Download or read book Experimental Investigation of Low Salinity Water Flooding to Improve Viscous Oil Recovery from the Schrader Bluff Reservoir on Alaska North Slope written by 程耀泽 and published by . This book was released on 2018 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alaska's North Slope (ANS) contains vast resources of viscous oil that have not been developed efficiently using conventional water flooding. Although thermal methods are most commonly applied to recover viscous oil, they are impractical on ANS because of the concern of thawing the permafrost, which could cause disastrous environmental damage. Recently, low salinity water flooding (LSWF) has been considered to enhance oil recovery by reducing residual oil saturation in the Schrader Bluff viscous oil reservoir. In this study, lab experiments have been conducted to investigate the potential of LSWF to improve heavy oil recovery from the Schrader Bluff sand. Fresh-state core plugs cut from preserved core samples with original oil saturations have been flooded sequentially with high salinity water, low salinity water, and softened low salinity water. The cumulative oil production and pressure drops have been recorded, and the oil recovery factors and residual oil saturation after each flooding have been determined based on material balance. In addition, restored-state core plugs saturated with viscous oil have been employed to conduct unsteady-state displacement experiments to measure the oil-water relative permeabilities using high salinity water and low salinity water, respectively. The emulsification of provided viscous oil and low salinity water has also been investigated. Furthermore, the contact angles between the crude oil and reservoir rock have been measured. It has been found that the core plugs are very unconsolidated, with porosity and absolute permeability in the range of 33% to 36% and 155 mD to 330 mD, respectively. A produced crude oil sample having a viscosity of 63 cP at ambient conditions was used in the experiments. The total dissolved solids (TDS) of the high salinity water and the low salinity water are 28,000 mg/L and 2,940 mg/L, respectively. Softening had little effect on the TDS of the low salinity water, but the concentration of Ca2+ was reduced significantly. The residual oil saturations were reduced gradually by applying LSWF and softened LSWF successively after high salinity water flooding. On average, LSWF can improve viscous oil recovery by 6.3% OOIP over high salinity water flooding, while the softened LSWF further enhances the oil recovery by 1.3% OOIP. The pressure drops observed in the LSWF and softened LSWF demonstrate more fluctuation than that in the high salinity water flooding, which indicates potential clay migration in LSWF and softened LSWF. Furthermore, it was found that, regardless of the salinities, the calculated water relative permeabilities are much lower than the typical values in conventional systems, implying more complex reactions between the reservoir rock, viscous oil, and injected water. Mixing the provided viscous oil and low salinity water generates stable water-in-oil (W/O) emulsions. The viscosities of the W/O emulsions made from water-oil ratios of 20:80 and 50:50 are higher than that of the provided viscous oil. Moreover, the contact angle between the crude oil and reservoir rock in the presence of low salinity water is larger than that in the presence of high salinity water, which may result from the wettability change of the reservoir rock by contact with the low salinity water.

Download or read book Mechanistic Studies for Improved Understanding of Low Salinity Waterflooding Based Enhanced Oil Recovery and Potential Application to the Alaskan North Slope Reservoirs written by Mukul N. Chavan and published by . This book was released on 2015 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improvement in the recovery of oil by low or reduced salinity water has been reported by many researchers. However, a consistent mechanistic explanation behind low salinity waterflood has not yet emerged. A thorough literature review was conducted that pertains to low salinity water based enhanced oil recovery and preliminary screening criteria were proposed which may help in narrowing down the responsible mechanisms and identifying suitable candidates for low salinity waterflood. Altogether nine different variables, such as clays, oil characteristics, salinity ranges etc. were considered in developing the screening criteria. With the exception of some tests on standard Berea sandstone cores, all other experimental studies were carried out on representative Alaska North Slope (ANS) reservoir core samples and oil and brine samples. Experimental studies involved a direct visualization of the release of crude oil from the clay surface with low salinity waterflood as observed through a simple substrate type test. Amott type spontaneous displacement tests were performed to quantitatively determine the effect of low salinity water using core materials containing different types of clays. Two sets of low salinity water coreflooding experiments were conducted in the tertiary recovery mode; first using dead oil and the second using recombined oil at pseudo reservoir conditions to examine the potential in improving oil recovery. Oil recoveries were also compared with continuous injection vs slug-wise injection of low salinity water. Finally, surface level investigation was performed using an optical microscope to visually analyze the impact of low salinity water on core samples. All the experiments performed with low salinity water on Alaska North Slope (ANS) reservoir core samples consistently showed anywhere between a 3-30 % increase in oil production with the use of low salinity brine. The literature review identified wettability alteration, cation exchange capacity, clay type and clay content as some of the dominant mechanisms influencing low salinity waterflooding.

