Purification of Produced Water from a Sour Oilfield in South Kuwait. 2. Oil-Water Separation and Crystallization of Calcium Carbonate

Oil-water separation for produced water (PW) originating from an oil extraction site in South Kuwait was carried out using bleached, esterified cellulosic material from used coffee grounds. Thereafter, earth-alkaline metal ions, specifically calcium ions, of the de-oiled PW were removed by precipitation with sodium carbonate to give access to pure sodium chloride as industrial salt from the remaining PW. While the purity of the precipitated calcium carbonate (CaCO3) depends on the precipitation conditions, CaCO3 of up to 95.48% purity can be obtained, which makes it a salable product. The precipitation of CaCO3 decreases the amount of calcium ions in PW from 11,300 ppm to 84 ppm.

Purification of Produced Water from a Sour Oilfield in South Kuwait. 1. Oil-Water Separation and Industrial Salt Production

Produced water from an oil extraction site in South Kuwait was sampled after primary oil – water separation had been carried out. The produced water was filtered through a mixture of activated charcoal and esterified cellulosic material gained from spent coffee grounds as a tertiary adsorption treatment. The earth-alkaline metal ions and heavy metals were separated from the de-oiled produced water by addition of either sodium or potassium hydroxide in the presence of carbon dioxide or by direct addition of solid sodium carbonate. The resulting filtrate gave salt of industrial purity upon selective crystallization on evaporation.

Variability in Quantity and Salinity of Produced Water from an Oil Production in South Kuwait

Produced water (PW) is the largest waste stream in the oil and gas industry. Water remains trapped for millions of years in the reservoir with oil and gas. When a hydrocarbon reservoir is infiltrated by a production well, the produced fluids commonly contain water. The understanding of this water’s constituents and volumes is vital for the sustainable continuity of production operations, as PW has a number of negative impacts on the infrastructure integrity of the operation. On the other hand, PW can be an alternative source of irrigation water as well as of industrial salt. Interestingly, both the quantity as well as the quality of PW do not remain constant but can vary, both progressively and erratically, even over short periods of time. This paper discusses such a situation of variable PW in an oil and gas operation in the State of Kuwait.

Effects of the Produced Water from a Sour Oilfield in South Kuwait on the Production Tubing

Kuwaiti oil production faces a growing challenge in the increasing quantities of produced water generated in the production of oil. The high water cut of the produced fluid from the wells and the high salinity of the produced water lead to significant degradation of subsurface equipment, specifically the production tubing. Debris generated through the degradation of the inner part of the tubing becomes a constituent of the scaling that deposits in the tubing and blocks the flow of the production fluid, inducing higher maintenance costs. This paper looks at the characteristics of the scaling in regard to the produced water and outlines the economic impact of the produced water induced degradation of the tubing structure.

Flux enhancement during ultrafiltration of produced water using turbulence promoter

Concentration polarization and membrane fouling remain one of the major hurdles for the implementation of ultrafiltration of produced water. Although many applications for ultrafiltration were already suggested, only few were implemented on an industrial scale. Among those techniques, turbulence promoter can be more simple and effective in overcoming membrane fouling and enhancing membrane flux. As for the result that turbulence promoter increase fluid velocity, wall shear rates and produce secondary flows or instabilities, the influence of turbulence promoter was investigated on permeate flux during produced water ultrafiltration and the potential application of this arrangement for an industrial development. Experimental investigations were performed on 100 KDa molecular weight cut-off PVDF single-channel tubular membrane module using four kinds of turbulence promoters. It is observed that the significant flux enhancement in the range of 83%--164% was achieved while the hydraulic dissipated power per unit volume of permeate decreased from 31%--42%, which indicated that the using of turbulence promoter is more efficient than operation without the turbulence promoter. The effects of transmembrane pressure and cross-flow velocity with and without turbulence promoter were studied as well. Among the four kinds of turbulence promoters, winding inserts with 20.0 mm pitch and 1.0 mm wire diameter showed better performances than the others did.

