High-water-cut mature reservoirs typically serve as the“ballast”for ensuring China’s annual crude oil production of 200 million tons.Despite the use of water flooding and chemical methods,over 40%of crude oil remai...High-water-cut mature reservoirs typically serve as the“ballast”for ensuring China’s annual crude oil production of 200 million tons.Despite the use of water flooding and chemical methods,over 40%of crude oil remains unexploited.It is critical to develop efficient revolutionary technologies to further enhance oil recovery(EOR)by a large percentage in high-water-cut mature reservoirs.To address this issue,the potential of vertical remaining oil in Daqing Oilfield is first analyzed from massive monitoring data.Using molecular dynamics simulation to design optimal synthetic routine,a copolymer without flu-orine or silicon is synthesized by modifying vinyl acetate(VAc)with maleic anhydride(MA)and styrene(St),and treated as a supercritical CO_(2)(scCO_(2))thickener.The underlying EOR mechanism of the scCO_(2) thickener is thereafter clarified by high-temperature,high-pressure oil displacement experiments.The EOR effect by thickened scCO_(2) flooding in a typical high-water-cut mature reservoir is predicted,and future technological advancements of the technique are ultimately discussed.Results show that the ver-tical remaining oil enriched in weakly swept zones is a primary target for further EOR in high-water-cut mature reservoirs.The copolymer typically exhibits good solubility,strong dispersion stability,and high thickening effect in scCO_(2).Under an ambient pressure of 10 MPa and a temperature of 50℃,the disso-lution of copolymer at a mass concentration of 0.2%can effectively increase the viscosity of scCO_(2) by 39.4 times.Due to the synergistic effect between expanding vertical swept volume and inhibiting gas channel-ing,crude oil recovery can be further enhanced by 23.1%for a typical high-water-cut mature reservoir when the scCO_(2) viscosity is increased by 50 times.Our understandings demonstrate that the thickened scCO_(2) flooding technology has significant technical advantages in high-water-cut mature reservoirs,with challenges and future development directions in field-scale applications also highlighted.展开更多
This paper describes a simple, easy process for screening microorganisms, and introduces a laboratory simulation device and process of microbial enhanced oil recovery (MEOR) , which is a necessary research step for t...This paper describes a simple, easy process for screening microorganisms, and introduces a laboratory simulation device and process of microbial enhanced oil recovery (MEOR) , which is a necessary research step for trial in oilfields. The MEOR mechanism and the influence of adsorption, diffusion, metabolism, nutrition, porosity, and permeability are analyzed. The research indicates that different microbes have different efficiencies in EOR and that different culture types play different roles in EOR. The effect of syrup is better than that of glucose, and larger porosity is favorable to the reproduction and growth of microbes, thereby improving the oil recovery. Using crude oil as a single carbon source is more appreciable because of the decrease in cost of oil recovery. At the end of this paper, the development of polymerase chain reaction (PCR) for the future is discussed.展开更多
The compound system of polyacrylamide hydrogels and surfactant solutions are used for enhanced oil recovery(EOR).The polyacrylamide hydrogels are injected into block high-permeability zones firstly,followed by a low-c...The compound system of polyacrylamide hydrogels and surfactant solutions are used for enhanced oil recovery(EOR).The polyacrylamide hydrogels are injected into block high-permeability zones firstly,followed by a low-cost sacrificial agent,then an oil-displacing surfactant,and finally an aqueous polymer solution containing diethanolamine,to enhance oil production.The hydrogels are selected through oscillatory rheometry,while the surfactant is optimized after optical imaging analysis.The EOR performance of the compound system is evaluated through core flooding experiments and reservoir numerical simulation.Specifically,the properly cross-linked polyacrylamide hydrogel can be selected using its elastic modulus as a quantitative parameter while accounting for pore structure.The sacrificial agent is used to block active adsorption sites in the rock matrix before mobilizing more crude oil with a nonionic-anionic surfactant system.The addition of the mild organic alkali(diethanolamine)into the polymer slug reduces surfactant adsorption and improves sweep efficiency,thereby enhancing the oil-washing effect.Flooding experimental results show that the sequential injection of hydrogel and surfactant compositions prolongs the period of increasing pressure gradient during subsequent waterflooding and significantly boosts oil production,achieving a 21-percentage-point increase in oil displacement efficiency.Numerical simulation for the target reservoir in the West Siberian oil province confirms the effectiveness,projecting a maximum cumulative oil increase of 6851 t over three years.展开更多
Nanoparticles are increasingly used in chemical enhanced oil recovery(CEOR)due to their ability to improve oil recovery by altering reservoir rock and fluid properties.These nanoparticles,which have unique physical an...Nanoparticles are increasingly used in chemical enhanced oil recovery(CEOR)due to their ability to improve oil recovery by altering reservoir rock and fluid properties.These nanoparticles,which have unique physical and chemical traits,can be synthesized chemically or biologically.Biological synthesis,involving fungi,bacteria,algae,yeast,or plant materials are more stable,efficient,cost-effective,and environmentally friendly.With rising global energy demand and a shift towards greener solutions,the focus has moved from hazardous chemical synthesis to green synthesis for CEOR.Although some research exists on green nanoparticles for oil recovery,a comprehensive review of these studies and the mechanisms(such as wettability alteration,interfacial tension reduction,and stability enhancement)is needed.This paper reviews recent advances in the biosynthesis of nanoparticles and nanocomposites for oil recovery,highlighting successful examples like SiO_(2)/Montmorillonite/Xanthan and Fe3O4/SiO_(2)/Xanthan,which improved recovery by altering wettability,reducing interfacial tension,and enhancing dispersion and thermal stability.The study also notes the preference for plant-based green synthesis over microbial synthesis due to complexity and cost.The findings provide insights into the impact of novel greenly synthesized nanoparticles in CEOR.展开更多
The displacement of residual crude oil and enhanced oil recovery from reservoirs of mature oil fields are challenging worldwide and have received intensive attentions in oil and gas industry.In this work,a novel metho...The displacement of residual crude oil and enhanced oil recovery from reservoirs of mature oil fields are challenging worldwide and have received intensive attentions in oil and gas industry.In this work,a novel method for enhanced oil recovery by displacement of oil with bionanofluids was proposed.Microdisplacement hydrodynamics of crude oil in microchannel sand-packed porous media by the bionanofluid were investigated by high-speed imaging.The machine learning models with the extreme gradient boosting(XGBoost) algorithm was developed for the prediction of residual oil saturation during the micro-displacement processes.The residual oil droplets within the porous media after the waterflooding were effectively removed through bionanofluid-flooding,resulting in additional enhanced oil recovery of 39.0%,which is double the recovery achieved by waterflooding at the same displacement velocity.By wavelet-transform image enhancement and the XGBoost algorithm in the machine learning,the residual oil saturations along the porous media were predicted accurately with the mean squared errors of 0.0045 and 0.0030 in the waterflooding and the bionanofluid-flooding,respectively.The results indicated that the machine learning is effective in characterizing the displacement behaviors and the bionanofluid-flooding could be an interesting approach,and thus has potential applications in enhanced oil recovery of waterflooding reservoirs.展开更多
