This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance senso...This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.展开更多
Through the analysis of the reservoir connection relationship and the water-cut rising rules after water breakthrough in the highly volatile oil AKPO oilfield, a new model of water-cut rising was established, and the ...Through the analysis of the reservoir connection relationship and the water-cut rising rules after water breakthrough in the highly volatile oil AKPO oilfield, a new model of water-cut rising was established, and the timing and strategy of water injection were put forward. The water-cut rising shapes of producers after water breakthrough can be divided into three types, and their water-cut rising mechanism is mainly controlled by reservoir connectivity. For the producers which directly connect with injectors in the single-phase sand body of the single-phase channel or lobe with good reservoir connectivity, the water-cut rising curve is "sub-convex". For the producers which connect with injectors through sand bodies developed in multi-phases with good inner sand connectivity but poorer physical property and connectivity at the overlapping parts of sands, the response to water injection is slow and the water-cut rising curve is "sub-concave". For the producers which connect with injectors through multi-phase sand bodies with reservoir physical properties, connectivity in between the former two and characteristics of both direct connection and overlapping connection, the response to water injection is slightly slower and the water-cut rising curve is "sub-S". Based on ratio relationship of oil and water relative permeability, a new model of water cut rising was established. Through the fitting analysis of actual production data, the optimal timing and corresponding technology for water injection after water breakthrough were put forward. Composite channel and lobe reservoirs can adopt water injection strategies concentrating on improving the vertical sweep efficiency and areal sweep efficiency respectively. This technology has worked well in the AKPO oilfield and can guide the development of similar oilfields.展开更多
Aiming at the complex flowing environment including the buried hill of Metamorphite, the active bottom water and the fracture at Budate Reservoir within Beir Depression of the Hailar Basin, combining the laboratory st...Aiming at the complex flowing environment including the buried hill of Metamorphite, the active bottom water and the fracture at Budate Reservoir within Beir Depression of the Hailar Basin, combining the laboratory studies and based on analysis of its drive mechanism, field wells’ parameters were used to analyze the effects of different conditions of the fractured metamorphic reservoir with bottom water on its law of wa-ter-cut variation and the waterflooding efficiency. The results show that for the Budate buried hill reservoir with bottom water, the gravity should be taken into consideration to determine reasonable perforation ratio and production pressure difference. And because of the acid sensitivity of the buried hill reservoir, application of proper clay stabilizer will enhance the field oil recovery to a satisfactory extent.展开更多
An accurate mapping and understanding of remaining oil distribution is very important for water control and stabilize oil production of mature oilfields in ultra-high water-cut stage.Currently,the Tuo-21 Fault Block o...An accurate mapping and understanding of remaining oil distribution is very important for water control and stabilize oil production of mature oilfields in ultra-high water-cut stage.Currently,the Tuo-21 Fault Block of the Shengtuo Oilfield has entered the stage of ultra-high water cut(97.2%).Poor adaptability of the well pattern,ineffective water injection cycle and low efficiency of engineering measures(such as workover,re-perforation and utilization of high-capacity pumps)are the significant problems in the ultra-high water-cut reservoir.In order to accurately describe the oil and water flow characteristics,relative permeability curves at high water injection multiple(injected pore volume)and a semiquantitative method is applied to perform fine reservoir simulation of the Sand group 3e7 in the Block.An accurate reservoir model is built and history matching is performed.The distribution characteristics of remaining oil in lateral and vertical directions are quantitatively simulated and analyzed.The results show that the numerical simulation considering relative permeability at high injection multiple can reflect truly the remaining oil distribution characteristics after water flooding in an ultrahigh water-cut stage.The distribution of remaining oil saturation can be mapped more accurately and quantitatively by using the‘four-points and five-types’classification method,providing a basis for potential tapping of various remaining oil types of oil reservoirs in late-stage of development with high water-cut.展开更多