Influences of water treatment agents on oil-water interfacial properties of oilfield produced water

The emulsion stability of oilfield produced water is related to the oil-water interfacial film strength and the zeta potential of the oil droplets. We investigated the effects of water treatment agents （corrosion inhibitor SL-2, scale inhibitor HEDP, germicide 1227, and flocculant polyaluminium chloride PAC） on the stability of oilfield produced water. The influence of these treatment agents on oil-water interfacial properties and the mechanism of these agents acting on the oilfield produced water were studied by measuring the interfacial shear viscosity, interfacial tension and zeta electric potential. The results indicated that the scale inhibitor HEDP could increase the oil-water interfacial film strength, and it could also increase the absolute value of the zeta potential of oil droplets. HEDP played an important role in the stability of the emulsion. Polyaluminum chloride （PAC） reduced the stability of the emulsion by considerably decreasing the absolute value of the zeta potential of oil droplets. Corrosion inhibitor SL-2 and germicide 1227 could decrease the oil-water interfacial tension, whereas they had little influence on oil-water interfacial shear viscosity and oil-water interfacial electricity properties.

Produced Water from Oil and Gas Exploration—Problems, Solutions and Opportunities

Large volumes of water are generated in gas- and oil-production. This includes the water that is present originally in the reservoirs, but also water that is injected into the wells. While currently much of the produced water is either reinjected or disposed of after treatment, treated produced water is increasingly seen as an interesting resource, especially in water-scarce regions. This review looks at different PW treatment methods available, with an emphasis on the management of PW in oil- and gas production on the Arabian Peninsula.

Characteristics of dissolved inorganic carbon in produced water from coalbed methane wells and its geological significance

Based on long-term dynamic tracing of dissolved inorganic carbon(DIC)and stable carbon isotope(δ13CDIC)in produced water from 20 coalbed methane(CBM)wells in western Guizhou,the spatial-temporal dynamic variations ofδ13CDIC of the GP well group produced in multi-layer commingled manner were analyzed,and the relationship between the value ofδ13CDIC and CBM productivity was examined.The produced water samples of typical wells in the GP well group were amplified and sequenced using 16S rDNA,and a geological response model ofδ13CDIC in produced water from CBM wells with multi-coal seams was put forward.The research shows that:δ13CDIC in produced water from medium-rank coal seams commonly show positive anomalies,the produced water contains more than 15 species of methanogens,and Methanobacterium is the dominant genus.The dominant methanogens sequence numbers in the produced water are positively correlated withδ13CDIC,and the positive anomaly of v is caused by reduction of methanogens,and especially hydrogenotrophic methanogens.Vertical segmentation of sedimentary facies and lithology in stratum with multi-coal seams will result in permeability and water cut segmentation,which will lead to the segmentation ofδ13CDIC and archaea community in produced water,so in the strata with better permeability and high water cut,theδ13CDIC of the produced water is abnormally enriched,and the dominant archaea is mainly Methanobacterium.In the strata with weak permeability and low water cut,theδ13CDIC of the produced water is small,and the microbial action is weak.The shallow layer close to the coal seam outcrop is likely to be affected by meteoric precipitation,so theδ13CDIC of the produced water is smaller.The geological response model ofδ13CDIC in produced water from multi-coal seams CBM wells in the medium-rank coal reveals the geological mechanism and microbial action mechanism of theδ13CDIC difference in the produced water from the multi-coal seams CBM wells.It also provides effective geochemical evidence for the superimposed fluid system controlled by sedimentary facies,and can also be used for the contribution analysis of the produced gas and water by the multi-layer CBM wells.