The present study evaluated commercial starch behavior and tapioca starch nanoparticles(TSNP) with100 ppm ultralow salinity formation water as a potential alternative for enhanced oil recovery(EOR).Generally, starch e...The present study evaluated commercial starch behavior and tapioca starch nanoparticles(TSNP) with100 ppm ultralow salinity formation water as a potential alternative for enhanced oil recovery(EOR).Generally, starch exhibits excellent properties as a conventional viscosifier substitute in the petroleum industry. This study proposed a conventional polymer substitute, which is typically hydrolyzed polyacrylamide(HPAM) or oxide nanoparticles, for chemical flooding EOR employment. The TSNP was successfully synthesized via nanoprecipitation with ethanol as the precipitant medium. Two TSNP of different sizes, 1% and 3%, are successfully synthesized, which demonstrated chemical and physical attributes almost identical to raw tapioca starch(TS), corroborating their composition similarities. The 1%TSNP was significantly smaller compared to the 3% TSNP, but both samples possessed distinct angular,polygonal, and truncated shapes with sharp edges. Although the structure of the TSNP synthesized was a C-type crystal, their crystallinity was slightly lower. Fourier-transform infrared(FTIR) and energy dispersive X-ray(EDX) analyses confirmed similar chemical compositions of the raw TS and TSNP assessed. The EOR formulations employed in the study were prepared with various TS and TSNP concentrations, ranging from 0 ppm to 2000 ppm. The formulations were assessed at various temperatures between 25°C and 75°C. Rheological results indicated that TS and TSNP formulations coupled with low salinity formation water yielded non-Newtonian shear thickening behavior with respect to starch types,concentrations, temperatures, and shear rates. The 1% TSNP formulation exhibited favorable solution viscosifying criteria than the 3% TSNP sample within evaluated parameters. Surface tension, IFT, and wettability alteration measurements revealed indirect and inconclusive trend regarding TSNP concentrations and temperatures. Nonetheless, adding 1% and 3% TSNP considerably influenced IFT reduction and wettability alteration in several favorable combinations, indicating feasibility for EOR applications.展开更多
Given that a large amount of crude oil remains on the surface of rocks and is difficult to produce after conventional waterflooding,a new superwetting oil displacement system incorporating the synergy between a hydrox...Given that a large amount of crude oil remains on the surface of rocks and is difficult to produce after conventional waterflooding,a new superwetting oil displacement system incorporating the synergy between a hydroxyl anion compound(1OH-1C)and an extended surfactant(S-C_(13)PO_(13)S)was designed.The interfacial tension,contact angle and emulsification performance of the system were measured.The oil displacement effects and improved oil recovery(IOR)mechanisms of 1OH-1C,S-C_(13)PO_(13)S and their compound system were investigated by microscopic visualization oil displacement experiments and core displacement experiments.The results show that 1OH-1C creates a superwetting interface and electrostatic separation pressure on the solid surface,which destroys the strong interactions between crude oil and quartz to peel off the oil film.S-C_(13)PO_(13)S has low interfacial tension,which can promote the flow of remaining oil and emulsify it into oil-in-water emulsions.The compound system of 1OH-1C and S-C_(13)PO_(13)S has both superwettability and low IFT,which can effectively improve oil recovery through a synergistic effect.The oil displacement experiment of low-permeability natural core shows that the compound solution can increase the oil recovery by 16.4 percentage points after waterflooding.This new high-efficiency system is promising for greatly improving oil recovery in low-permeability reservoirs.展开更多
Polymer-based enhanced oil recovery boosts production in depleted oil fields.However,harsh reservoir conditions,such as high salinity and temperature,often reduce its effectiveness.This study explores the use of a new...Polymer-based enhanced oil recovery boosts production in depleted oil fields.However,harsh reservoir conditions,such as high salinity and temperature,often reduce its effectiveness.This study explores the use of a new aqueous polymeric nanofluid to overcome these challenges.The polymer we evaluated was partially hydrolyzed polyacrylamide(HPAM)with 40%hydrolysis and a molecular weight of 10 MD.The objective of this investigation was to enhance the efficacy of HPAM by incorporating multiwalled carbon nanotubes functionalized with COOH(MwCNT-COOH).Various tests were conducted to evaluatethe polymeric nanofluid,including Fourier transform infrared spectroscopy for bonding detection,viscoelastic behavior analysis under static and dynamic shear rates,interfacial tension measurements using the spinning drop technique,and wettability alteration studies through contact angle measurements.The efficiency of the new nanofluid in enabling oil recovery was compared to that of conventional polymers through core flooding experiments.The optimized polymeric nanoparticle injection resulted in a 10%increase in recuperation.This suggests that polymeric nanofluids may be a plausible solution for enhancing oil recovery-a solution that could boost oil production in reservoirs.展开更多
Enhanced oil recovery(EOR)refers to themanymethodologies used to augment the volume of crude oil extracted froman oil reservoir.These approaches are used subsequent to the exhaustion of basic and secondary recovery me...Enhanced oil recovery(EOR)refers to themanymethodologies used to augment the volume of crude oil extracted froman oil reservoir.These approaches are used subsequent to the exhaustion of basic and secondary recovery methods.There are three primary categories of Enhanced Oil Recovery(EOR):thermal,gas injection,and chemical.Enhanced oil recovery methods may be costly and intricate;yet,they facilitate the extraction of supplementary oil that would otherwise remain in the reservoir.Enhanced Oil Recovery(EOR)may prolong the lifespan of an oil field and augment the total output from a specific field.The parameters influencing oil recovery are a significant problem in Enhanced Oil Recovery(EOR)systems,necessitating further examination of the components that impact them.This research examined the impact of permeability fluctuations on fluid dynamics inside a sandstone reservoir and presented a contemporary overview of the three phases of Enhanced Oil Recovery(EOR),including detailed explanations of the methodologies used and the processes facilitating oil recovery.The challenges faced with several common EOR mechanisms were identified,and solutions were suggested.Additionally,the modern trend of incorporating nanotechnology and its synergistic impacts on the stability and efficacy of conventional chemicals for enhanced oil recovery(EOR)was scrutinised and evaluated.Ultimately,laboratory results and field activities were examined.The study looked closely at hownanoparticlesmove through reservoirs and evaluated enhanced oil recovery(EOR),mobility ratio,and fluid displacement efficiency.This study offers comprehensive insights into the use of enhanced oil recovery techniques for sustainable energy generation.展开更多
In deep oil reservoir development,enhanced oil recovery(EOR)techniques encounter significant challenges under high-temperature and high-salinity conditions.Traditional profile-control agents often fail to maintain sta...In deep oil reservoir development,enhanced oil recovery(EOR)techniques encounter significant challenges under high-temperature and high-salinity conditions.Traditional profile-control agents often fail to maintain stable blocking under extreme conditions and exhibit poor resistance to high temperature and high salinity.This study develops a functionalized nanographite system(the MEGO system)with superior high-temperature dispersibility and thermosalinity-responsive capability through polyether amine(PEA)grafting and noncovalent interactions with disodium naphthalene sulfonate(DNS)molecules.The grafted PEA and DNS provide steric hindrance and electrostatic repulsion,enhancing thermal and salinity resistance.After ten days of aggregation,the MEGO system forms stable particle aggregates(55.51-61.80 lm)that are suitable for deep reservoir migration and profile control.Both experiments and simulations reveal that particle size variations are synergistically controlled by temperature and salt ions(Na^(+),Ca^(2+),and Mg^(2+)).Compared with monovalent ions,divalent ions promote nanographite aggregation more strongly through double-layer compression and bridging effects.In core displacement experiments,the MEGO system demonstrated superior performance in reservoirs with permeabilities ranging from 21.6 to 103 mD.The aggregates formed within the pore throats significantly enhanced flow resistance,expanded the sweep volume,and increased the overall oil recovery to 56.01%.This research indicates that the MEGO system holds excellent potential for EOR in deep oil reservoirs.展开更多