Download or read book Experimental Investigation of Nonthermal Enhanced Oil Recovery Techniques for Improving Oil Recovery on Alaska North Slope written by and published by . This book was released on 2022 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exploitation of viscous and heavy oils on Alaska North Slope (ANS) requires nonthermal enhanced oil recovery (EOR) techniques. Currently, three nonthermal EOR methods, including solvent injection, low salinity water (LSW) flooding, and low salinity polymer (LSP) injection, have been proved to be useful on ANS. ANS viscous and heavy oils can be developed effectively by combining those three nonthermal EOR techniques. In this dissertation, lab experiments have been conducted to investigate the potential of the proposed hybrid nonthermal EOR techniques, including HSW (high salinity water)-LSW-softened LSW flooding, HSW-LSW-LSP flooding, CO2-enriched LHS (light hydrocarbon solvent)-alternating-LSW flooding, LHS-alternating-LSW flooding, CO2-enriched LHS (light hydrocarbon solvent)-alternating-LSP flooding, and LHS-alternating-LSP flooding, to improve ANS viscous oil recovery. Besides, the effect of essential clay minerals, including sodium-based montmorillonite (Na-Mt), calcium-based montmorillonite (Ca-Mt), illite, and kaolinite, on LSW flooding has been examined. In addition, the CO2 influence on solvent-alternating-LSP flooding in enhancing ANS viscous oil recovery has been investigated. Furthermore, the blockage issue during CO2-enriched LHS-alternating-LSP flooding has been investigated, and its solution has been proposed and analyzed. The EOR potential of the proposed hybrid EOR techniques has been evaluated by conducting coreflooding experiments. Additionally, relative permeability, swelling property, zeta potential, interfacial tension (IFT), and pressure-volume-temperature (PVT) tests have been conducted to reveal the EOR mechanisms of the proposed hybrid EOR techniques. Moreover, water ion analysis of DI-water/natural-sand and DI-water/natural-sand/CO2 systems has been carried out to reveal the complex reaction between CO2, sand, and LSP solution. It was found that, compared to conventional waterflooding, all the proposed hybrid EOR techniques could result in better oil recovery potential. It was noticed that the presence of CO2 in LHS could be more beneficial to the solvent-alternating-LSW/LSP flooding processes during the 1st cycle due to the greater effectiveness of oil viscosity reduction. In particular, severe blockage issue occurred when conducting CO2-enriched LHS-alternating-LSP flooding using sand pack due to the polymer precipitation. Additionally, the calculated water relative permeabilities are much lower than the typical values, implying more complex interactions between the reservoir rock, heavy oil, and injected water. Moreover, comparing to HSW, LSW could further swell Na-Mt significantly, which may benefit LSW flooding by improving sweep efficiency since in-situ swelling of Na-Mt has the potential to block the higher permeable water-flooded zone and divert the injected brine to lower permeable and unswept area. Comparing to Na-Mt, LSW couldn’t swell Ca-Mt and illite further, whereas kaolinite was incapable of swelling in both HSW and LSW. Furthermore, about 60 mole% of solvent could be dissolved into the ANS viscous oil at target reservoir condition, resulting in oil swelling and viscosity reduction effects, which provided better microscopic displacement efficiency. Although the presence of CO2 in LHS had a negative impact on the oil swelling effect, the influence on the oil viscosity reduction was positive. In addition, reducing the salinity of water could generate more negative zeta potential values on the surface of clay minerals and sand, making it more water wet. Besides, IFT of oil/LSW system is higher than that of oil/HSW system, indicating that IFT reduction is not an EOR mechanism of LSW flooding in our proposed hybrid EOR techniques. Additionally, after introducing CO2 to the DIwater/natural-sand system, the concentration of multivalent cations was increased, which may be responsible for the polymer precipitation. The blockage issue could be solved by injecting LSW as a spacer between CO2-enriched LHS injection and LSP injection.