Perikinetics and sludge study for the decontamination of petroleum produced water(PW) using novel mucuna seed extract

In this study, Mucuna flagellipes seed extract was applied in the coagulation-flocculation of produced water （PW）. Process parameters such as pH, dosage, and settling time were investigated. Process kinetics was also studied. Instrumental characterization of mucuna seed （MS）, mucuna seed coagulant （MSC）, and post effluent treatment settled sludge （PTSS） were carried out. The optimum decontamination efficiency of 95 % was obtained at 1 g/L MSC dosage, PW pH of 2, and rate constant of 0.0001 （L/g/s）. Characterization results indicated that MS, MSC, and PTSS were of network structure, primitive lat- tice, and thermally stable. It could be concluded that MSC would be potential biomass for the treatment of produced water under the experimental conditions.

Removal of ions from produced water using Powder River Basin coal

In addition to being used as an energy source,coal also has significant potential for other,more sustainable uses including water treatment.In this study,we present a simple approach to treat water that was produced during oil production and contained a total dissolved solids(TDS)content of over 150 g/L using Powder River Basin(PRB)coal.PRB coal used as packing material in a flow-through column effectively removed 60%–80%of the cations and anions simultaneously.Additionally,71%–92%of the total organic carbon in the produced water was removed as was all of the total suspended solids.The removal mechanisms of both cations and anions were investigated.Cations were removed by ion exchange with protons from oxygen-containing functional groups such as carboxylic and phenolic hydroxyl groups.Anions,mainly Cl−1,appeared to be removed through either the formation of resonance structures as a result of delocalization of electrons within coal molecules or through ion–πinteractions.We propose that coal is a“pseudo-amphoteric”exchange material that can remove cations and anions simultaneously by exchanging ions with both ionized and non-ionized acids that are ubiquitous in coal structure or resonance effect.

Corrosion Behavior of Pipeline Steel in Oilfield Produced Water under Dynamic Corrosion System

In order to predict the corrosion trendency of X100 pipeline steel in flowing oilfield produced water,the effect of flow rate on the corrosion behavior of X100 pipeline steel was studied under general dynamic condition and simulated real working condition at the flow rate of 0.2,0.4,and 0.6 m·s^(-1).Potentiodynamic polarization curves and electrochemical impedance spectroscopy were used to study the corrosion behavior of X100 steel.Energy dispersive spectroscopy,X-ray diffraction and scanning electron microscopy were used to analyze corrosion product composition and micromorphology.The experimental results show that the corrosion is more serious under simulated real working conditions than that under the general dynamic conditions.In any case the corrosion current density increases with the increase of the flow rate,and the total impedance value decreases.The corrosion products include Fe_(3)O_(4),Fe_(2)O_(3),and FeOOH.The mass transfer and electrochemistry were simulated by flow coupled in COMSOL software.The multiphysical field coupling simulation results are closer to the engineering practice than the single flow field simulation,and similar results from the experiments were obtained.Both experimental and simulation results reveal that the higher flow rate is,the more serious corrosion appear and the more corrosion products accumulate.By combining experimental and COMSOL simulation data,the corrosion process model of X100 steel was proposed.

Review on the Estimating the Effective Way for Managing the Produced Water: Case Study

Water manufactured is the primary waste source in the oil and gas industry. Because of the rising amount of waste worldwide, the environmental effect of wastewater has become a primary environmental concern in recent years. The vast amounts involved have resulted in considerable costs to the industry for handling produced water. This research explains the wide variety of choices for water management. This research’s first phase was water minimization techniques, consisting of three different applications made in three different wells (Well 1, Well 2 and Well 3) and water recycling and reuse by two techniques. In Well 1, Mechanical shut-off technique was applied using through tubing bridge plug and 5 m cement dumped above it to isolate the watered out zone;as per water oil ration plot the water cut is decreased from 100% to 4% and the production is increased from 0 to 400 bcpd. In Well 2, Chemical shut-off technique using a polymer called Brightwater has been used to block channeling through high permeability intervals after PLT log detected it, and the result was brilliant, the water cut decreased from 60% to 25%, also the oil production increase from 500 to 3000 bopd. In Well 3, downhole separator installed in it using workover (unfortunately, this technique is not applied in middle east till the moment so this application is taken from an oil field in Canada)and the result was perfect, the water cut decreased from 70% to 28%, also the oil production increase from 44 to 100 bopd. This study tried to clarify and compare the most widely used water management techniques using one of the Western Desert (W.D.) (enhanced for oil recovery, constructed wetland).