During oil displacement,surfactants often encounter challenges such as emulsion instability and channeling,which can compromise their efficiency.To address these issues,polymer microspheres were synthesized via revers...During oil displacement,surfactants often encounter challenges such as emulsion instability and channeling,which can compromise their efficiency.To address these issues,polymer microspheres were synthesized via reverse microemulsion polymerization using acrylamide,2-methyl-2-acrylamidopropane sulfonic acid,and stearyl methacrylate as monomers,with N,N-methylenebisacrylamide as the crosslinker.The microspheres were then combined with sodium alkyl alcohol polyoxyethylene ether carboxylate to enhance emulsion stability and expand the swept volume of surfactant.A stable reverse microemulsion system was prepared using the maximum water solubilization rate as the indicator,and microspheres were synthesized based on this system.The ability of the microspheres to enhance emulsion stability was systematically evaluated.The plugging performance and enhanced oil recovery(EOR)efficiency of the microsphere/surfactant composite system were assessed through core seepage and oil displacement experiments.The experimental results demonstrated that microspheres were successfully prepared in a water-in-oil reverse microemulsion system with a solubilization rate of 42%.The emulsion stability was evaluated under an oil-to-water ratio of 7:3,a temperature of 80℃,and a salinity of 44,592 mg/L,by manually shaking the test tube five times.It was observed that the complete phase separation time of the emulsion increased from 10 to 120 min after the addition of microspheres.Under different permeability conditions(100×10^(-3),300×10^(-3),500×10^(-3)μm^(2)),the recovery efficiency of the composite system increased by 4.5%,8.3%,and 4.8%,respectively,compared to a single surfactant system.The microspheres developed in this study enhanced emulsion stability and increased the swept volume of surfactant within the formation,significantly boosting its oil recovery efficiency.展开更多
Hydrogels are widely used in reservoir flow control to enhanced oil recovery.However,challenges such as environmental contamination from conventional crosslinkers,poor solubility of crosslinking agents,and short gelat...Hydrogels are widely used in reservoir flow control to enhanced oil recovery.However,challenges such as environmental contamination from conventional crosslinkers,poor solubility of crosslinking agents,and short gelation times under high-temperature conditions(e.g.,150℃)have hindered their practical application.Herein,we present the synthesis of amine-functionalized carbon quantum dots(NH_(2)-CQDs),which act as both a nano-crosslinker and a nano-reinforcing agent within hydrogel systems.The NH_(2)-CQDs-incorporated hydrogel can remain stability for 300 days under the conditions of a mineralization degree of 2.11×10^(4)mg/mL and 170℃,and has high tensile strength(371 kPa),good toughness(49.6 kJ/m^(3)),excellent viscoelasticity(G'=960 Pa,G"=460 Pa)and shear resistance.In addition,NH_(2)-CQDs adds many hydroxyl groups to the hydrogel,which can be attached to the surface of various substances.At the same time,micro-nano capsules containing NH_(2)-CQDs were formed by self-assembly of hydrophobic SiO_(2)on water droplets,the NH_(2)-CQDs solution is encapsulated in a capsule,and when stimulated by external conditions(temperature,pH,surfactant),the capsule releases the NH_(2)-CQDs solution,this method greatly delays the crosslinking time between polymer and crosslinker at high temperature.Under the condition of 170℃and pH=7,the gelation time of 10%hydrophobic SiO_(2)coated hydrogel is 44 times that of uncoated hydrogel,which can be effectively used for deep formation flow control,and CQD give hydrogels fluorescence properties that can be used for underground signal tracking.展开更多
This paper introduces a novel approach combining radial borehole fracturing with Water-Alternating-Gas(WAG)injection,enabling simultaneous WAG injection and shale oil production in a single vertical well.A numerical r...This paper introduces a novel approach combining radial borehole fracturing with Water-Alternating-Gas(WAG)injection,enabling simultaneous WAG injection and shale oil production in a single vertical well.A numerical reservoir model incorporating the modified exponential non-Darcy law,stress sensitivity,and diffusion is established.The spatial distribution of permeability reduction shows that stress sensitivity enhances the non-Darcy effect,with apparent permeability decreasing to 0-92.1%of the initial value,highlighting the importance of maintaining reservoir pressure.Continuous CO_(2) flooding leads to early gas breakthrough,while continuous water flooding has less displacement efficiency.A 30%water-to-gas injection time ratio improves oil production and delays gas breakthrough compared to continuous CO_(2) injection.Optimal conditions for effective recovery are identified as an initial production period of 100 d and a well vertical spacing of 30 m.This study compares the production capacity of WAG operations under radial borehole fracturing and horizontal well fracturing.When the number of wells is two for both cases,the production capacity of radial borehole fracturing is comparable to that of five-stage horizontal well fracturing,indicating that radial borehole fracturing can serve as an alternative or supplement to horizontal well fracturing when the reservoir volume is limited.This study offers a new method and theoretical basis for the efficient development of shale oil.展开更多
High-molecular-weight partially hydrolyzed polyacrylamide(HPAM)has extensively used in enhanced oil recovery(EOR)process;however,it suffers from poor injectivity into low-permeability oil reservoirs and compromised lo...High-molecular-weight partially hydrolyzed polyacrylamide(HPAM)has extensively used in enhanced oil recovery(EOR)process;however,it suffers from poor injectivity into low-permeability oil reservoirs and compromised long-term thermal stability under reservoir conditions.To address these challenges,a viscoelastic surfactant,3-(N-erucamidopropyl-N,N-dimethyl ammonium)betaine(EDAB),was developed and systematically compared with HPAM.Experimental results demonstrate that EDAB outperforms HPAM in thermal resilience,salt tolerance,and interfacial activity.Unlike HPAM's thermal thinning behavior,EDAB displays thermo-thickening properties,with viscosity rising from 225 to 366 mPa⋅s as temperature increases from 25 to 55℃.EDAB maintains 100% viscosity retention under 80 mg⋅L^(−1) Ca^(2+)or Mg^(2+),whereas HPAM experiences 46%viscosity loss under identical ionic conditions.Core-flooding tests conducted under simulated Daqing oil reservoir conditions indicate that EDAB achieves a 1.4%higher incremental oil recovery factor than HPAM with equal initial solution concentration.When HPAM was employed as a mobility control for pre-or post-flush,EDAB elevates the recovery factor by 13.9%over water flooding.These comparative analyses underscore the potential of EDAB as a thermally stable,salt-insensitive alternative to HPAM,offering an optimized chemical strategy for EOR in challenging reservoir environments.The findings provide empirical validation for surfactant-based solutions to address HPAM's operational constraints in low-permeability formations.展开更多
Carbon dioxide Enhanced Oil Recovery(CO_(2)-EOR)technology guarantees substantial underground CO_(2) sequestration while simultaneously boosting the production capacity of subsurface hydrocarbons(oil and gas).However,...Carbon dioxide Enhanced Oil Recovery(CO_(2)-EOR)technology guarantees substantial underground CO_(2) sequestration while simultaneously boosting the production capacity of subsurface hydrocarbons(oil and gas).However,unreasonable CO_(2)-EOR strategies,encompassing well placement and well control parameters,will lead to premature gas channeling in production wells,resulting in large amounts of CO_(2) escape without any beneficial effect.Due to the lack of prediction and optimization tools that integrate complex geological and engineering information for the widely used CO_(2)-EOR technology in promising industries,it is imperative to conduct thorough process simulations and optimization evaluations of CO_(2)-EOR technology.In this paper,a novel optimization workflow that couples the AST-GraphTrans-based proxy model(Attention-based Spatio-temporal Graph Transformer)and multi-objective optimization algorithm MOPSO(Multi-objective Particle Swarm Optimization)is established to optimize CO_(2)-EOR strategies.The workflow consists of two outstanding components.The AST-GraphTrans-based proxy model is utilized to forecast the dynamics of CO_(2) flooding and sequestration,which includes cumulative oil production,CO_(2) sequestration volume,and CO_(2) plume front.And the MOPSO algorithm is employed for achieving maximum oil production and maximum sequestration volume by coordinating well placement and well control parameters with the containment of gas channeling.By the collaborative coordination of the two aforementioned components,the AST-GraphTrans proxy-assisted optimization workflow overcomes the limitations of rapid optimization in CO_(2)-EOR technology,which cannot consider high-dimensional spatio-temporal information.The effectiveness of the proposed workflow is validated on a 2D synthetic model and a 3D field-scale reservoir model.The proposed workflow yields optimizations that lead to a significant increase in cumulative oil production by 87%and 49%,and CO_(2) sequestration volume enhancement by 78%and 50%across various reservoirs.These findings underscore the superior stability and generalization capabilities of the AST-GraphTrans proxy-assisted framework.The contribution of this study is to provide a more efficient prediction and optimization tool that maximizes CO_(2) sequestration and oil recovery while mitigating CO_(2) gas channeling,thereby ensuring cleaner oil production.展开更多