Download or read book Low Salinity Water Alternate Gas Injection Process for Alaskan Viscous Oil EOR written by Kushagra Saxena and published by . This book was released on 2017 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide has excellent oil swelling and viscosity reducing characteristics. CO2 injection alternated with water has shown substantial incremental recovery over waterflood for the Alaska North Slope (ANS) viscous oil reservoirs. However, for any project, the ultimate CO2 slug size is finite and once the apportioned solvent volume is used up, the reservoir oil rates gradually revert to the low waterflood rates during the later life of a field. Low salinity waterflooding (LSWF) has also shown some promise based on corefloods and single well tracer tests in North Slope light oil reservoirs. However, two challenges impede its implementation as a standalone enhanced oil recovery (EOR) option on the North Slope: 1) slow response; the delay prolonged with increasing oil viscosity and 2) large upfront investments for the processing and transport of source water. This study proposes a hybrid EOR scheme, the low salinity water alternate gas (LSWAG) process, for the viscous fields of the ANS. The process was modeled by coupling geochemical and ion exchange reactions to a CO2-WAG type pattern model of the Schrader Bluff O sand. The Schrader Bluff reservoir has been classified suitable for low salinity EOR based on its permeability, temperature, clay content, and oil and formation water properties. Oil recovery through wettability alteration was modeled through ion exchange at the clay sites. Multiphase compositional flow simulation was run using numerical dispersion control. LSWAG forecast for 50 years following 36 years of high salinity waterflood recovered 15% OOIP more oil over high salinity waterflood and 4% incremental over high salinity WAG. This translates to an improvement of 58% and 11% over waterflood and conventional WAG respectively. Higher oil rates were observed during later life due to increased oil relative permeability caused by the low salinity mechanism. Furthermore, very low solvent utilization values were seen for LSWAG which can be tied to the higher ultimate oil recovery potential of using low salinity water over conventional waterflood. In summary, LSWAG outperformed LSWF and conventional WAG by synthesizing the oil swelling and viscosity reduction advantages of CO2 with lower residual oil benefits of LSWF, while overcoming the challenges of the late response of LSWF and low waterflood oil rates during later life in a conventional WAG flood.

Download or read book Low Salinity Cyclic Water Injection for Enhanced Oil Recovery in Alaska North Slope written by Sathish S. Kulathu and published by . This book was released on 2009 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Properties and flow pattern of injected water have an impact on properties like rock wettability and oil saturation. Researchers have observed increased oil recovery with low salinity brines and reduced water production with cyclic injection. Low salinity cyclic water injection is an interesting combination to be evaluated for further implementation. Two-phase water-oil flow experiments were conducted on cleaned and oil-aged sandstone cores in a core holder apparatus. At connate water saturation, modified Amott-Harvey tests were performed to study wettability. Cyclic waterfloods were conducted to recover oil. Residual oil saturation (Sor) was calculated after every step. The experiments were repeated with reconstituted brines of different salinity and Alaska North Slope (ANS) lake water. The effect of low salinity waterfloods and oil-aging on wettability alteration was studied. The results were compared with available data from conventional floods performed on the same cores. Cyclic floods were also tested for different pulse intervals. Conventional waterflooding was conducted on recombined oil-saturated cores at reservoir conditions. Faster reduction in Sor and additional oil recovery was observed consistently with low salinity cyclic injection. Oil-aging reduced water wetness of cores. Subsequent low salinity floods restored the water wetness marginally. Shorter pulses yielded better results than longer intervals"--Leaf iii.