Microfiltration,ultrafiltration and nanofiltration as a post-treatment of biological treatment process with references to oil field produced water of Moran oilfield of Assam

The selection of an apt technology for the treatment of Oilfield Produced Water(OFPW)depends mainly on the quality of OFPW and methods of pre-and post-treatment processes.The most challenging part of the OFPW treatment process is the removal of Suspended Solid(SS),Oil&Grease(O&G)and dissolved organics.SS and O&G pose an acute problem to the membrane filtration system by fouling the membrane surface which increases operation&maintenance costs and decreases the life of the membrane.Fouling of the membrane surface is mainly attributed to the presence of low molecular weight aromatic compounds and naphthenic acids in the suspended and dissolved organic compounds.Thus,the removal of these suspended and dissolved organic compounds before membrane filtration proffers a challenge to the researchers.In this research,bioremediation process has been applied to remove the organic compounds and the performance and fouling behaviour of hollow fibre Microfiltration(MF),Ultrafiltration(UF)and Nanofiltration(NF)membranes after the bioremediation process has been analyzed in detail.The level of toxicity was determined by comparing the pollutants with the safe discharge limit for disposal into the environment set by Central Pollution Control Board(CPCB),India.The research presents its novelty by using a hydrocarbon-degrading bacteria,Pseudomonas aeruginosa for the Reduction of Organic Loads(ROL)from OFPW of Moran oil field of Upper Assam as a pre-treatment to membrane filtration.The Total Sum Corrected Area(TSCA)method through chromatographic analyses was used for this.The organic loads removal from OFPW by the TSCA method was found to be 67-100%,100%and 100%after 7,14 and 21 days of bioremediation respectively.The major parameters in feed OFPW of Moran oil field were found to be pH(7.5-9.3),Total Dissolved Solid(TDS)(1.79-4.75)ppt,O&G(1.78-2.8)ppt,Salinity(2.94-6.98)ppt,Chloride(Cl^(-))(1.6-3.86)ppt,Bicarbonate(HCO_(3)^(-))(2.89-4.03)ppt.It was observed that the ranges of pollutants removal by NF was highest such as TDS(26-86%),salinity(81-86%),turbidity(78-94%),hardness(67-75%),O&G(96-99%),Cl^(-)(80-89%)and HCO_(3)^(-)(95-97%).

Physicochemical assessment and treatment of produced water:A case study in Niger delta Nigeria

The most important waste stream created during oil and gas production is oilfield-produced water.When discharged without treatment,it poses a significant risk of pollution of marine ecosystems.While adequate treatment before disposal is acceptable,achieving authorized discharge criteria continues to be a problem for the petroleum sector.This research examined the physicochemical characteristics of produced water at various month intervals before and after treatment.Heavy metal and organic component concentrations in water samples were determined using atomic absorption spectroscopy and gas chromatography.The results indicate that produced water from a certain Niger Delta oilfield contains significant amounts of heavy metals and some organic compounds after treatment.The present laws,as well as the measurement of dispersed oil and grease content,have been in place for a long period of time without considerable change,even though most dangerous components in produced water are dissolved.It is recommendable for the prospective field developers/operators to consider the dissolved components of produced water and consider the economic consequences of adopting tertiary produced water polishing technologies.