CO_(2)-enhanced oil recovery(CO_(2)-EOR)is an economically viable carbon capture,utilization,and storage(CCUS)technique that is widely practiced and greatly contributes to the achievement of carbon-neutral cities.Howe...CO_(2)-enhanced oil recovery(CO_(2)-EOR)is an economically viable carbon capture,utilization,and storage(CCUS)technique that is widely practiced and greatly contributes to the achievement of carbon-neutral cities.However,studies on CO_(2)-EOR source-sink matching involving different emission sources,different carbon capture rates,and stepwise CO_(2)pipeline construction are scarce.Considering four types of carbon sources,including coal-fired power,iron and steel,cement,and chemical plants,with different CO_(2)capture rates(85%,90%,95%,and 100%,respectively),and using a five-phased construction plan with a 25-year build-up period,we developed a method for quantifying carbon emissions from different sources,calculating the effective storage of carbon in CO_(2)-EOR and optimizing CO_(2)-EOR source-sink matching to reduce project costs.Using the Subei Basin in the Jiangsu Province,China,as a case study,we calculated the theoretical CO_(2)-EOR storage to be 1.7408×10^(8)t and the effective CO_(2)-EOR storage to be 0.435×10^(8)t.We analyzed the completion rate of transportation pipelines,the number of connected carbon sources,and the mass of CO_(2)stored,as well as the cost-effectiveness and sensitivity.Implementation of CO_(2)-EOR effectively reduced the total cost of source-sink matching in the five-stage 25-year construction approach.The reduction of CO_(2)capture rates had no effect on the value of oil repelling.The capture cost significantly affected the total cost of source-sink matching,and the impacts of the carbon sources on the total cost were in the order coal-fired power>iron and steel>cement>chemical plants.This study provides an innovative tool for evaluating the CO_(2)storage potential of CO_(2)-EOR and provides an important framework for implementing CO_(2)-EOR and planning CCUS projects in the Subei Basin and similar regions.展开更多
The tight-tuff heavy oil reservoir exhibits severe heterogeneity and is characterized by high density,high viscosity,and a high wax content,posing significant challenges for its development.While CO_(2)huffand-puff(H-...The tight-tuff heavy oil reservoir exhibits severe heterogeneity and is characterized by high density,high viscosity,and a high wax content,posing significant challenges for its development.While CO_(2)huffand-puff(H-n-P)enhances oil recovery,these reservoirs struggle with low displacement efficiency.This study proposes a method that combines CO_(2)with an oil-soluble viscosity reducer to improve displacement efficiency in the H-n-P process for tight-tuff heavy oil reservoirs.It also focuses on evaluating pore utilization limits and optimizing the injection strategy.Core samples and crude oil from the TH oilfield(a tight-tuff heavy oil reservoir)were used to conduct online NMR core flooding experiments,including depletion development,water,CO_(2),and HDC(CO_(2)combined with an oil-soluble viscosity reducer)H-n-P injection processes.A single-porosity model accurately reflecting its geological characteristics was developed using the GEM component simulator within the CMG numerical simulation software to investigate the optimized schemes and the enhanced oil recovery potential for a tight-tuff heavy oil reservoir in the TH oilfield.This model was utilized to evaluate the impact of various injection strategies on oilfield recovery efficiency.The study was designed and implemented with five distinct injection schemes.Results showed that oil was produced primarily from large and medium pores during the depletion stage,while water H-n-P,with CO_(2)H-n-P,first targeted macropores,then mesopores,and micropores.The lower pore utilization limit was 0.0267μm.In the HDC H-n-P process,most oil was recovered from water-flooded pores.Still,HDC's lower injection capacity increased the pore utilization limit to 0.03μm,making micropore recovery difficult.Experimental and modeling results suggest that the optimal develo p ment plan for the TH oilfield is one cycle of HDC H-n-P followed by two cycles of CO_(2)H-n-P.This strategy leverages HDC's ability to promote water and oil recovery in the early stage and mass transfer and extraction capacity of CO_(2)in later cycles.Additionally,the characteristics of CO_(2)and HDC H-n-P processes,pore utilization,and recoverable oil(at the pore scale)were evaluated.The results of this study are crucial for refining the reservoir development plan.展开更多
This paper describes the experience of Jilin oilfield trials for Microbial Enhanced Oil Recovery (MEOR). A new technique to identify microbes with DNA for MEOR has been established, and useful microbes selected f...This paper describes the experience of Jilin oilfield trials for Microbial Enhanced Oil Recovery (MEOR). A new technique to identify microbes with DNA for MEOR has been established, and useful microbes selected for use in field trials. Behaviors of bacteria activated in the reservoir, oil recovery and water cut, and the viscosity of crude oil produced through huff & puff testing and flooding with molasses-injection tests, have been investigated in situ. CJF-002, which produces biopolysaccharide, is the best among the microbes used for field trials, as it can use molasses as nutrient and produce a small quantity of CO2 and a mass of water-insoluble biopolymer. The metabolic behavior in the reservoir showed that CJF-002 had a good potentiality for MEOR.展开更多
India is currently producing crude oil from matured fields because of insufficient discoveries of new fields.Therefore,in order to control the energy crisis in India,enhanced oil recovery(EOR)techniques are required t...India is currently producing crude oil from matured fields because of insufficient discoveries of new fields.Therefore,in order to control the energy crisis in India,enhanced oil recovery(EOR)techniques are required to reduce the import of crude from the OPEC(Organization of the Petroleum Exporting Countries).This review mentions chemical EOR techniques(polymers,surfactants,alkali,nanoparticles,and combined alkali-surfactant-polymer flooding)and operations in India.Chemical EOR methods are one of the most efficient methods for oil displacement.The efficiency is enhanced by interfacial tension(IFT)reduction using surfactants and alkali,and mobility control of injected water is done by adding a polymer to increase the volumetric sweep efficiency.This paper also reviews the current trend of chemical EOR,prospects of chemical EOR in Indian oilfields,the development of chemical EOR in India with their challenges raising with economics,and screening criteria for chemical EOR implementation on the field scale.Furthermore,the review gives a brief idea about chemical EOR implementation in Indian oilfields in future prospects to increase the additional oil recovery from existing depleted fields to reduce the import of crude oil.The outcome of this review depicts all chemical EOR operations and recovery rates both at the laboratory scale and field scale around the country.The additional recovery rates are compared from various chemical EOR methods like conventional chemical flooding methods and conventional chemicals combined with nanoparticles on a laboratory scale.The development of chemical EOR in the past few decades and the EOR policy given by the government of India has been mentioned in this review.The analysis provides an idea about enhanced recovery screening and implementation of chemical EOR methods in existing fields will significantly reduce the energy crisis in India.展开更多
Low permeability oil and gas resources are rich and have great potential all over the world, which has gradually become the main goal of oil and gas development. However, after traditional primary and secondary exploi...Low permeability oil and gas resources are rich and have great potential all over the world, which has gradually become the main goal of oil and gas development. However, after traditional primary and secondary exploitation, there is still a large amount of remaining oil that has not been recovered.Therefore, in recent years, enhanced oil recovery(EOR) technologies for low permeability reservoirs have been greatly developed to further improve crude oil production. This study presents a comprehensive review of EOR technologies in low permeability reservoirs with an emphasis on gas flooding, surfactant flooding, nanofluid flooding and imbibition EOR technologies. In addition, two kinds of gel systems are introduced for conformance control in low permeability reservoirs with channeling problems. Finally,the technical challenges, directions and outlooks of EOR in low permeability reservoirs are addressed.展开更多
基金the National Natural Science Foundation of China(U22B6005,52174043,52474035)the Beijing Natural Science Foundation(3242019)the China National Petroleum Corporation(CNPC)Innovation Foundation(2022DQ02-0208 and 2024DQ02-0114).