Download or read book Reservoir Simulation Study on Schrader Bluff Polymer Flood written by Yirong Jiang and published by . This book was released on 2009 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The objective of this research project was to study the benefit of polymer flood in the Schrader Bluff reservoir on the North Slope of Alaska. This multi-billion-barrel reservoir has been water flooded for 11 years. Due to the unfavorable mobility ratio, the expected ultimate recovery factor for water flood is low, opening up great opportunities for enhanced oil recovery (EOR). Polymer flood is expected to improve the unfavorable water/oil mobility ratio which has lead to unstable displacement and poor sweep efficiency currently being observed in the reservoir. To determine if polymer flood would enhance oil recovery in the Schrader Bluff reservoir, related publications were reviewed. A fine grid reservoir simulation model was constructed and history- matched. This reservoir model was then used to evaluate polymer flood in the Schrader Bluff reservoir. Parameters expected to impact the polymer flood performance were also investigated, including polymer viscosity, shear rate and injection timing. This study concluded that polymer flood could be an effective EOR process in the Schrader Bluff viscous oil reservoir"--Leaf iii.

Download or read book DEVELOPMENT OF SHALLOW VISCOUS OIL RESERVES IN NORTH SLOPE written by and published by . This book was released on 2004 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: North Slope of Alaska has huge oil deposits in heavy oil reservoirs such as Ugnu, West Sak and Shrader Bluff etc. The viscosity of the last two reservoir oils vary from (almost equal to)30 cp to (almost equal to)3000 cp and the amount in the range of 10-20 billion barrels. High oil viscosity and low formation strength impose problems to high recovery and well productivity. Water-alternate-gas injection processes can be effective for the lower viscosity end of these deposits in West Sak and Shrader Bluff. Several gas streams are available in the North Slope containing NGL and CO2 (a greenhouse gas). The goal of this research is to develop tools to find optimum solvent, injection schedule and well-architecture for a WAG process in North Slope shallow sand viscous oil reservoirs. Coreflood, quarter 5-spot study, compositional simulation, wettability, relative permeability study and streamline-based simulation were conducted in this project. 1D compositional simulation results agree reasonably well with those of the slim tube experiments. Injection of CO2-NGL is preferable over that of PBG-NGL. MME is sensitive to pressure (in the range of 1300-1800 psi) for the injection of PBG-NGL, but not for CO2-NGL. Three hydrocarbon phases form in this pressure range. As the mean thickness of the adsorbed organic layer on minerals increases, the oil-water contact angle increases. The adsorbed organic films left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion for minerals aged with just the asphaltene fraction is similar to that of the whole oil implying that asphaltenes are responsible for the mixed-wettability in this reservoir. A new relative permeability model for a four-phase, mixed-wet system has been proposed. A streamline module is developed which can be incorporated in an existing finite-difference based compositional simulator to model water flood, gas flood and WAG flood. Horizontal wells increase well deliverability over vertical wells, but sweep efficiency can decrease. The well performance depends on the well length, position, heterogeneity, and viscosity ratio. The productivity increase due to electromagnetic heating is a function of power intensity, flow rate, and frequency etc. The productivity of a well can be doubled by electromagnetic heating. A high-pressure quarter 5-spot model has been constructed to evaluate the sweep efficiency of miscible WAG floods. WAG displacement reduces bypassing compared to gas floods and improves oil recovery in cores. As the WAG ratio decreased and slug size increased, oil recovery increased. Oil was recovered faster with increased slug size and decreased WAG ratio in the simulations for field cases studied.

