surface and ground water and the local ecosystem at the Osage-Skiatook Petroleum Environmental Research (OSPER) A and B sites, located in Osage County, OK. The Branstetter lease, OSPER B site, is typical of many aging petroleum fields in Osage County, which ranks among the top oil and gas producing counties in Oklahoma with close to 40,000 wells. Current production in Osage County is mainly from stripper wells (averaging ~2.8 bbls/d oil and >30 bbls/d brine) that are shallow, mostly 300-700 m in depth, and produce from several sandstones of Pennsylvanian age. About one hectare of land at the OSPER B site is affected by salt scarring, soil salinization and brine and petroleum contamination due to the leakage of produced water and associated hydrocarbons from two brine pits and due to accidental releases from active tank batteries. Eventually, the bulk of inorganic salts and some dissolved organic species in the released brine reach, directly or via the two local streams, the adjacent Skiatook Lake, a 4250-hectare reservoir that provides drinking water to the local communities and is a major recreational fishery. About 40 water samples were obtained from several oil wells at the B site and adjoining areas, the two brine pits, several brine pools and seeps in the impacted area, local streams, Skiatook Lake, and from about 20 boreholes (1-71 m deep), recently drilled and completed with slotted PVC tubing. Water level monitoring and additional sampling is continuing. Results to date show that the produced water is a high-salinity (~150,000 mg/L total dissolved solids) Na-Ca-Cl brine, with relatively high concentrations of Sr, Mg and NH4, but low amounts of SO4 and H2S. With the exception of Fe and Mn, the concentrations of trace metals are low, and the values of dissolved organics are relatively low. As the brine flows from the brine pits through the shallow eolian sand, colluvial and alluvial deposits to the streams and Skiatook Lake, it is diluted by infiltrating water from precipitation. Its chemical composition is modified by sorption, mineral precipitation/dissolution, transpiration, volatilization and oxidation/reduction reactions. Bacteria likely play an important role in many of these reactions.

Oklahoma↗
USGS2002

Hydrologic controls on the subsurface transport of oil-field brine at the Osage-Skiatook Petroleum Environmental Research (OSPER) B Site, Oklahoma

As a part of a multidisciplinary study of the impact of oil wells and oil production on the environment, we are investigating the hydrology of the OSPER B site, which is located at Skiatook Lake in Osage County, Oklahoma. Salt and crude oil from oil well brine pits and accidental releases from oil tank batteries have contaminated soil, ground water, and surface water at this site. Preliminary coring near a brine pit at the site showed that beneath 0.5-2 meters of surficial deposits (fill, soil, colluvium, and alluvium), a layer of tight shale that is at least 6 meters thick underlies the site. The land slopes down from the pit at about a 1:10 slope to the lake, which is located about 20 meters from the pit. We found no evidence to date that the brine has penetrated into the shale. Field cores and water level measurements in boreholes indicated that the surficial deposits were often saturated above the shale, which was powder dry. We hypothesize that water from precipitation infiltrates into the permeable surficial deposits, ponds above the low-permeability shale, and moves laterally toward the lake in the surface layer. Dissolved salt from prior spills present in the surface layer is transported down slope to the lake during and following precipitation events. Chemical analyses of water samples collected from boreholes indicate that salt water that collects in the brine pit also moves into the surface layer and flows to the lake. Overland flow and transport of brine also occurs in response to intense rainfall events. Evapotranspiration concentrates the subsurface brine in dry periods. Our field work indicates that the surfacial deposits are very heterogeneous, and as a result there are preferential pathways for subsurface transport of water and contaminants from the pit to the lake. Our results indicate that near-surface, transient processes dominate the contaminant hydrology at this site.

Oklahoma↗
USGS2002

Environmental impacts of petroleum production: The fate of petroleum and other organics associated with produced water from the Osage-Skiatook Petroleum Environmental Research sites, Osage County, OK

We are involved in a multidisciplinary investigation to study the transport, fate, and natural attenuation of inorganic salts, trace metals, radionuclides and organic compounds present in produced water, and their impacts on soil, surface and ground water and the local ecosystem at the Osage-Skiatook Petroleum Environmental Research (OSPER) A and B sites, located in Osage County, OK. About one hectare of land at each of the OSPER A and B sites is affected by salt scarring, soil salinization and brine and petroleum contamination. The main environmental concern results because the sites are adjacent to Skiatook Lake, a 4250-hectare reservoir that provides drinking water to the local communities and is a major recreational fishery. Petroleum wells and tank batteries at the A site have been inactive for some time and the bulk of the hydrocarbon (now degraded and weathered oil) and produced water releases occurred more than 60 years ago. One pit at this site however, contains relatively fresh asphaltic oil and high salinity brine. The B site includes an active production tank battery and adjacent brine and oil pit, an inactive tank battery and an injection well with a small brine pit. For this study oil, gas and/or brine samples were obtained from several oil wells at the B site and areas adjoining the A and B sites, from the two active brine pits at the B site, from the asphaltic pit and adjacent weathered oil pit at the A site and from several of the 40 boreholes (1-71 m deep), recently drilled and completed. Water samples for dissolved organics were obtained from selected boreholes with high salinity water and measurable hydrocarbon gases in the unsaturated zone. Soil and rock core samples were obtained from these selected boreholes to determine the amount and composition of oil sorbed onto the sediments. Finally samples of sediments and/or water from these selected boreholes and from the brine and oil pits were obtained for bacterial characterization. Chemical analysis and bacterial determinations on the collected samples are continuing. Results completed to date show the crude oil source (samples from B and adjacent production wells) is a typical paraffinic-naphthenic light (API gravity of ~35) oil, containing n-alkanes as the dominant components. The four samples examined are identical in their maturity and chemical characteristics. Even though petroleum production is from shallow sandstones (300-600 m depth), these fresh oils show no sign of biodegradation, indicating that bacteria are unable to survive in the associated high salinity (~150,000 mg/L total dissolved solids) brine. Bacterial action, volatilization and water washing are likely responsible for the transformation of source oil to the surficial asphaltic and weathered oil observed at the A site. The leakage of oil with brine from the main active pit at the B site is indicated by the detection of a thin, but discrete oil phase in at least one borehole, the presence of hydrocarbon gases in several boreholes and the smell of oil in many sediment cores from the impacted area located down gradient from this pit. The measured concentrations of DOC, acetate and other organic acid anions, BTEX, phenols and other organics in the source brine are relatively low, but their values in water samples from the impacted areas are not yet available.

Oklahoma↗