文摘High-water-cut mature reservoirs typically serve as the“ballast”for ensuring China’s annual crude oil production of 200 million tons.Despite the use of water flooding and chemical methods,over 40%of crude oil remains unexploited.It is critical to develop efficient revolutionary technologies to further enhance oil recovery(EOR)by a large percentage in high-water-cut mature reservoirs.To address this issue,the potential of vertical remaining oil in Daqing Oilfield is first analyzed from massive monitoring data.Using molecular dynamics simulation to design optimal synthetic routine,a copolymer without flu-orine or silicon is synthesized by modifying vinyl acetate(VAc)with maleic anhydride(MA)and styrene(St),and treated as a supercritical CO_(2)(scCO_(2))thickener.The underlying EOR mechanism of the scCO_(2) thickener is thereafter clarified by high-temperature,high-pressure oil displacement experiments.The EOR effect by thickened scCO_(2) flooding in a typical high-water-cut mature reservoir is predicted,and future technological advancements of the technique are ultimately discussed.Results show that the ver-tical remaining oil enriched in weakly swept zones is a primary target for further EOR in high-water-cut mature reservoirs.The copolymer typically exhibits good solubility,strong dispersion stability,and high thickening effect in scCO_(2).Under an ambient pressure of 10 MPa and a temperature of 50℃,the disso-lution of copolymer at a mass concentration of 0.2%can effectively increase the viscosity of scCO_(2) by 39.4 times.Due to the synergistic effect between expanding vertical swept volume and inhibiting gas channel-ing,crude oil recovery can be further enhanced by 23.1%for a typical high-water-cut mature reservoir when the scCO_(2) viscosity is increased by 50 times.Our understandings demonstrate that the thickened scCO_(2) flooding technology has significant technical advantages in high-water-cut mature reservoirs,with challenges and future development directions in field-scale applications also highlighted.
文摘This paper describes a simple, easy process for screening microorganisms, and introduces a laboratory simulation device and process of microbial enhanced oil recovery (MEOR) , which is a necessary research step for trial in oilfields. The MEOR mechanism and the influence of adsorption, diffusion, metabolism, nutrition, porosity, and permeability are analyzed. The research indicates that different microbes have different efficiencies in EOR and that different culture types play different roles in EOR. The effect of syrup is better than that of glucose, and larger porosity is favorable to the reproduction and growth of microbes, thereby improving the oil recovery. Using crude oil as a single carbon source is more appreciable because of the decrease in cost of oil recovery. At the end of this paper, the development of polymerase chain reaction (PCR) for the future is discussed.
文摘The compound system of polyacrylamide hydrogels and surfactant solutions are used for enhanced oil recovery(EOR).The polyacrylamide hydrogels are injected into block high-permeability zones firstly,followed by a low-cost sacrificial agent,then an oil-displacing surfactant,and finally an aqueous polymer solution containing diethanolamine,to enhance oil production.The hydrogels are selected through oscillatory rheometry,while the surfactant is optimized after optical imaging analysis.The EOR performance of the compound system is evaluated through core flooding experiments and reservoir numerical simulation.Specifically,the properly cross-linked polyacrylamide hydrogel can be selected using its elastic modulus as a quantitative parameter while accounting for pore structure.The sacrificial agent is used to block active adsorption sites in the rock matrix before mobilizing more crude oil with a nonionic-anionic surfactant system.The addition of the mild organic alkali(diethanolamine)into the polymer slug reduces surfactant adsorption and improves sweep efficiency,thereby enhancing the oil-washing effect.Flooding experimental results show that the sequential injection of hydrogel and surfactant compositions prolongs the period of increasing pressure gradient during subsequent waterflooding and significantly boosts oil production,achieving a 21-percentage-point increase in oil displacement efficiency.Numerical simulation for the target reservoir in the West Siberian oil province confirms the effectiveness,projecting a maximum cumulative oil increase of 6851 t over three years.
基金funded by the Partnership for Skill in Applied Science,Engineering,and Technology(PASET)under the Regional Scholarship Innovation Fund(RSIF).
文摘Nanoparticles are increasingly used in chemical enhanced oil recovery(CEOR)due to their ability to improve oil recovery by altering reservoir rock and fluid properties.These nanoparticles,which have unique physical and chemical traits,can be synthesized chemically or biologically.Biological synthesis,involving fungi,bacteria,algae,yeast,or plant materials are more stable,efficient,cost-effective,and environmentally friendly.With rising global energy demand and a shift towards greener solutions,the focus has moved from hazardous chemical synthesis to green synthesis for CEOR.Although some research exists on green nanoparticles for oil recovery,a comprehensive review of these studies and the mechanisms(such as wettability alteration,interfacial tension reduction,and stability enhancement)is needed.This paper reviews recent advances in the biosynthesis of nanoparticles and nanocomposites for oil recovery,highlighting successful examples like SiO_(2)/Montmorillonite/Xanthan and Fe3O4/SiO_(2)/Xanthan,which improved recovery by altering wettability,reducing interfacial tension,and enhancing dispersion and thermal stability.The study also notes the preference for plant-based green synthesis over microbial synthesis due to complexity and cost.The findings provide insights into the impact of novel greenly synthesized nanoparticles in CEOR.
基金the financial supports partially by the National Natural Science Foundation of China(22078296,21576240)the Zhejiang Provincial Natural Science Foundation of China (LD21B060001)。
文摘The displacement of residual crude oil and enhanced oil recovery from reservoirs of mature oil fields are challenging worldwide and have received intensive attentions in oil and gas industry.In this work,a novel method for enhanced oil recovery by displacement of oil with bionanofluids was proposed.Microdisplacement hydrodynamics of crude oil in microchannel sand-packed porous media by the bionanofluid were investigated by high-speed imaging.The machine learning models with the extreme gradient boosting(XGBoost) algorithm was developed for the prediction of residual oil saturation during the micro-displacement processes.The residual oil droplets within the porous media after the waterflooding were effectively removed through bionanofluid-flooding,resulting in additional enhanced oil recovery of 39.0%,which is double the recovery achieved by waterflooding at the same displacement velocity.By wavelet-transform image enhancement and the XGBoost algorithm in the machine learning,the residual oil saturations along the porous media were predicted accurately with the mean squared errors of 0.0045 and 0.0030 in the waterflooding and the bionanofluid-flooding,respectively.The results indicated that the machine learning is effective in characterizing the displacement behaviors and the bionanofluid-flooding could be an interesting approach,and thus has potential applications in enhanced oil recovery of waterflooding reservoirs.
基金express gratitude to Universiti Teknologi Malaysia Johor Bahru(Grant number:R.J130000.7651.4C318)the Malaysian Ministry of Higher Education(MOHE)for funding this study.