Carbon dioxide(CO_(2))flooding is a widely applied recovery method during the tertiary recovery of oil and gas.A high water saturation condition in reservoirs could induce a‘water shielding’phenomenon after the inje...Carbon dioxide(CO_(2))flooding is a widely applied recovery method during the tertiary recovery of oil and gas.A high water saturation condition in reservoirs could induce a‘water shielding’phenomenon after the injection of CO_(2).This would prevent contact between the injected gas and the residual oil,restricting the development of the miscible zone.A micro-visual experiment of dead-end models,used to observe the effect of a film of water on the miscibility process,indicates that CO_(2)can penetrate the water film and come into contact with the residual oil,although the mixing is significantly delayed.However,the dissolution loss of CO_(2)at high water-cut conditions is not negligible.The oil-water partition coefficient,defined as the ratio of CO_(2)solubility in an oil-brine/two-phase system,keeps constant for specific reservoir conditions and changes little with an injection gas.The NMR device shows that when CO_(2)flooding follows water flooding,the residual oil decreasesdnot only in medium and large pores but also in small and micro pores.At levels of higher water saturation,CO_(2)displacement is characterized initially by a low oil production rate and high water-cut.After the CO_(2)breakthrough,the water-cut decreases sharply and the oil production rate increases gradually.The response time of CO_(2)flooding at high watercut reservoirs is typically delayed and prolonged.These results were confirmed in a pilot test for CO_(2)flooding at the P1-1 well group of the Pucheng Oilfield.Observations from this pilot study also suggest that a larger injection gas pore volume available for CO_(2)injection is required to offset the dissolution loss in high water saturation conditions.展开更多
Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to impro...Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to improve oil recovery for high water-cut multilayered reservoirs. Dif- ferent regroup scenarios may lead to different production performances. Based on unstable oil-water flow theory, a multilayer commingled reservoir simulator is established by modifying the production split method. Taking into account the differences of layer properties, including per- meability, oil viscosity, and remaining oil saturation, the pseudo flow resistance contrast is proposed to serve as a characteristic index of layer regrouping for high water-cut multilayered reservoirs. The production indices of multi- layered reservoirs with different pseudo flow resistances are predicted with the established model in which the data are taken from the Shengtuo Oilfield. Simulation results show that the pseudo flow resistance contrast should be less than 4 when the layer regrouping is implemented. The K-means clustering method, which is based on the objec- tive function, is used to automatically carry out the layer regrouping process according to pseudo flow resistances. The research result is applied to the IV-VI sand groups of the second member of the Shahejie Formation in the Shengtuo Oilfield, a favorable development performance is obtained, and the oil recovery is enhanced by 6.08 %.展开更多
To address the persistent challenge of dynamic mismatch between wellbore lifting capacity and reservoir fluid supply,and to establish a robust optimization framework for drainage operations in high-water-cut tight san...To address the persistent challenge of dynamic mismatch between wellbore lifting capacity and reservoir fluid supply,and to establish a robust optimization framework for drainage operations in high-water-cut tight sandstone gas reservoirs,this study systematically investigates the graded optimization and dynamic adaptation of drainage gas recovery technologies.Production data from a representative tight gas field were first employed to forecast reservoir performance.The predictive reliability was rigorously validated through high-precision history matching,thereby providing a quantitatively consistent foundation for subsequent wellbore optimization.Building on this characterization,a coupled simulation framework was developed that integrates wellbore multiphase flow modeling with nodal analysis based on the Inflow Performance Relationship,IPR,and the Vertical Lift Performance,VLP.This coordinated approach enables comprehensive evaluation of process adaptability and dynamic optimization of foam-assisted drainage,mechanical pumping,and jet pumping systems under evolving water-gas ratio,WGR conditions.The results reveal that a progressively increasing water-gas ratio is the dominant factor driving the transition from chemically assisted drainage methods to mechanically enhanced lifting technologies.A distinct quantitative threshold is identified at WGR≈0.002,beyond which mechanical intervention becomes more effective and economically justified.For mechanical pumping and jet pumping systems,a parameter inversion optimization strategy constrained by the target bottomhole flowing pressure,Pwf,is proposed to ensure stable production while maintaining reservoir drawdown control.In particular,the nozzle-to-throat area ratio of the jet pump is identified as the key governing parameter influencing entrainment capacity and lifting efficiency.Moreover,a configuration characterized by small pump diameter,long stroke length,and low operating speed is demonstrated to satisfy drainage requirements while mitigating torque fluctuations,enhancing volumetric efficiency,and improving pump fillage stability.展开更多
