The effects of CO2 pressure,temperature and concentration on asphaltene precipitation induced by CO2 were studied using a high-pressure vessel,interfacial tensiometer,Fourier transform infrared (FTIR) and drill core...The effects of CO2 pressure,temperature and concentration on asphaltene precipitation induced by CO2 were studied using a high-pressure vessel,interfacial tensiometer,Fourier transform infrared (FTIR) and drill core displacement experimental apparatus.The results indicated that the content of asphaltene in crude oil decreased,and the interfacial tension between a model oil and distilled water increased,with an increase of CO2 pressure,decrease of temperature and increase of molar ratio of CO2 to crude oil when CO2 contacted crude oil in the high pressure vessel.The content of asphaltene in sweepout oil and the permeability of test cores both also decreased with an increase of CO2 flooding pressure.The main reason for changes in content of asphaltene in crude oil,in interfacial tension between model oil and distilled water and in the permeability of the test core is the precipitation of asphaltene which is an interfacially active substance in crude oil.Precipitation of asphaltene also blocks pores in the drill core which decreases the permeability.展开更多
The numerical simulation of polymer flooding is a complex task as this process involves complex physical and chemical reactions,and multiple sets of characteristic parameters are required to properly set the simulatio...The numerical simulation of polymer flooding is a complex task as this process involves complex physical and chemical reactions,and multiple sets of characteristic parameters are required to properly set the simulation.At present,such characteristic parameters are mainly obtained by empirical methods,which typically result in relatively large errors.By analyzing experimentally polymer adsorption,permeability decline,inaccessible pore volume,viscosity-concentration relationship,and rheology,in this study,a conversion equation is provided to convert the experimental data into the parameters needed for the numerical simulation.Some examples are provided to demonstrate the reliability of the proposed approach.展开更多
In this paper, based on heavy rain numerical forecast model AREM(Advanced Regional Eta Model), two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and ARE...In this paper, based on heavy rain numerical forecast model AREM(Advanced Regional Eta Model), two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and AREM-3DVAR with the same data source(NCEP forecast field, surface data and radio-soundings) during the period from 21 May to 30 July 2008 to investigate the effect of the two initialization schemes on the rainfall simulation. The result suggests that:(1) the forecast TS score by the AREM-LAPS is higher than that by the AREM-3DVAR for rainfall in different areas, at different valid time and with different intensity, especially for the heavy rain, rainstorm and extremely heavy rain;(2) the AREM-3DVAR can generally simulate the average rainfall distribution, but the forecast area is smaller and rainfall intensity is weaker than the observation, while the AREM-LAPS significantly improves the forecast;(3) the AREM-LAPS gives a better forecast for the south-north shift of rainfall bands and the rainfall intensity variation than the AREM-3DVAR;(4) the AREM-LAPS can give a better reproduction for the daily change in the mean-rainfall-rate of the main rain band, and rainfall intensity changes in the eastern part of Southwest China, the coastal area in South China, the middle-lower valleys of Yangtze river, the Valleys of Huaihe river, and Shandong peninsula, with the rainfall intensity roughly close to the observation, while the rainfall intensity simulated by the AREM-3DVAR is clearly weaker than the observation, especially in the eastern part of Southwest China; and(5) the comparison verification between the AREM-LAPS and AREM-3DVAR for more than 10 typical rainfall processes in the summer of 2008 indicates that the AREM-LAPS gives a much better forecast than AREM-3DVAR in rain-band area, rainfall location and intensity, and in particular, the rainfall intensity forecast is improved obviously.展开更多
Based on the characteristics of hydrodynamics and sediment transport in the bar area in the Modaomen Estuary,a flume experiment was performed to study the evolution of the longitudinal profile of the mouth bar.The mou...Based on the characteristics of hydrodynamics and sediment transport in the bar area in the Modaomen Estuary,a flume experiment was performed to study the evolution of the longitudinal profile of the mouth bar.The mouth bar evolution was investigated under the impacts of floods with different return periods as well as flood-wave interaction.The results showed that floods with different return periods had significant influences on the evolution of the river mouth bar.Particularly on the inner slope of the mouth bar,the sediment was substantially active and moveable.The inner slope and the bar crest tended to be remarkably scoured.The erosion was intensified with the increase of the magnitude of floods.Moreover,the bar crest moved seawards,while the elevation of the bar crest barely changed.Under the flood-wave interaction,a remarkable amount of erosion on the inner and outer slopes of the mouth bar was also found.The seaward displacement of the bar crest under the interaction of floods and waves was less than it was under only the impact of floods,while more deposition was found on the crest of the mouth bar in this case.展开更多