文摘The present study evaluated commercial starch behavior and tapioca starch nanoparticles(TSNP) with100 ppm ultralow salinity formation water as a potential alternative for enhanced oil recovery(EOR).Generally, starch exhibits excellent properties as a conventional viscosifier substitute in the petroleum industry. This study proposed a conventional polymer substitute, which is typically hydrolyzed polyacrylamide(HPAM) or oxide nanoparticles, for chemical flooding EOR employment. The TSNP was successfully synthesized via nanoprecipitation with ethanol as the precipitant medium. Two TSNP of different sizes, 1% and 3%, are successfully synthesized, which demonstrated chemical and physical attributes almost identical to raw tapioca starch(TS), corroborating their composition similarities. The 1%TSNP was significantly smaller compared to the 3% TSNP, but both samples possessed distinct angular,polygonal, and truncated shapes with sharp edges. Although the structure of the TSNP synthesized was a C-type crystal, their crystallinity was slightly lower. Fourier-transform infrared(FTIR) and energy dispersive X-ray(EDX) analyses confirmed similar chemical compositions of the raw TS and TSNP assessed. The EOR formulations employed in the study were prepared with various TS and TSNP concentrations, ranging from 0 ppm to 2000 ppm. The formulations were assessed at various temperatures between 25°C and 75°C. Rheological results indicated that TS and TSNP formulations coupled with low salinity formation water yielded non-Newtonian shear thickening behavior with respect to starch types,concentrations, temperatures, and shear rates. The 1% TSNP formulation exhibited favorable solution viscosifying criteria than the 3% TSNP sample within evaluated parameters. Surface tension, IFT, and wettability alteration measurements revealed indirect and inconclusive trend regarding TSNP concentrations and temperatures. Nonetheless, adding 1% and 3% TSNP considerably influenced IFT reduction and wettability alteration in several favorable combinations, indicating feasibility for EOR applications.
基金Supported by the National Key R&D Program of China(2019YFA0708700,2023YFF0614100)CNPC Major Science and Technology Project(2021ZZ01,2023ZZ04).
文摘Given that a large amount of crude oil remains on the surface of rocks and is difficult to produce after conventional waterflooding,a new superwetting oil displacement system incorporating the synergy between a hydroxyl anion compound(1OH-1C)and an extended surfactant(S-C_(13)PO_(13)S)was designed.The interfacial tension,contact angle and emulsification performance of the system were measured.The oil displacement effects and improved oil recovery(IOR)mechanisms of 1OH-1C,S-C_(13)PO_(13)S and their compound system were investigated by microscopic visualization oil displacement experiments and core displacement experiments.The results show that 1OH-1C creates a superwetting interface and electrostatic separation pressure on the solid surface,which destroys the strong interactions between crude oil and quartz to peel off the oil film.S-C_(13)PO_(13)S has low interfacial tension,which can promote the flow of remaining oil and emulsify it into oil-in-water emulsions.The compound system of 1OH-1C and S-C_(13)PO_(13)S has both superwettability and low IFT,which can effectively improve oil recovery through a synergistic effect.The oil displacement experiment of low-permeability natural core shows that the compound solution can increase the oil recovery by 16.4 percentage points after waterflooding.This new high-efficiency system is promising for greatly improving oil recovery in low-permeability reservoirs.
基金supported by Sultan Qaboos University,Oman,under the project"Formulation of a New Chemical of Polymeric Nanofluid Using MWCNT for EOR in South Oman Oil Fields."。
文摘Polymer-based enhanced oil recovery boosts production in depleted oil fields.However,harsh reservoir conditions,such as high salinity and temperature,often reduce its effectiveness.This study explores the use of a new aqueous polymeric nanofluid to overcome these challenges.The polymer we evaluated was partially hydrolyzed polyacrylamide(HPAM)with 40%hydrolysis and a molecular weight of 10 MD.The objective of this investigation was to enhance the efficacy of HPAM by incorporating multiwalled carbon nanotubes functionalized with COOH(MwCNT-COOH).Various tests were conducted to evaluatethe polymeric nanofluid,including Fourier transform infrared spectroscopy for bonding detection,viscoelastic behavior analysis under static and dynamic shear rates,interfacial tension measurements using the spinning drop technique,and wettability alteration studies through contact angle measurements.The efficiency of the new nanofluid in enabling oil recovery was compared to that of conventional polymers through core flooding experiments.The optimized polymeric nanoparticle injection resulted in a 10%increase in recuperation.This suggests that polymeric nanofluids may be a plausible solution for enhancing oil recovery-a solution that could boost oil production in reservoirs.
文摘Enhanced oil recovery(EOR)refers to themanymethodologies used to augment the volume of crude oil extracted froman oil reservoir.These approaches are used subsequent to the exhaustion of basic and secondary recovery methods.There are three primary categories of Enhanced Oil Recovery(EOR):thermal,gas injection,and chemical.Enhanced oil recovery methods may be costly and intricate;yet,they facilitate the extraction of supplementary oil that would otherwise remain in the reservoir.Enhanced Oil Recovery(EOR)may prolong the lifespan of an oil field and augment the total output from a specific field.The parameters influencing oil recovery are a significant problem in Enhanced Oil Recovery(EOR)systems,necessitating further examination of the components that impact them.This research examined the impact of permeability fluctuations on fluid dynamics inside a sandstone reservoir and presented a contemporary overview of the three phases of Enhanced Oil Recovery(EOR),including detailed explanations of the methodologies used and the processes facilitating oil recovery.The challenges faced with several common EOR mechanisms were identified,and solutions were suggested.Additionally,the modern trend of incorporating nanotechnology and its synergistic impacts on the stability and efficacy of conventional chemicals for enhanced oil recovery(EOR)was scrutinised and evaluated.Ultimately,laboratory results and field activities were examined.The study looked closely at hownanoparticlesmove through reservoirs and evaluated enhanced oil recovery(EOR),mobility ratio,and fluid displacement efficiency.This study offers comprehensive insights into the use of enhanced oil recovery techniques for sustainable energy generation.
基金supported by the General Program of the National Natural Science Foundation of China(52074335)the National Key Research and Development Program of China(2022YFE0129900 and 2019YFA0708700)+1 种基金the Fundamental Research Funds for the Central Universities(23CX07003A)the Special Funding Program for the Operational Expenses of National Research Institutions(SKLDOG2024-ZYRC-01).
文摘In deep oil reservoir development,enhanced oil recovery(EOR)techniques encounter significant challenges under high-temperature and high-salinity conditions.Traditional profile-control agents often fail to maintain stable blocking under extreme conditions and exhibit poor resistance to high temperature and high salinity.This study develops a functionalized nanographite system(the MEGO system)with superior high-temperature dispersibility and thermosalinity-responsive capability through polyether amine(PEA)grafting and noncovalent interactions with disodium naphthalene sulfonate(DNS)molecules.The grafted PEA and DNS provide steric hindrance and electrostatic repulsion,enhancing thermal and salinity resistance.After ten days of aggregation,the MEGO system forms stable particle aggregates(55.51-61.80 lm)that are suitable for deep reservoir migration and profile control.Both experiments and simulations reveal that particle size variations are synergistically controlled by temperature and salt ions(Na^(+),Ca^(2+),and Mg^(2+)).Compared with monovalent ions,divalent ions promote nanographite aggregation more strongly through double-layer compression and bridging effects.In core displacement experiments,the MEGO system demonstrated superior performance in reservoirs with permeabilities ranging from 21.6 to 103 mD.The aggregates formed within the pore throats significantly enhanced flow resistance,expanded the sweep volume,and increased the overall oil recovery to 56.01%.This research indicates that the MEGO system holds excellent potential for EOR in deep oil reservoirs.