In deepwater clean energy development(hydrates and natural gas),as well as carbon capture,utilization and storage(CCUS)technologies,the formation and aggregation of hydrates in high water-cut systems can create flow b...In deepwater clean energy development(hydrates and natural gas),as well as carbon capture,utilization and storage(CCUS)technologies,the formation and aggregation of hydrates in high water-cut systems can create flow barriers and block pipelines or wellbores,causing economic losses even casualties.The anti-agglomerants(AAs)are known as both efficient and eco-friendly in preventing hydrate aggregation.However,due to the mass transfer promotion and low critical micelle concentration of AAs,they have not been widely used in industry.This study conducted a flowloop investigation on the evolution and prevention of hydrate flow barriers,and identified two primary hydrate blocking modes in high water-cut systems:rapid blocking(RB)by flocculated hydrates and gradual blocking by hydrate particle migration.Based on the cocamidopropyl dimethylamine's features,an improved high-efficiency anti-agglomerant,CDPKO,was developed.CDPKO prevented the emergence of RB,effectively reduced the hydrate aggregates of 150–500μm,and prolonged the sum of hydrate induction and blocking times by 53.5%–126%.The five micro mechanisms of CDPKO were elucidated:moderate foaming,promote adsorption,steric hindrance,break water cage,and mildly promote formation.When compounded with a thermodynamic inhibitor(ethylene glycol,5–15 wt%),CDPKO can reduce the usage of ethylene glycol by 64%–80%,while maintaining the original prevention effect.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51527805 and 11572220)
文摘This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.
基金Supported by the China National Science and Technology Major Project(2011ZX05030-005)
文摘Through the analysis of the reservoir connection relationship and the water-cut rising rules after water breakthrough in the highly volatile oil AKPO oilfield, a new model of water-cut rising was established, and the timing and strategy of water injection were put forward. The water-cut rising shapes of producers after water breakthrough can be divided into three types, and their water-cut rising mechanism is mainly controlled by reservoir connectivity. For the producers which directly connect with injectors in the single-phase sand body of the single-phase channel or lobe with good reservoir connectivity, the water-cut rising curve is "sub-convex". For the producers which connect with injectors through sand bodies developed in multi-phases with good inner sand connectivity but poorer physical property and connectivity at the overlapping parts of sands, the response to water injection is slow and the water-cut rising curve is "sub-concave". For the producers which connect with injectors through multi-phase sand bodies with reservoir physical properties, connectivity in between the former two and characteristics of both direct connection and overlapping connection, the response to water injection is slightly slower and the water-cut rising curve is "sub-S". Based on ratio relationship of oil and water relative permeability, a new model of water cut rising was established. Through the fitting analysis of actual production data, the optimal timing and corresponding technology for water injection after water breakthrough were put forward. Composite channel and lobe reservoirs can adopt water injection strategies concentrating on improving the vertical sweep efficiency and areal sweep efficiency respectively. This technology has worked well in the AKPO oilfield and can guide the development of similar oilfields.
文摘Aiming at the complex flowing environment including the buried hill of Metamorphite, the active bottom water and the fracture at Budate Reservoir within Beir Depression of the Hailar Basin, combining the laboratory studies and based on analysis of its drive mechanism, field wells’ parameters were used to analyze the effects of different conditions of the fractured metamorphic reservoir with bottom water on its law of wa-ter-cut variation and the waterflooding efficiency. The results show that for the Budate buried hill reservoir with bottom water, the gravity should be taken into consideration to determine reasonable perforation ratio and production pressure difference. And because of the acid sensitivity of the buried hill reservoir, application of proper clay stabilizer will enhance the field oil recovery to a satisfactory extent.