A review of crosslinked fracturing fluids prepared with produced water

The rapidly increasing implementations of oilfield technologies such as horizontal wells and multistage hydraulic fracturing,particularly in unconventional formations,have expanded the need for fresh water in many oilfield locations.In the meantime,it is costly for services companies and operators to properly dispose large volumes of produced water,generated annually at about 21 billion barrels in the United States alone.The high operating costs in obtaining fresh water and dealing with produced water have motivated scientists and engineers,especially in recent years,to use produced water in place of fresh water to formulate well treatment fluids.The objective of this brief review is to provide a summary of the up-to-date technologies of reusing oilfield produced water in preparations of a series of crosslinked fluids implemented mainly in hydraulic fracturing operations.The crosslinked fluids formulated with produced water include borate-and metalcrosslinked guar and derivatized guar fluids,as well as other types of crosslinked fluid systems such as crosslinked synthetic polymer fluids and crosslinked derivatized cellulose fluids.The boratecrosslinked guar fluids have been successfully formulated with produced water and used in oilfield operations with bottomhole temperatures up to about 250
F.The produced water sources involved showed total dissolved solids(TDS)up to about 115,000 mg/L and hardness up to about 11,000 mg/L.The metal-crosslinked guar fluids prepared with produced water were successfully used in wells at bottomhole temperatures up to about 250
F,with produced water TDS up to about 300,000 mg/L and hardness up to about 44,000 mg/L.The Zr-crosslinked carboxymethyl hydroxypropyl guar(CMHPG)fluids have been successfully made with produced water and implemented in operations with bottomhole temperatures at about 250t
F,with produced water TDS up to about 280,000 mg/L and hardness up to about 91,000 mg/L.In most of the cases investigated,the produced water involved was either untreated,or the treatments were minimum such as simple filtration without significantly changing the concentrations of monovalent and divalent ions in the water.Due to the compositional similarity(high salinity and hardness)between produced water and seawater,crosslinked fluids formulated with seawater for offshore and onshore jobs were also included.The crosslinked guar and derivatized guar fluids have been successfully formulated with seawater for operations at bottomhole temperatures up to about 300
F.Operating costs have been significantly reduced when produced water or seawater is used to formulate fracturing fluids in place of fresh water.With various challenges and limitations still existing,the paper emphasizes the needs for new developments and further expansion of produced water reuse in oilfield operations.

Treatment of oilfield produced water by anaerobic process coupled with micro-electrolysis

Treatment of oilfield produced water was investigated using an anaerobic process coupled with micro-electrolysis （ME）, focusing on changes in chemical oxygen demand （COD） and biodegradability. Results showed that COD exhibited an abnormal change in the single anaerobic system in which it increased within the first 168 hr, but then decreased to 222 mg/L after 360 hr. The biological oxygen demand （five-day） （BOD5）/COD ratio of the water increased from 0.05 to 0.15. Hydrocarbons in the wastewater, such as pectin, degraded to small molecules during the hydrolytic acidification process. Comparatively, the effect of ME was also investigated. The COD underwent a slight decrease and the BOD5/COD ratio of the water improved from 0,05 to 0.17 after ME. Removal of COD was 38.3% under the idealized ME conditions （pH 6.0）, using iron and active carbon （80 and 40 g/L, respectively）. Coupling the anaerobic process with ME accelerated the COD removal ratio （average removal was 53.3%）. Gas chromatography/mass spectrometry was used to analyze organic species conversion. This integrated system appeared to be a useful option for the treatment of water produced in oilfields.

Geochemical Characters of Water Coproduced with Coalbed Gas and Shallow Groundwater in Liulin Coalfield of China

To reveal the geochemical characters of water coproduced with coalbed gas and shallow groundwater,water samples were collected from 12 wells of coalbed methane and 7 wells of shallow groundwater.The pH,CODMn,fCO2,total dissolved solids （TDS）,total hardness,and concentrations of metasilicic acid,sodium and kalium,calcium ion,magnesium ion,ammonium iron,bicarbonate ion,carbonate,chloride,sulfate ion,nitrate ion,fluoride,lithium,zinc,nickel,manganese,iron,boron,barium,etc.of the samples were measured.Research results showed the following：（1） Concentrations of TDS,chloride,fluoride,sodium and kalium,ammonium,iron,and barium in the water coproduced with coalbed gas exceeded the national standards of China; however,physical,chemical,and biological properties of shallow groundwater could meet the national standard.（2） The water produced from coalbed contained mainly Na-Cl·HCO3,with average TDS of 4588.5 ppm,whereas shallow groundwater contained a mixture of chemicals including Na.Mg.Ca-HCO3·SO4 and Na.Mg-HCO3·SO4,with average TDS of 663.8 ppm.（3） In general,it was observed that bicarbonate and sodium accumulated in a reducing environment and deeper system,while depletion of hydrogen ions and dissolution of sulfate,calcium,and magnesium occurred in a redox environment and shallow system.（4） Sodium and kalium,ammonium,chloride,and bicarbonate ions were the main ions found in the study area.

