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Results for “produced water”

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At least 19 recordsLinked to original sources

PubMed2006

Fuzzy rule-based modelling for human health risk from naturally occurring radioactive materials in produced water.

Produced water, discharged from offshore oil and gas operations, contains chemicals from formation water, condensed water, and any chemical added down hole or during the oil/water separation process. Although, most of the contaminants fall below the detection limits within a short distance from the discharge port, a few of the remaining contaminants including naturally occurring radioactive materials (NORM) are of concern due to their bioavailability in the media and bioaccumulation characteristics in finfish and shellfish species used for human consumption. In the past, several initiatives have been taken to model human health risk from NORM in produced water. The parameters of the available risk assessment models are imprecise and sparse in nature. In this study, a fuzzy possibilistic evaluation using fuzzy rule based modeling has been presented. Being conservative in nature, the possibilistic approach considers possible input parameter values; thus provides better environmental prediction than the Monte Carlo (MC) calculation. The uncertainties of the input parameters were captured with fuzzy triangular membership functions (TFNs). Fuzzy if-then rules were applied for input concentrations of two isotopes of radium, namely (226)Ra, and (228)Ra, available in produced water and bulk dilution to evaluate the radium concentration in fish tissue used for human consumption. The bulk dilution was predicted using four input parameters: produced water discharge rate, ambient seawater velocity, depth of discharge port and density gradient. The evaluated cancer risk shows compliance with the regulatory guidelines; thus minimum risk to human health is expected from NORM components in produced water.

Background Radiation↗

PubMed2002

Oilfield produced water treatment with surface-modified fiber ball media filtration.

In order to explore the PET fiber's potential as a filter medium to treat the water produced from oil production, modification technology was adopted to modify the fiber surface. After modification, the PET fiber surface was grafted by the -COOH, =NH and -OH groups. Therefore, the property of the modified fiber changed from oleophilic to hydrophilic, which makes the fiber easy to backwash. Water produced from atypical oil field in the north of China was treated on site with filter filled with this new fiber medium. The results are compared with the results from a filter filled with currently popular walnut medium, where the experiment conditions are the same as that of the fiber filter. When the velocity is lower than 15 m/h, the effluent from fiber filter can control the oil concentration < 2.4 mg/l, SS < 2.0 mg/l, and D50 < 2 microm, which meets the requirements for waterflood (water injection) into the ground. But the walnut medium filter can only control the oil concentration < 5 mg/l, TSS < 2.0 mg/l, and failed to control the d50 < 2 microm, which is the crucial deficiency of the walnut medium. The fiber medium still shows a great ability to control particles even with higher filtration velocity and worse influent. With a filtration velocity of 20 m/h and 36.4 microm d50 of influent, the d50 of the fiber filter effluent is 3.302 microm, but that of walnut filter is 10.74 microm. The reason for this is due to the compressibiliy of the fiber medium while the walnut median is incompressible. Recommendations for future studies on pilot-scale experiments to improve backwash and to determine operational parameters are presented.

Filtration↗

PubMed1991

Polar, hydrophilic compounds in drinking water produced from surface water. Determination by liquid chromatography-mass spectrometry.

Drinking water produced from surface water may contain many polar, hydrophilic compounds in spite of different treatment steps such as soil filtration, ozone treatment and activated carbon filtration. Little is known about these compounds. The objectives of this work were the detection and identification by means of tandem mass spectrometry (MS-MS) coupled on-line by a thermospray interface with liquid chromatography. Quantification is possible if standard compounds are available. The different compounds in the water extracts were not only separated by means of an analytical column but also using MS-MS after loop injection bypassing the analytical column. Molecular weight information in the loop spectra (overview spectra) and collisionally induced dissociation (CID) made possible the identification of some of these compounds which cannot be eliminated in the drinking water treatment process. Identification was not only done by interpretation of the recorded daughter- and parent-ion spectra but also by comparing them with a laboratory-made daughter-ion library of polar, hydrophilic pollutants. Direct mixture analysis using MS-MS allows the detection and identification of some of the pollutants if they reach the drinking water in the course of the surface water treatment process because of their biochemical and chemical persistence and/or non-sorbability during the soil or activated carbon filtration process. The proposed method for the analysis of water for polar, non-volatile and/or thermolabile organic substances is a quick, specific and powerful technique which makes it possible to detect and identify these substances without any chromatographic separation or derivatization

Chemical Phenomena↗

PubMed2004

Partitioning of semi-soluble organic compounds between the water phase and oil droplets in produced water.