Download or read book Technical and Economic Evaluation of the First Ever Polymer Flood Field Pilot to Enhance the Recovery of Heavy Oils on Alaska s North Slope Via Machine Assisted Reservoir Simulation written by Cody D. Keith and published by . This book was released on 2022 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer flooding has become globally established as a potential enhanced oil recovery method for heavy oils. To determine whether this technology may be useful in developing the substantial heavy oil resources on the Alaska North Slope, a polymer flood field pilot commenced at the Milne Point Unit in August 2018. This study seeks to evaluate the results of the field pilot on a technical and economic basis. A reservoir simulation model is constructed and calibrated to predict the oil recovery performance of the pilot through machine-assisted reservoir simulation techniques. To replicate the early water breakthrough observed during waterflooding, transmissibility contrasts are introduced into the simulation model, forcing viscous fingering effects. In the ensuing polymer flood, these transmissibility contrasts are reduced to replicate the restoration of injection conformance during polymer flooding. Transmissibility contrasts are later reinstated to replicate fracture overextension interpreted in one of the producing wells. The calibrated simulation models produced at each stage of the history matching process are used to forecast oil recovery. These forecasts are used as input for economic analysis, incremental to waterflooding expectations. The simulation forecasts indicate that polymer flooding significantly increases the heavy oil production for this field pilot compared to waterflooding alone, yielding attractive project economics. However, meaningful variations between simulation scenarios demonstrate that a simulation model is only valid for prediction if flow behavior in the reservoir remains consistent with that observed during the history matched period. Critically, this means that a simulation model calibrated for waterflooding may not fully capture the technical and economic benefits of an enhanced oil recovery process such as polymer flooding. Subsequently, the simulation model and economic model are used in conjunction to conduct a sensitivity analysis for polymer flood design parameters, from which recommendations are provided for both the continued operation of the current field pilot and future polymer flood designs. The results demonstrate that a higher polymer concentration can be injected due to the development of fractures in the reservoir. The throughput rate should remain high without exceeding operating constraints. A calculated point-forward polymer utilization parameter demonstrates the decreasing efficiency of the polymer flood at later times in the pattern life. Future projects will benefit from starting polymer injection earlier in the pattern life. A pattern with tighter horizontal well spacing will observe a greater incremental benefit from polymer flooding.

Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Miscible Enhanced Oil Recovery Studies for Schrader Bluff Heavy Oil Reservoir North Slope of Alaska written by Maruti S. Inaganti and published by . This book was released on 1994 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phase Behavior Solid Organic Precipitation and Mobility Characterization Studies in Support of Enhanced Heavy Oil Recovery on the Alaska North Slope written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The medium-heavy oil (viscous oil) resources in the Alaska North Slope are estimated at 20 to 25 billion barrels. These oils are viscous, flow sluggishly in the formations, and are difficult to recover. Recovery of this viscous oil requires carefully designed enhanced oil recovery processes. Success of these recovery processes is critically dependent on accurate knowledge of the phase behavior and fluid properties, especially viscosity, of these oils under variety of pressure and temperature conditions. This project focused on predicting phase behavior and viscosity of viscous oils using equations of state and semi-empirical correlations. An experimental study was conducted to quantify the phase behavior and physical properties of viscous oils from the Alaska North Slope oil field. The oil samples were compositionally characterized by the simulated distillation technique. Constant composition expansion and differential liberation tests were conducted on viscous oil samples. Experiment results for phase behavior and reservoir fluid properties were used to tune the Peng-Robinson equation of state and predict the phase behavior accurately. A comprehensive literature search was carried out to compile available compositional viscosity models and their modifications, for application to heavy or viscous oils. With the help of meticulously amassed new medium-heavy oil viscosity data from experiments, a comparative study was conducted to evaluate the potential of various models. The widely used corresponding state viscosity model predictions deteriorate when applied to heavy oil systems. Hence, a semi-empirical approach (the Lindeloff model) was adopted for modeling the viscosity behavior. Based on the analysis, appropriate adjustments have been suggested: the major one is the division of the pressure-viscosity profile into three distinct regions. New modifications have improved the overall fit, including the saturated viscosities at low pressures. However, with the limited amount of geographically diverse data, it is not possible to develop a comprehensive predictive model. Based on the comprehensive phase behavior analysis of Alaska North Slope crude oil, a reservoir simulation study was carried out to evaluate the performance of a gas injection enhanced oil recovery technique for the West Sak reservoir. It was found that a definite increase in viscous oil production can be obtained by selecting the proper injectant gas and by optimizing reservoir operating parameters. A comparative analysis is provided, which helps in the decision-making process.