基金supported by the Natural Science Foundation of Shandong Province(ZR2021ME007)the National Natural Science Foundation in China(51574267)the Key Projects of China National Key Research and Development Plan(2019YFA0708703)。
文摘During oil displacement,surfactants often encounter challenges such as emulsion instability and channeling,which can compromise their efficiency.To address these issues,polymer microspheres were synthesized via reverse microemulsion polymerization using acrylamide,2-methyl-2-acrylamidopropane sulfonic acid,and stearyl methacrylate as monomers,with N,N-methylenebisacrylamide as the crosslinker.The microspheres were then combined with sodium alkyl alcohol polyoxyethylene ether carboxylate to enhance emulsion stability and expand the swept volume of surfactant.A stable reverse microemulsion system was prepared using the maximum water solubilization rate as the indicator,and microspheres were synthesized based on this system.The ability of the microspheres to enhance emulsion stability was systematically evaluated.The plugging performance and enhanced oil recovery(EOR)efficiency of the microsphere/surfactant composite system were assessed through core seepage and oil displacement experiments.The experimental results demonstrated that microspheres were successfully prepared in a water-in-oil reverse microemulsion system with a solubilization rate of 42%.The emulsion stability was evaluated under an oil-to-water ratio of 7:3,a temperature of 80℃,and a salinity of 44,592 mg/L,by manually shaking the test tube five times.It was observed that the complete phase separation time of the emulsion increased from 10 to 120 min after the addition of microspheres.Under different permeability conditions(100×10^(-3),300×10^(-3),500×10^(-3)μm^(2)),the recovery efficiency of the composite system increased by 4.5%,8.3%,and 4.8%,respectively,compared to a single surfactant system.The microspheres developed in this study enhanced emulsion stability and increased the swept volume of surfactant within the formation,significantly boosting its oil recovery efficiency.
基金support and funding from the National Natural Science Foundation of China(No.52174047)。
文摘Hydrogels are widely used in reservoir flow control to enhanced oil recovery.However,challenges such as environmental contamination from conventional crosslinkers,poor solubility of crosslinking agents,and short gelation times under high-temperature conditions(e.g.,150℃)have hindered their practical application.Herein,we present the synthesis of amine-functionalized carbon quantum dots(NH_(2)-CQDs),which act as both a nano-crosslinker and a nano-reinforcing agent within hydrogel systems.The NH_(2)-CQDs-incorporated hydrogel can remain stability for 300 days under the conditions of a mineralization degree of 2.11×10^(4)mg/mL and 170℃,and has high tensile strength(371 kPa),good toughness(49.6 kJ/m^(3)),excellent viscoelasticity(G'=960 Pa,G"=460 Pa)and shear resistance.In addition,NH_(2)-CQDs adds many hydroxyl groups to the hydrogel,which can be attached to the surface of various substances.At the same time,micro-nano capsules containing NH_(2)-CQDs were formed by self-assembly of hydrophobic SiO_(2)on water droplets,the NH_(2)-CQDs solution is encapsulated in a capsule,and when stimulated by external conditions(temperature,pH,surfactant),the capsule releases the NH_(2)-CQDs solution,this method greatly delays the crosslinking time between polymer and crosslinker at high temperature.Under the condition of 170℃and pH=7,the gelation time of 10%hydrophobic SiO_(2)coated hydrogel is 44 times that of uncoated hydrogel,which can be effectively used for deep formation flow control,and CQD give hydrogels fluorescence properties that can be used for underground signal tracking.
基金the Young Scientists Fund of the National Natural Science Foundation of China(52204063)the Key Laboratory of Shale Gas Exploration,Ministry of Natural Resources(Chongqing Institute of Geology and Mineral Resources),Chongqing,China(KLSGE-202202).
文摘This paper introduces a novel approach combining radial borehole fracturing with Water-Alternating-Gas(WAG)injection,enabling simultaneous WAG injection and shale oil production in a single vertical well.A numerical reservoir model incorporating the modified exponential non-Darcy law,stress sensitivity,and diffusion is established.The spatial distribution of permeability reduction shows that stress sensitivity enhances the non-Darcy effect,with apparent permeability decreasing to 0-92.1%of the initial value,highlighting the importance of maintaining reservoir pressure.Continuous CO_(2) flooding leads to early gas breakthrough,while continuous water flooding has less displacement efficiency.A 30%water-to-gas injection time ratio improves oil production and delays gas breakthrough compared to continuous CO_(2) injection.Optimal conditions for effective recovery are identified as an initial production period of 100 d and a well vertical spacing of 30 m.This study compares the production capacity of WAG operations under radial borehole fracturing and horizontal well fracturing.When the number of wells is two for both cases,the production capacity of radial borehole fracturing is comparable to that of five-stage horizontal well fracturing,indicating that radial borehole fracturing can serve as an alternative or supplement to horizontal well fracturing when the reservoir volume is limited.This study offers a new method and theoretical basis for the efficient development of shale oil.
基金supported by the Key Joint Fund of National Natural Science Foundation of China(U23B2085)China National Petroleum Corporation Innovation Fund(2022DQ02-0205).
文摘High-molecular-weight partially hydrolyzed polyacrylamide(HPAM)has extensively used in enhanced oil recovery(EOR)process;however,it suffers from poor injectivity into low-permeability oil reservoirs and compromised long-term thermal stability under reservoir conditions.To address these challenges,a viscoelastic surfactant,3-(N-erucamidopropyl-N,N-dimethyl ammonium)betaine(EDAB),was developed and systematically compared with HPAM.Experimental results demonstrate that EDAB outperforms HPAM in thermal resilience,salt tolerance,and interfacial activity.Unlike HPAM's thermal thinning behavior,EDAB displays thermo-thickening properties,with viscosity rising from 225 to 366 mPa⋅s as temperature increases from 25 to 55℃.EDAB maintains 100% viscosity retention under 80 mg⋅L^(−1) Ca^(2+)or Mg^(2+),whereas HPAM experiences 46%viscosity loss under identical ionic conditions.Core-flooding tests conducted under simulated Daqing oil reservoir conditions indicate that EDAB achieves a 1.4%higher incremental oil recovery factor than HPAM with equal initial solution concentration.When HPAM was employed as a mobility control for pre-or post-flush,EDAB elevates the recovery factor by 13.9%over water flooding.These comparative analyses underscore the potential of EDAB as a thermally stable,salt-insensitive alternative to HPAM,offering an optimized chemical strategy for EOR in challenging reservoir environments.The findings provide empirical validation for surfactant-based solutions to address HPAM's operational constraints in low-permeability formations.
基金supported by the National Natural Science Foundation of China(Nos.52374064,52274056)China Scholarship Council(No.202406450086).
文摘Carbon dioxide Enhanced Oil Recovery(CO_(2)-EOR)technology guarantees substantial underground CO_(2) sequestration while simultaneously boosting the production capacity of subsurface hydrocarbons(oil and gas).However,unreasonable CO_(2)-EOR strategies,encompassing well placement and well control parameters,will lead to premature gas channeling in production wells,resulting in large amounts of CO_(2) escape without any beneficial effect.Due to the lack of prediction and optimization tools that integrate complex geological and engineering information for the widely used CO_(2)-EOR technology in promising industries,it is imperative to conduct thorough process simulations and optimization evaluations of CO_(2)-EOR technology.In this paper,a novel optimization workflow that couples the AST-GraphTrans-based proxy model(Attention-based Spatio-temporal Graph Transformer)and multi-objective optimization algorithm MOPSO(Multi-objective Particle Swarm Optimization)is established to optimize CO_(2)-EOR strategies.The workflow consists of two outstanding components.The AST-GraphTrans-based proxy model is utilized to forecast the dynamics of CO_(2) flooding and sequestration,which includes cumulative oil production,CO_(2) sequestration volume,and CO_(2) plume front.And the MOPSO algorithm is employed for achieving maximum oil production and maximum sequestration volume by coordinating well placement and well control parameters with the containment of gas channeling.By the collaborative coordination of the two aforementioned components,the AST-GraphTrans proxy-assisted optimization workflow overcomes the limitations of rapid optimization in CO_(2)-EOR technology,which cannot consider high-dimensional spatio-temporal information.The effectiveness of the proposed workflow is validated on a 2D synthetic model and a 3D field-scale reservoir model.The proposed workflow yields optimizations that lead to a significant increase in cumulative oil production by 87%and 49%,and CO_(2) sequestration volume enhancement by 78%and 50%across various reservoirs.These findings underscore the superior stability and generalization capabilities of the AST-GraphTrans proxy-assisted framework.The contribution of this study is to provide a more efficient prediction and optimization tool that maximizes CO_(2) sequestration and oil recovery while mitigating CO_(2) gas channeling,thereby ensuring cleaner oil production.