Sludge characterization and treatment of produced water(PW)using Tympanotonos Fuscatus coagulant(TFC)

This study investigated coag-flocculation(using TFC)of PW and characterization of the post treatment settled sludge(PTSS).Effects of dosage,pH and settling time on treatment efficiency were evaluated.TFC and PTSS were subjected to Fourier transform infrared(FTIR),Xeray diffraction(XRD),Thermogravimetric/Differential scanning calorimetric and Scanning electron microscopic(SEM)/Elemental analyses.Optimal treatment efficiency of 91.5%was obtained at 1 g/L and pH 2.It could be concluded that TFC was thermally stable and has potential for application as an effective bio-coagulant.

Temporal variations in geochemistry of hydraulic fracturing fluid and flowback water in a tight oil reservoir

Hydraulic fracturing facilitates the development and exploitation of unconventional reservoirs.In this study,the injected hydraulic fracturing fluid(HFF)and flowback and produced water(FPW)in tight oil reservoirs of the Lucaogou Formation in the Junggar Basin are temporally sampled from day 1 to day 64.Freshwater is used for fracturing,and HFF is obtained.The chemical and isotopic parameters(including the water type,total salinity,total dissolved solids(TDS),pH,concentrations of Na^(+),Cl^(-),Ba^(+),K^(+),Fe^(2+)+Fe^(3+),and CO_(3)^(2-),dD,and δ^(18)O)are experimentally obtained,and their variations with time are systematically analyzed based on the flowback water.The results show that the water type,Na/Cl ratio,total salinity,and TDS of the FPW change periodically primarily due to the HFF mixing with formation water,thus causing δD and δ^(18)O to deviate from the meteoric water line of Xinjiang.Because of watererock interaction(WRI),the concentrations of Fe^(2+)+Fe^(3+)and CO_(3)^(2-)of the FPW increase over time,with the solution pH becoming more alkaline.Furthermore,based on the significant changes observed in the geochemistry of the FPW,three separate time intervals of flowback time are identified:Stage Ⅰ(<10 days),where the FPW is dominated by the HFF and the changes in ions and isotopes are mainly caused by the WRI;Stage Ⅱ(10-37 days),where the FPW is dominated by the addition of formation water to the HFF and the WRI is weakened;and finally,Stage Ⅲ(>37 days),where the FPW is dominated by the chemistry of the formation water.The methodology implemented in this study can provide critical support for the source identification of formation water.

Progression of injectivity damage with oily waste water in linear flow

Numerous laboratory experiments and field cases show that even very small amount of oil in injected water can cause severe injectivity damage. Although injectivity decline caused by oil droplets has been studied experimentally, there is still lack of an easy-to-use and widely accepted model to predict the decline behavior. In this work, we developed an analytical model to predict the time-dependent progress of the water permeability reduction in linear flow by analyzing experimental data obtained from linear core flooding. The model considers mass transfer of the oil phase from the produced water to the rock due capture effects by dispersion, advection and adsorption inside the rock. As the captured oil saturation increases, permeability reduces following the relative permeability drainage relationship. The reduction stabilizes when the oil saturation comes to an equilibrium value controlled by oil droplet size and injection velocity. The model is calibrated using published experimental data from prolonged core floods with oil- contaminated waste water. Theoretical runs of the model replicate all the effects known from experimental observations. Resulting from the model is a distributed change of permeability vs. time and distance from the point of injection that can be converted to the overall injectivity damage.