When selecting produced water treatment technologies, one should focus on reducing the major contributors to the total environmental impact. These are dispersed oil and semi-soluble hydrocarbons, alkylated phenols, and added chemicals. Experiments with produced water have been performed offshore on the Statoil operated platforms Gullfaks C and Statfjord B. These experiments were designed to find how much of the environmentally relevant compounds were dissolved in the water phase and not associated to the dispersed oil in the produced water. Results show that the distribution between the dispersed oil and the water phase varies highly for the different components groups. For example the concentration of PAHs and the C6-C9 alkylated phenols is strongly correlated to the content of dispersed oil. Therefore, the technologies enhancing the removal of dispersed oil have a higher potential for reducing the environmental impact of the produced water than previously considered.

Environment↗

PubMed2000

Measurement of oilfield chemical residues in produced water discharges and marine sediments.

During oil production, significant quantities of water are produced with the crude oil which, following treatment on the platform, are discharged to the marine environment. This produced water contains residues of oilfield chemicals added by the platform operators to the topside processing equipment to aid oil-water separation and mitigate operational problems. The levels of oilfield chemicals entering the marine environment via this route were investigated using electrospray ionisation tandem mass spectrometry (ESI-MS/MS) and wet chemical analysis techniques. The generic nature of different chemical types was shown by ESI-MS/MS. Studies of the partitioning behaviour of corrosion inhibitors and demulsifiers between the oil and water phases of the produced fluids suggested corrosion inhibitors partitioned primarily into the aqueous phase and demulsifiers into the oil phase. This was reflected in levels observed in produced water although, in the case of a corrosion inhibitor, lower than expected concentrations were measured. Scale inhibitors were discharged with the produced water at their dosing concentrations. Marine sediments in the proximity of two North Sea oil platforms contained low levels of benzalkonium quaternary ammonium salts (0.74-10.84 ng/g), typical corrosion inhibitor chemicals.

Electron Spin Resonance Spectroscopy↗

PubMed2003

Performance of a hybrid reverse osmosis-constructed wetland treatment system for brackish oil field produced water.

Using constructed wetlands, produced waters from oil fields (i.e., waters that have been in contact with oil in situ) can be treated to enhance water quality for irrigation purposes, or subsequent discharge to receiving aquatic systems. In produced water containing elevated levels of salt (i.e., brackish-produced waters), the ability to decrease the conductivity of the produced water may influence potential reuse of the water for irrigation purposes. The objectives of this research were (1) to determine the efficacy of a pilot-scale hybrid reverse osmosis (RO)-constructed wetland system for treatment and reuse of produced waters from an oil field, and (2) to assess the quality of treated water in terms of physicochemical characteristics and toxicity influencing reuse of the water for irrigation or other designated uses. Specifically, the performance of the hybrid treatment system was examined in terms of outflow water conductivity, total dissolved solids (TDS), and toxicity using Ceriodaphnia dubia and Pimephales promelas in 7-day static/renewal exposure tests. Prior to treatment, significant mortality was observed for C. dubia and P. promelas exposed for 7 days to 6.25% untreated produced water. Following treatment through the hybrid system, no significant mortality was observed in C. dubia or P. promelas exposed to 100% treated produced water when compared to the control organisms. The pilot-scale RO-constructed wetland system effectively decreased conductivity by 95% and TDS by 94% in the brackish produced water tested in this study. Following treatment, the produced water was suitable for irrigation or discharge to surface waters. Therefore, hybrid RO-constructed wetland treatment systems present a viable alternative for treatment and reuse of produced waters from oil fields.

Agriculture↗

PubMed2006

Oil well produced water discharges to the North Sea. Part II: comparison of deployed mussels (Mytilus edulis) and the DREAM model to predict ecological risk.

Large volumes of water often are produced with oil and gas from offshore platforms. The produced water is separated from the oil and gas and either reinjected into a deep formation or discharged to the ocean. The Norwegian oil and gas industry advocates ecological risk assessment as the basis for managing produced water discharges to the North Sea. In this paper, we compare estimates of ecological risks to water-column communities based on data on hydrocarbon residues in soft tissues of blue mussels deployed for a month near offshore platforms and based on predictions of the Dose related Risk and Effect Assessment Model (DREAM). The study was performed near produced water discharges to the Tampen and Ekofisk Regions of the Norwegian Sector of the North Sea. Because polycyclic aromatic hydrocarbons (PAH) are considered the most important contributors to the ecological hazard posed by produced water discharges, comparisons made here focus on this group of compounds. The mussel approach is based on predicted environmental concentrations (PECs) of individual PAH, estimated from PAH residues in mussels following deployment for a month near several produced water discharges, and predicted no effects concentrations (PNECs) based on a K(ow) regression model. In the DREAM method, PECs for three PAH fractions are estimated in the three-dimensional area around produced water discharge with the DREAM model. PNECs for each fraction are based on the chronic toxicity of a representative PAH from each fraction divided by an assessment factor to account for uncertainty in the chronic value. The mussel method gives much lower estimates of ecological risk than the DREAM method. The differences are caused by the much lower PNECs used in DREAM than derived from the regression model, and by the lower concentrations of aqueous PAH predicted by DREAM than estimated from PAH residues in mussel tissues. However, the two methods rank stations at different distances from produced water discharges in the same order and both identify 2- and 3-ring PAHs as the main contributors to the ecological risk of produced water discharges. Neither method identifies a significant ecological risk of PAH in the upper water column of the oil fields. The DREAM model may produce an overly conservative estimate of ecological risk of produced water discharges to the North Sea.