基金Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20231488National Natural Science Foundation of China,Grant/Award Numbers:52378083,52078481。
文摘CO_(2)-enhanced oil recovery(CO_(2)-EOR)is an economically viable carbon capture,utilization,and storage(CCUS)technique that is widely practiced and greatly contributes to the achievement of carbon-neutral cities.However,studies on CO_(2)-EOR source-sink matching involving different emission sources,different carbon capture rates,and stepwise CO_(2)pipeline construction are scarce.Considering four types of carbon sources,including coal-fired power,iron and steel,cement,and chemical plants,with different CO_(2)capture rates(85%,90%,95%,and 100%,respectively),and using a five-phased construction plan with a 25-year build-up period,we developed a method for quantifying carbon emissions from different sources,calculating the effective storage of carbon in CO_(2)-EOR and optimizing CO_(2)-EOR source-sink matching to reduce project costs.Using the Subei Basin in the Jiangsu Province,China,as a case study,we calculated the theoretical CO_(2)-EOR storage to be 1.7408×10^(8)t and the effective CO_(2)-EOR storage to be 0.435×10^(8)t.We analyzed the completion rate of transportation pipelines,the number of connected carbon sources,and the mass of CO_(2)stored,as well as the cost-effectiveness and sensitivity.Implementation of CO_(2)-EOR effectively reduced the total cost of source-sink matching in the five-stage 25-year construction approach.The reduction of CO_(2)capture rates had no effect on the value of oil repelling.The capture cost significantly affected the total cost of source-sink matching,and the impacts of the carbon sources on the total cost were in the order coal-fired power>iron and steel>cement>chemical plants.This study provides an innovative tool for evaluating the CO_(2)storage potential of CO_(2)-EOR and provides an important framework for implementing CO_(2)-EOR and planning CCUS projects in the Subei Basin and similar regions.
基金funded by the Natural Science Foundation of Beijing Municipality(3232028)the National Natural Science Foundation of China(52274053)the National Foreign Expert Individual Project(H20240045)。
文摘The tight-tuff heavy oil reservoir exhibits severe heterogeneity and is characterized by high density,high viscosity,and a high wax content,posing significant challenges for its development.While CO_(2)huffand-puff(H-n-P)enhances oil recovery,these reservoirs struggle with low displacement efficiency.This study proposes a method that combines CO_(2)with an oil-soluble viscosity reducer to improve displacement efficiency in the H-n-P process for tight-tuff heavy oil reservoirs.It also focuses on evaluating pore utilization limits and optimizing the injection strategy.Core samples and crude oil from the TH oilfield(a tight-tuff heavy oil reservoir)were used to conduct online NMR core flooding experiments,including depletion development,water,CO_(2),and HDC(CO_(2)combined with an oil-soluble viscosity reducer)H-n-P injection processes.A single-porosity model accurately reflecting its geological characteristics was developed using the GEM component simulator within the CMG numerical simulation software to investigate the optimized schemes and the enhanced oil recovery potential for a tight-tuff heavy oil reservoir in the TH oilfield.This model was utilized to evaluate the impact of various injection strategies on oilfield recovery efficiency.The study was designed and implemented with five distinct injection schemes.Results showed that oil was produced primarily from large and medium pores during the depletion stage,while water H-n-P,with CO_(2)H-n-P,first targeted macropores,then mesopores,and micropores.The lower pore utilization limit was 0.0267μm.In the HDC H-n-P process,most oil was recovered from water-flooded pores.Still,HDC's lower injection capacity increased the pore utilization limit to 0.03μm,making micropore recovery difficult.Experimental and modeling results suggest that the optimal develo p ment plan for the TH oilfield is one cycle of HDC H-n-P followed by two cycles of CO_(2)H-n-P.This strategy leverages HDC's ability to promote water and oil recovery in the early stage and mass transfer and extraction capacity of CO_(2)in later cycles.Additionally,the characteristics of CO_(2)and HDC H-n-P processes,pore utilization,and recoverable oil(at the pore scale)were evaluated.The results of this study are crucial for refining the reservoir development plan.
文摘This paper describes the experience of Jilin oilfield trials for Microbial Enhanced Oil Recovery (MEOR). A new technique to identify microbes with DNA for MEOR has been established, and useful microbes selected for use in field trials. Behaviors of bacteria activated in the reservoir, oil recovery and water cut, and the viscosity of crude oil produced through huff & puff testing and flooding with molasses-injection tests, have been investigated in situ. CJF-002, which produces biopolysaccharide, is the best among the microbes used for field trials, as it can use molasses as nutrient and produce a small quantity of CO2 and a mass of water-insoluble biopolymer. The metabolic behavior in the reservoir showed that CJF-002 had a good potentiality for MEOR.
文摘India is currently producing crude oil from matured fields because of insufficient discoveries of new fields.Therefore,in order to control the energy crisis in India,enhanced oil recovery(EOR)techniques are required to reduce the import of crude from the OPEC(Organization of the Petroleum Exporting Countries).This review mentions chemical EOR techniques(polymers,surfactants,alkali,nanoparticles,and combined alkali-surfactant-polymer flooding)and operations in India.Chemical EOR methods are one of the most efficient methods for oil displacement.The efficiency is enhanced by interfacial tension(IFT)reduction using surfactants and alkali,and mobility control of injected water is done by adding a polymer to increase the volumetric sweep efficiency.This paper also reviews the current trend of chemical EOR,prospects of chemical EOR in Indian oilfields,the development of chemical EOR in India with their challenges raising with economics,and screening criteria for chemical EOR implementation on the field scale.Furthermore,the review gives a brief idea about chemical EOR implementation in Indian oilfields in future prospects to increase the additional oil recovery from existing depleted fields to reduce the import of crude oil.The outcome of this review depicts all chemical EOR operations and recovery rates both at the laboratory scale and field scale around the country.The additional recovery rates are compared from various chemical EOR methods like conventional chemical flooding methods and conventional chemicals combined with nanoparticles on a laboratory scale.The development of chemical EOR in the past few decades and the EOR policy given by the government of India has been mentioned in this review.The analysis provides an idea about enhanced recovery screening and implementation of chemical EOR methods in existing fields will significantly reduce the energy crisis in India.
基金supported by Key Program of National Natural Science Foundation of China (No. 52130401)National Natural Science Foundation of China (No. 52104055)+1 种基金China National Postdoctoral Program for Innovative Talents (No. BX20200386)China Postdoctoral Science Foundation (No. 2021M703586)。
文摘Low permeability oil and gas resources are rich and have great potential all over the world, which has gradually become the main goal of oil and gas development. However, after traditional primary and secondary exploitation, there is still a large amount of remaining oil that has not been recovered.Therefore, in recent years, enhanced oil recovery(EOR) technologies for low permeability reservoirs have been greatly developed to further improve crude oil production. This study presents a comprehensive review of EOR technologies in low permeability reservoirs with an emphasis on gas flooding, surfactant flooding, nanofluid flooding and imbibition EOR technologies. In addition, two kinds of gel systems are introduced for conformance control in low permeability reservoirs with channeling problems. Finally,the technical challenges, directions and outlooks of EOR in low permeability reservoirs are addressed.