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alkali surfactant polymer ASP Flooding Potential and Simulation for Alaskan North Slope Reservoir written by Tejas S. Ghorpade and published by . This book was released on 2014 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhanced oil recovery (EOR) is essential to recover bypassed oil and improve recovery factor. Alkaline-surfactant-polymer (ASP) flooding is a chemical EOR method that can be used to recover heavy oil containing organic acids from sandstone formations. It involves injection of alkali to generate in situ surfactants, improve sweep efficiency, and reduce interfacial tension (IFT) between displacing and displaced phase, and injection of a polymer to improve mobility ratio; typically, it is followed by extended waterflooding. The concentration of alkali, surfactant, and polymer used in the process depends on oil type, salinity of solution, pressure, temperature of the reservoir, and injection water quality. This project evaluates the effect of waterflooding on recovery, calculates the recovery factor for ASP flooding, and optimum concentration of alkali, surfactant, and polymer for an Alaskan reservoir. Also, the effects of waterflooding and improvement with ASP flooding are evaluated and compared. Studies of these effects on oil recovery were analyzed with a Computer Modeling Group (CMG)-generated model for the Alaskan North Slope (ANS) reservoir. Based on a literature review and screening criteria, the Western North Slope (WNS) 1 reservoir was selected for the ASP process. A CMG - WinProp simulator was used to create a fluid model and regression was carried out with the help of actual field data. The CMG - WinProp model was prepared with a 5 spot well injection pattern using the CMG STARS simulator. Simulation runs conducted for primary and waterflooding processes showed that the recovery factor increased from 3% due to primary recovery to 45% due to waterflooding at 500 psi drawdown for 60 years with a constant producing gas oil ratio (GOR). ASP flooding was conducted to increase recovery further, and optimum ASP parameters were calculated for maximum recovery. Also, effect of alkali, surfactant and polymer on recovery was observed and compared with ASP flood. If proved effective, the use of ASP chemicals for ANS reservoirs to increase the recovery factor could replace current miscible gas injection with chemical EOR. It will help to develop chemical flooding processes for heavier crude oil produced in harsh environments and create new horizons for chemical industries in Alaska.

Download or read book Laboratory Investigation of Mechanisms Governing Low salinity Waterflooding in Oil wet Carbonate Reservoirs written by Gregory Kojadinovich and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved oil recovery via wettability alteration by tuning the ionic composition of the injection water has been thoroughly researched in recent years. It has been well documented that seawater can increase the water wetness of chalk at high temperature. Forced displacement and spontaneous imbibition experiments have attributed the wettability alteration to interactions between active ions in the brine, Ca2+, Mg2+, and SO42-, the rock surface, and the oil phase. It has been suggested that the adsorption of SO42- onto the rock surface causes the bond between adsorbed carboxylic material in the crude oil and the rock surface to deteriorate which causes the release of the crude oil. Reduction in ionic strength of the injection water has also been proposed to trigger the effect of wettability alteration in carbonates. Although the numerous experiments devoted to understanding the mechanisms governing the low salinity effect in the past two decades, there has been no consensus about the dominant mechanisms driving wettability alteration. The purpose of this research is to improve the understanding of how reduced ionic strength and potentially determining ions (PDIs) contribute to oil recovery, as well as provide a direct comparison of their oil recovery performance for a synthetic oil versus crude oil during waterflooding. For this, a series of waterflood experiments were conducted in the laboratory at 90 C in Indiana limestone core plugs. Chemically tuned brines derived from seawater were used in secondary and tertiary recovery modes to displace synthetic oil. A waterflood with formation brine was also conducted as an experimental baseline to assess the advantages of low-salinity waterflooding over typical secondary recovery methods. Effluent analysis was conducted to evaluate the surface interactions occurring between the brine and rock surface. Gas chromatography-mass spectroscopy was performed to compare the chemical make-up of the synthetic and crude oil. Oil recovery curves from this study indicate that there was no benefit afterincreasing the concentration of PDIs in injection water compared to seawater (SW). However, the use of seawater and all chemically tuned brines derived from seawater resulted in an average 6.47% increase in oil recovery post water breakthrough, relative to the formation brine waterflood. The success of wettability alteration leading to improved oil recovery in carbonates has been noted as a strong function of the oil composition.