基金funded by SINOPEC Science and Technology Project P18080by National Energy Administration Research and Development Center Project.
文摘An accurate mapping and understanding of remaining oil distribution is very important for water control and stabilize oil production of mature oilfields in ultra-high water-cut stage.Currently,the Tuo-21 Fault Block of the Shengtuo Oilfield has entered the stage of ultra-high water cut(97.2%).Poor adaptability of the well pattern,ineffective water injection cycle and low efficiency of engineering measures(such as workover,re-perforation and utilization of high-capacity pumps)are the significant problems in the ultra-high water-cut reservoir.In order to accurately describe the oil and water flow characteristics,relative permeability curves at high water injection multiple(injected pore volume)and a semiquantitative method is applied to perform fine reservoir simulation of the Sand group 3e7 in the Block.An accurate reservoir model is built and history matching is performed.The distribution characteristics of remaining oil in lateral and vertical directions are quantitatively simulated and analyzed.The results show that the numerical simulation considering relative permeability at high injection multiple can reflect truly the remaining oil distribution characteristics after water flooding in an ultrahigh water-cut stage.The distribution of remaining oil saturation can be mapped more accurately and quantitatively by using the‘four-points and five-types’classification method,providing a basis for potential tapping of various remaining oil types of oil reservoirs in late-stage of development with high water-cut.
文摘Carbon dioxide(CO_(2))flooding is a widely applied recovery method during the tertiary recovery of oil and gas.A high water saturation condition in reservoirs could induce a‘water shielding’phenomenon after the injection of CO_(2).This would prevent contact between the injected gas and the residual oil,restricting the development of the miscible zone.A micro-visual experiment of dead-end models,used to observe the effect of a film of water on the miscibility process,indicates that CO_(2)can penetrate the water film and come into contact with the residual oil,although the mixing is significantly delayed.However,the dissolution loss of CO_(2)at high water-cut conditions is not negligible.The oil-water partition coefficient,defined as the ratio of CO_(2)solubility in an oil-brine/two-phase system,keeps constant for specific reservoir conditions and changes little with an injection gas.The NMR device shows that when CO_(2)flooding follows water flooding,the residual oil decreasesdnot only in medium and large pores but also in small and micro pores.At levels of higher water saturation,CO_(2)displacement is characterized initially by a low oil production rate and high water-cut.After the CO_(2)breakthrough,the water-cut decreases sharply and the oil production rate increases gradually.The response time of CO_(2)flooding at high watercut reservoirs is typically delayed and prolonged.These results were confirmed in a pilot test for CO_(2)flooding at the P1-1 well group of the Pucheng Oilfield.Observations from this pilot study also suggest that a larger injection gas pore volume available for CO_(2)injection is required to offset the dissolution loss in high water saturation conditions.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University(IRT1294)the China National Science and Technology Major Projects(Grant No:2016ZX05011)
文摘Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to improve oil recovery for high water-cut multilayered reservoirs. Dif- ferent regroup scenarios may lead to different production performances. Based on unstable oil-water flow theory, a multilayer commingled reservoir simulator is established by modifying the production split method. Taking into account the differences of layer properties, including per- meability, oil viscosity, and remaining oil saturation, the pseudo flow resistance contrast is proposed to serve as a characteristic index of layer regrouping for high water-cut multilayered reservoirs. The production indices of multi- layered reservoirs with different pseudo flow resistances are predicted with the established model in which the data are taken from the Shengtuo Oilfield. Simulation results show that the pseudo flow resistance contrast should be less than 4 when the layer regrouping is implemented. The K-means clustering method, which is based on the objec- tive function, is used to automatically carry out the layer regrouping process according to pseudo flow resistances. The research result is applied to the IV-VI sand groups of the second member of the Shahejie Formation in the Shengtuo Oilfield, a favorable development performance is obtained, and the oil recovery is enhanced by 6.08 %.