Animals↗

PubMed2005

Aerobic spore-forming bacteria for assessing quality of drinking water produced from surface water.

Cryptosporidium and Giardia represent a major microbiological issue for drinking water production from surface water. As their monitoring through a treatment process is rather tedious and as low-concentration goals should be reached for drinking water, aerobic spore-forming bacteria (ASFB) have been studied as an indicator microorganism for a drinking water treatment plant using surface water. The results reveal that monitoring naturally occurring ASFB better highlights daily achievable performances and identifies unusual process events for global disinfection, for both physical and chemical treatment steps in a multi-barrier drinking water treatment plant. Advantages of ASFB over usual process parameters are that these microorganisms are more sensitive to process fluctuations. The use of ASFB also showed that the efficiency of ozone disinfection is not as significantly influenced by the water temperature as reported, despite similar or higher CT values applied during warmer periods. Thus, the disinfection of resistant microorganisms with ozone can also be an efficient process at lower water temperature. ASFB have been shown to be a conservative indicator for Cryptosporidium and Giardia up to a 1st stage filtration and the ASFB Log removals can be used to estimate Log removals for Cryptosporidium and Giardia: compared to ASFB, the Log removals for Cryptosporidium or Giardia are at least equal or 50% higher, respectively. Thus, the monitoring of ASFB along a drinking water treatment process could be a useful tool for performing risk analysis for parasites such as Cryptosporidium and Giardia, and would further allow integration of daily variability into a risk analysis.

Animals↗

PubMed2006

Removal of oil from produced water by coalescence/filtration in a granular bed.

Oil production generates a significant amount of water byproduct known as produced water. Following primary gravity separation, produced water is normally disposed of by injection into the formation from which it came. However, high amounts of suspended solids or oil in the produced water may cause clogging of the injection formation. This study evaluated the effectiveness of coalescence/filtration in treating two produced water samples obtained from Saskatchewan heavy oil production sites. In the coalescence/filtration experiments, percentage removals of oil and suspended solids were observed to be as high as 97 and 91 percent, respectively. Mechanisms of filtration and coalescence were identified and observed through experimental data and mathematical models. The maximum coalescence efficiency observed was three percent at the lowest flow rate. Coalescence efficiencies decreased with increasing flow rate. Experimental data for single and two-phase flow were shown to fit the Carmen-Kozeny filtration equation. Coalescence/filtration satisfied a first order rate equation using the Crickmore model.

Filtration↗

PubMed2006

Precipitation of heavy metals in produced water: influence on contaminant transport and toxicity.

Produced water undergoes changes in its physical chemistry including precipitation of heavy metals after being discharged and mixed with ambient seawater. Potential impacts of the precipitation of heavy metals on their transport and toxicity were studied using samples from offshore oil production sites on the Scotian Shelf off eastern Canada. Concentrations of aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel and zinc were measured in total, particulate and dissolved fractions together with Microtox tests for assessment of toxicity. Heavy metals in produced water were transformed from dissolved to particulate phase in a period of hours under oxygenated conditions, and aggregated to larger particles that settle rapidly (>100 m/day) over a few days. In addition, there was production of buoyant particles comprised of heavy metal precipitates sequestered onto oil droplets that were transported to the surface. The particulate fraction was generally more toxic than the dissolved fraction. This was evident at the mixing interface between produced water and seawater where elevated particulate and toxicity levels were observed. Laboratory studies suggest an increase in the toxicity of discharged produced water over time. Time-series experiments showed a sustained toxic response for more than a week following the oxidation of freshly discharged produced water that initially elicited little or no toxic response in the Microtox test. Chemical processes identified in this study, namely precipitation of heavy metals and consequent settling and rising fluxes of particles, will influence the toxicity, the fate and the transport of potential contaminants in the produced water. Therefore, these processes need to be considered in assessment of the environmental impact associated with offshore oil and gas operations.