Download or read book History Matching and Prediction of a Polymer Flood Pilot in Heavy Oil Reservoir on Alaska North Slope written by 王新丹 and published by . This book was released on 2021 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first-ever polymer flood pilot to enhance heavy oil recovery on Alaska North Slope is ongoing. After more than 3 years of polymer injection, significant benefit has been observed from the decrease in water cut from 65% to less than 15% in the project producers. The primary objective of this study is to develop a robust history-matched reservoir simulation model capable of predicting future polymer flood performance. In this work, the reservoir simulation model has been developed based on the geological model and available reservoir and fluid data. In particular, four high transmissibility strips were introduced to connect the injector-producer well pairs, simulating short-circuiting flow behavior that can be explained by viscous fingering and reproducing the water cut history. The strip transmissibilities were manually tuned to improve the history matching results during the waterflooding and polymer flooding periods, respectively. It has been found that higher strip transmissibilities match the sharp water cut increase very well in the waterflooding period. Then the strip transmissibilities need to be reduced with time to match the significant water cut reduction. The viscous fingering effect in the reservoir during waterflooding and the restoration of injection conformance during polymer flooding have been effectively represented. Based on the validated simulation model, numerical simulation tests have been conducted to investigate the oil recovery performance under different development strategies, with consideration for sensitivity to polymer parameter uncertainties. The oil recovery factor with polymer flooding can reach about 39% in 30 years, twice as much as forecasted with continued waterflooding. Besides, the updated reservoir model has been successfully employed to forecast polymer utilization, a valuable parameter to evaluate the pilot test's economic efficiency. All the investigated development strategies indicate polymer utilization lower than 3.5 lbs/bbl in 30 years, which is less than that of the same polymer used in a polymer pilot in Argentina.

Download or read book Oil Recovery Increases by Low Salinity Flooding written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Waterflooding is by far the most widely used method in the world to increase oil recovery. Historically, little consideration has been given in reservoir engineering practice to the effect of injection brine composition on waterflood displacement efficiency or to the possibility of increased oil recovery through manipulation of the composition of the injected water. However, recent work has shown that oil recovery can be significantly increased by modifying the injection brine chemistry or by injecting diluted or low salinity brine. This paper reports on laboratory work done to increase the understanding of improved oil recovery by waterflooding with low salinity injection water. Porous media used in the studies included outcrop Berea sandstone (Ohio, U.S.A.) and reservoir cores from the Green River formation of the Uinta basin (Utah, U.S.A.). Crude oils used in the experimental protocols were taken from the Minnelusa formation of the Powder River basin (Wyoming, U.S.A.) and from the Green River formation, Monument Butte field in the Uinta basin. Laboratory corefloods using Berea sandstone, Minnelusa crude oil, and simulated Minnelusa formation water found a significant relationship between the temperature at which the oil- and water-saturated cores were aged and the oil recovery resulting from low salinity waterflooding. Lower aging temperatures resulted in very little to no additional oil recovery, while cores aged at higher temperatures resulted in significantly higher recoveries from dilute-water floods. Waterflood studies using reservoir cores and fluids from the Green River formation of the Monument Butte field also showed significantly higher oil recoveries from low salinity waterfloods with cores flooded with fresher water recovering 12.4% more oil on average than those flooded with undiluted formation brine.

Download or read book Review and Experimental Studies to Evaluate the Impact of Salinity and Wettability on Oil Recovery Efficiency written by Chinedu C. Agbalaka and published by . This book was released on 2006 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Oil recovery efficiency is influenced by a myriad of interacting variables such as pore geometry, wettability, rock mineralogy, brine salinity, oil composition, etc. Reservoir wettability is known to have very significant influence on pore scale displacement and hence is a strong determinant of the final residual oil saturation. Recent studies have indicated the improved oil recovery potential of low salinity brine injection. Though the reason for this reported increase is still unclear, it is speculated that it may be due to wettability changes. In this work, coreflood studies were carried out to determine the recovery benefits of low salinity waterflood over high salinity waterflood and the role of wettability in any observed recovery benefit. Two sets of coreflood experiments were conducted; the first set examined the EOR potential of low salinity floods in tertiary oil recovery processes while the second set examined the secondary oil recovery potential of low salinity floods. Changes in residual oil saturation with variation in wettability and brine salinity were monitored. All the coreflood tests consistently showed an increase in produced oil and water-wetness with decrease in brine salinity and increase in brine temperature"--Leaf iii.