基金supported by the Major Science and Technology Project of PetroChina Company Limited“Research on Key Technologies for Enhancing Recovery in Tight Sandstone Gas Reservoirs”,specifically under its third sub-project:“Research on Integrated Fracturing,Drainage,and Production Technology to Enhance Single-Well Production in Water-Bearing Gas Reservoirs”(Grant number:2023ZZ25YJ03).
文摘To address the persistent challenge of dynamic mismatch between wellbore lifting capacity and reservoir fluid supply,and to establish a robust optimization framework for drainage operations in high-water-cut tight sandstone gas reservoirs,this study systematically investigates the graded optimization and dynamic adaptation of drainage gas recovery technologies.Production data from a representative tight gas field were first employed to forecast reservoir performance.The predictive reliability was rigorously validated through high-precision history matching,thereby providing a quantitatively consistent foundation for subsequent wellbore optimization.Building on this characterization,a coupled simulation framework was developed that integrates wellbore multiphase flow modeling with nodal analysis based on the Inflow Performance Relationship,IPR,and the Vertical Lift Performance,VLP.This coordinated approach enables comprehensive evaluation of process adaptability and dynamic optimization of foam-assisted drainage,mechanical pumping,and jet pumping systems under evolving water-gas ratio,WGR conditions.The results reveal that a progressively increasing water-gas ratio is the dominant factor driving the transition from chemically assisted drainage methods to mechanically enhanced lifting technologies.A distinct quantitative threshold is identified at WGR≈0.002,beyond which mechanical intervention becomes more effective and economically justified.For mechanical pumping and jet pumping systems,a parameter inversion optimization strategy constrained by the target bottomhole flowing pressure,Pwf,is proposed to ensure stable production while maintaining reservoir drawdown control.In particular,the nozzle-to-throat area ratio of the jet pump is identified as the key governing parameter influencing entrainment capacity and lifting efficiency.Moreover,a configuration characterized by small pump diameter,long stroke length,and low operating speed is demonstrated to satisfy drainage requirements while mitigating torque fluctuations,enhancing volumetric efficiency,and improving pump fillage stability.
基金supported by the National Natural Science Foundation of China(52434002,51991363,U21B2069)the Major Scientific and Technological Innovation Projects in Shandong Province(2022CXGC020407)+1 种基金the China Postdoctoral Science Foundation(2024M753808)the Fundamental Research Funds for the Central Universities(24CX10004A)。
文摘In deepwater clean energy development(hydrates and natural gas),as well as carbon capture,utilization and storage(CCUS)technologies,the formation and aggregation of hydrates in high water-cut systems can create flow barriers and block pipelines or wellbores,causing economic losses even casualties.The anti-agglomerants(AAs)are known as both efficient and eco-friendly in preventing hydrate aggregation.However,due to the mass transfer promotion and low critical micelle concentration of AAs,they have not been widely used in industry.This study conducted a flowloop investigation on the evolution and prevention of hydrate flow barriers,and identified two primary hydrate blocking modes in high water-cut systems:rapid blocking(RB)by flocculated hydrates and gradual blocking by hydrate particle migration.Based on the cocamidopropyl dimethylamine's features,an improved high-efficiency anti-agglomerant,CDPKO,was developed.CDPKO prevented the emergence of RB,effectively reduced the hydrate aggregates of 150–500μm,and prolonged the sum of hydrate induction and blocking times by 53.5%–126%.The five micro mechanisms of CDPKO were elucidated:moderate foaming,promote adsorption,steric hindrance,break water cage,and mildly promote formation.When compounded with a thermodynamic inhibitor(ethylene glycol,5–15 wt%),CDPKO can reduce the usage of ethylene glycol by 64%–80%,while maintaining the original prevention effect.