In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process ...In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process of flash flood. However, little attention was paid on bearing body of hazard, the clusters of buildings. Thus the real disaster mechanism of flash flood remains unclear.Accordingly, based on the experiments of artificial flash floods in a conceptual solid model, this paper focuses on the flood-impacted inundation characteristics of the building clusters at different locations of the gully model, in order to obtain a better understanding of the disaster process and the interaction between the flash floods and building clusters. The results showed that, in a typical smallscale flash flood gully with hot and dry climate, 1)clusters of buildings on an alluvial fan could reduce about 35% of the flooding area by blocking the diffusion of the flood to the depression areas, and could also promote the deposition in lower reaches of the river channel by blocking the overbank flow from going back into the channel, making the width-depth ratio of the channel larger. 2) The flash flood rates of disaster and hazard on the alluvial fan are generally higher than that of the inner gully. For the inner gully,buildings located on the beaches along the lower river and the transitional areas of the straight channel and channel bends can easily be affected because of their lower elevations. For the alluvial fan, buildings nearby the meanders suffer the greatest impacts because of bank collapsing and flooding. 3) The safe vertical distance from a building to the river channel is 13 m for the buildings in the inner gully under extreme floods. Below this threshold, the smaller the vertical distance is, the greater the risk exposure is. For the buildings on the alluvial fan, especially for the buildings near the concave bank of the top rush point,the horizontal distance is more important, and the safe value is 80 m under extreme floods.展开更多
This paper introduces the results of selecting and breeding a micro-organism, Strain I, and its core model experiment investigation for microbial enhanced oil recovery (MEOR). Strain I was separated from the formation...This paper introduces the results of selecting and breeding a micro-organism, Strain I, and its core model experiment investigation for microbial enhanced oil recovery (MEOR). Strain I was separated from the formation water of the Dagang oil field, with analytical results showing that Strain I is a gram-positive bacillus. A further study revealed that this strain has an excellent tolerance of environmental stresses: It can survive in conditions of 70℃, 30 wt% salinity and pH3.5-9.4. Strain I can metabolize biosurfactants that could increase the oil recovery ratio, use crude oil as the single carbon source, and decompose long-chain paraffin with a large molecular weight into short-chain paraffin with a small molecular weight. The core model experiment shows that Strain I enhances oil recovery well. Using 2 vol% of the fermentation solution of Strain I to displace the crude oil in the synthetic plastic bonding core could increase the recovery ratio by 21.6%.展开更多
Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced.Dedicated experiments have been carried out by changing th...Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced.Dedicated experiments have been carried out by changing the phase’s density,viscosity,velocity and interfacial tension to systematically analyze the characteristics of the water ring.On the basis of such experimental data,a mathematical model for pressure drop prediction has been introduced.This research shows that as long as the density of oil and water remains the same,a concentric water ring can effectively be formed.In such conditions,the oil-water viscosity difference has little effect on the shape of water ring,and it only affects the pressure drop.The greater the viscosity of heavy oil,the smaller the pressure drop of the oil-water ring transportation system.The influence of phases’interfacial tension on the characteristics and pressure drop of the heavy oil-water ring can be considered negligible.The pressure drop prediction model introduced on the basis of the Buckingham’s principle provides values in good agreement(95%)with the experimental data.展开更多
Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs,nine groups of experiments were designed and performed to analyze the interference characteristics and their influenci...Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs,nine groups of experiments were designed and performed to analyze the interference characteristics and their influencing factors during water flooding.Based on percolation theory,an inversion model for simulating waterflooding interferences was proposed to study the influence laws of different factors on interference characteristics.The results show that well spacing,permeability ratio,cave size,and cave location all affect the interference characteristics of water flooding.When the cave is located in high permeability fractures,or in the small well spacing direction,or close to the producer in an injection-production unit,the effects of water flooding are much better.When the large cave is located in the high-permeability or small well spacing direction,the well in the direction with lower permeability or smaller well spacing will see water breakthrough earlier.When the cave is in the higher permeability direction and the reserves between the water injector and producer differ greatly,the conductivity differences in different injection-production directions are favorable for water flooding.When the injection-production well pattern is constructed or recombined,it’s better to make the reserves of caves in different injection-production directions proportional to permeability,and inversely proportional to the well spacing.The well close to the cave should be a producer,and the well far from the cave should be an injector.Different ratios of cave reserves to fracture reserves correspond to different optimal well spacings and optimal permeability ratios.Moreover,both optimal well spacing and optimal permeability ratio increase as the ratio of cave reserves to fracture reserves increases.展开更多