Chemical Precipitation↗

PubMed2005

Managing disposal of water produced with petroleum in Kuwait.

Disposal of water produced with petroleum has been of great interest in Kuwait for the last 20 years. The current problem arose when the Burgan oil field, which is the second largest field in the world, experienced successive increases in the water content of the produced oil. This study introduces a decision-making analysis of the considered alternatives for the disposal of the produced water. Four alternative solutions exist for the industry as practical solutions for the disposal of water produced in Kuwait. The first method utilizes a large number of pits to discharge water. The second alternative depends on discharging water into sealed pits. The third approach to dispose water is by injecting the water underground. The last method is similar to the previous one, but takes into consideration the recovery of reservoir pressure to maintain the rate of oil production. A questionnaire was distributed to 48 experts at the top management level of the petroleum companies and the governmental authority. The data collected considered cost, efficiency, and environmental parameters. Based on the data, a statistical analysis was conducted using the factor analysis method to reduce the number of investigated variables. The analysis concluded that the optimal solution is to use the effluent injection method to discharge water produced with oil in Burgan and similar fields in Kuwait.

Data Collection↗

PubMed2004

Utilization of solar energy in the photodegradation of gasoline in water and of oil-field-produced water.

The photo-Fenton process utilizes ferrous ions (Fe2+), hydrogen peroxide (H2O2), and ultraviolet (UV) irradiation as a source of hydroxyl radicals for the oxidation of organic matter present in aqueous effluents. The cost associated with the use of artificial irradiation sources has hindered industrial application of this process. In this work, the applicability of solar radiation for the photodegradation of raw gasoline in water has been studied. The photo-Fenton process was also applied to a real effluent, i.e., oil-field-produced water, and the experimental results demonstrate the feasibility of employing solar irradiation to degrade this complex saturated-hydrocarbon-containing system.

Chromatography, Gas↗

PubMed2004

Organic matrix in produced water from the Osage-Skiatook petroleum environmental research site, Osage county, Oklahoma.

Produced water (water co-produced with oil and gas) constitutes the single largest waste stream for oil and gas industry. Reclaiming this water for beneficial use is thought to be one of the most practical solutions that can solve both environmental and water shortage problems. The feasibility of this practice depends on the ability to remove its chemical content to the levels that meets the appropriate standards. Organic compounds are probably the most difficult fraction to handle. In this paper, the discrete organic compounds and non-volatile, macromolecular organic compounds (i.e., natural organic matter--NOM) of three produced water samples from the Osage-Skiatook Environmental Research site were characterized. Two of the three produced waters had very little contribution from NOM, while one of the samples had about 23% NOM contribution to its organic matrix pool. Fluorescent spectrophotometric scans provided little differentiation among the organic quality of the produced water, while pyrolysis-GC/MS showed that the NOM characteristics of the three produced waters were distinct. Specifically, the overall halogenated content and aromaticity of the NOM were found to be possible qualifiers that distinguish produced water from the coalbed methane well from produced water from the oil well. And the specific chemical fragments that are linked to polysaccharide sources were found to be potential identifiers that distinguish produced water from the newer oil well from produced water from the older oil well. These identifiers were, however, only suggested for this preliminary study. More samples must be included to build a substantial database on produced water NOM to confirm and identify more markers.

Gas Chromatography-Mass Spectrometry↗

PubMed2004

Identification of in vitro estrogen and androgen receptor agonists in North Sea offshore produced water discharges.

The estrogen receptor (ER) agonist potency of offshore produced water discharges was examined via bioassay-directed chemical analysis. The in vitro estrogen receptor (ER) and androgen receptor (AR) agonist potency of five produced water samples collected from oil-production platforms in the British and Norwegian sectors of the North Sea was determined by using the yeast estrogen and androgen screens. Produced water samples were extracted in situ on the production platforms by using large-volume solid-phase extraction. All five extracts tested positive for the presence of ER agonists, whereas no AR agonist activity could be detected. By using the yeast estrogen screen assay in association with bioassay-directed fractionation, attempts were made to identify the ER agonist compounds present in the produced water extracts. The fractionation procedure used cyano-amino-bonded silica normal-phase high-performance liquid chromatography to isolate estrogenic compounds from produced water extract followed by full-scan gas chromatography-electron-impact mass spectrometry (GC-(EI)MS) to identify them. Isomeric mixtures of C1 to C5 and C9 alkylphenols contributed to the majority of the ER agonist potency measured in the samples.

Androgens↗

PubMed2006

Surface flow constructed wetland for heavy oil-produced water treatment.

Heavy oil-produced water from China' Liaohe Oilfield was purified in a surface flow constructed wetland (SFCW) during a 3-yr field experiment. Treatment showed high mean removal efficiencies of 80%, 93%, 88% and 86% for COD, oil, BOD and TKN, respectively for reed bed #1 and 71%, 92%, 77%, and 81% for COD, oil, BOD and TKN, respectively for reed bed #2. The results also showed that in the third year of the system's operation, the oil-produced water had mainly positive impacts on the reed's health parameters. Thus, reed can be used as a feasible wetland macrophyte for treating such wastewater, and this SFCW system can operate for a long time.

Petroleum↗

PubMed2004

Integrated fate modeling for exposure assessment of produced water on the Sable Island Bank (Scotian shelf, Canada).

Produced water is the largest waste discharge from the production phase of oil and gas wells. Produced water is a mixture of reservoir formation water and production chemicals from the separation process. This creates a chemical mixture that has several components of toxic concern, ranging from heavy metals to soluble hydrocarbons. Analysis of potential environmental effects from produced water in the Sable Island Bank region (NS, Canada) was conducted using an integrated modeling approach according to the ecological risk assessment framework. A hydrodynamic dispersion model was used to describe the wastewater plume. A second fugacity-based model was used to describe the likely plume partitioning in the local environmental media of water, suspended sediment, biota, and sediment. Results from the integrated modeling showed that the soluble benzene and naphthalene components reach chronic no-effect concentration levels at a distance of 1.0 m from the discharge point. The partition modeling indicated that low persistence was expected because of advection forces caused by tidal currents for the Sable Island Bank system. The exposure assessment for the two soluble hydrocarbon components suggests that the risks of adverse environmental effects from produced water on Sable Island Bank are low.

Canada↗

PubMed2006

Spatial and monthly variations of radium isotopes in produced water during oil production.

Spatial and monthly variations of radium isotope concentrations in produced water have been evaluated during oil production. Samples of produced water were collected and analyzed on a monthly basis over a period of 5 months, the samples being derived from 11 main oil production wells at three Syrian oilfields. The highest average 226Ra, 228Ra and 224Ra concentrations in these samples of water were found to be 41, 37.5 and 1.1 Bql(-1), respectively. The data obtained for 226Ra, 228Ra and the 228Ra/226Ra activity ratio were evaluated statistically and displayed using the Box Plot method; clear variations can be observed from one field to another, indicating differences in the geological formation of the reservoir. The 228Ra/226Ra activity ratio variations reflect the variability of the Th/U mass ratio of the geological formation, suggesting two different source rock types. The calculated mean Th/U mass ratio for these two possible types of source rock were 2.4 and 5.78. In addition, the 228Ra/226Ra mean activity ratio was also used to estimate the age of some deposited scales in tubulars; the results were compared with the 224Ra/228Ra activity ratio dating method. Monthly variations of 226Ra and 228Ra activity concentrations and the 228Ra/226Ra activity ratio in produced water were also observed, the major causes for these variations being related to the type of injection water and interwell reactions. Possible relationships between 226Ra and 228Ra activity concentrations, the 228Ra/226Ra activity ratio and physical and chemical properties of produced water were statistically evaluated; no linear correlations were found.

Journal Article↗

PubMed2003

Comparing methods and sediment contaminant indicators for determining produced water fate in a Louisiana estuary.

Produced water is a high salinity by-product resulting from oil and gas production. Disposal methods include surface water discharge. The current field method used to determine its fate in estuarine systems involves extending a compass oriented transect (COT) from the point source discharge--a method designed for a uniformly dispersing effluent discharged into a uniform offshore environment that may be inappropriate for the hydrologic and geomorphologic complexities found in estuarine systems. Prior research established the viability of the salinity stratification transect (SST) method. Both COT and SST methods were used in a small open bay to determine which more accurately detected effluent dispersion. Determination was based on sediment contaminant indicators (SCIs), including interstitial salinity, hydrocarbons, metals, and radium concentrations. Additionally, SCIs were evaluated for their ability to serve as indicators of effluent dispersion. The data revealed that SST stations exhibited higher contaminant concentrations and that this approach was more accurate in tracking the produced water plume. The data also suggested that SCIs varied in their ability to serve as indicators. Good indicators included interstitial salinity, total targeted aromatic hydrocarbons substantiated with a modified fossil fuel pollution index value, certain metals, and radium-228.

Environmental Monitoring↗