In order to clarify the major influence factors of resistance coefficient and residual resistance coefficient, so as to provide the basis for optimizing the polymer flooding schemes in oilfield Z of Bohai Sea, artific...In order to clarify the major influence factors of resistance coefficient and residual resistance coefficient, so as to provide the basis for optimizing the polymer flooding schemes in oilfield Z of Bohai Sea, artificial cores were made by simulated the characteristic parameters of real reservoir and the spacing of production-injection wells. The main parameters considered include reservoir permeability, polymer solution concentration and polymer injection rate. Core experiment of polymer flooding was taken by considering all the main parameters. The result showed that resistance coefficient and residual resistance coefficient decrease with the increase of core permeability. Resistance coefficient and residual resistance coefficient increase with the increase of concentration of polymer solution. The increment of displacement pressure in low permeability core is higher than in medium and high permeability core. The resistance coefficient increase with higher displacing velocity, and the increment in high permeability core is higher than in low permeability?core. The displacement velocity has little effect on the residual resistance coefficient. The experimental results can effectively guide the formulation of polymer flooding scheme in offshore oilfields, and optimize the appropriate injection rate and concentration of polymer solution for different properties of reservoirs, thus ensuring the effectiveness of polymer flooding in offshore oilfields.展开更多
To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foa...To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foam assisted steam flooding,and CO2 assisted steam flooding under different perforation conditions are conducted,and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding.The experimental results show that after adjusting the perforation in late steam flooding,the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well;high temperature water,oil,and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid;and CO2 acted as a thermal insulation in the steam chamber at the top,reduced the steam partial pressure inside the steam chamber,and effectively improved the heat efficiency of injected steam.Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield,the CO2 assisted steam flooding for the J6 block was designed.The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%,the oil recovery increase from 16.1%to 21.5%,and the final oil recovery goes up to 66.5%compared to steam flooding after perforation adjustment.展开更多
In order to enhance the effect of polymer flooding in offshore oilfields, so as to realize the longer stable production period and higher oil recovery, the reservoir perforation positions of production wells and injec...In order to enhance the effect of polymer flooding in offshore oilfields, so as to realize the longer stable production period and higher oil recovery, the reservoir perforation positions of production wells and injection wells are taken as research objects. By analyzing the distribution of remaining oil and production characteristics under different perforation positions, the optimum perforation positions of production wells and injection wells are selected. Bohai oilfield L was taken as target oilfield in this article, according to the actual reservoir characteristic parameters, three-dimensional laboratory physical simulation experiments of water flooding and polymer flooding were carried out, the experiments include different perforation positions of production wells and injection wells. The research result showed that the influence of perforation position on residual oil and development characteristics of the model is obvious. When takes the scheme of injection well upper part perforated and production well all part perforated, the least of the remaining oil distribution, the longest of the production period without water. Contrast with other perforation schemes, its stable production period increase about 1.2 times, the oil recovery of water flooding increase 3.7% - 6.0%, the oil recovery of polymer flooding increase 2.5% - 4.1%. So it is recommended as the best perforation scheme. Preferable effect had been achieved when translating research findings into practice. It can serve as a reference to the similar offshore oilfield.展开更多
Based on the systematic summary of current research on oil bank, the definition of oil bank in the process of fire flooding and its quantitative indices were proposed; and a new one-dimensional positive dry-fire flood...Based on the systematic summary of current research on oil bank, the definition of oil bank in the process of fire flooding and its quantitative indices were proposed; and a new one-dimensional positive dry-fire flooding model considering temperature gradient was established based on the steady flow theory of gas and liquid phases. Single factor analysis and orthogonal experiments were adopted to verify the reliability and reveal the formation mechanisms and the controlling factors of the oil bank. Then the optimal conditions for the oil bank to form were discussed. The study results show the formation of the oil bank is controlled by 3 factors:(1) Oil bank would come into being within a certain temperature interval and above a critical value of temperature gradient(absolute value), with temperature too high or too low and temperature gradient absolute value lower than the critical value, the oil bank couldn't form.(2) For fire flooding process in heavy oil reservoirs, the viscosity of oil influences the width of oil bank and the speed at which oil bank forms; the lower the oil viscosity is, the wider the oil bank is and the faster the oil bank forms.(3) Oil saturation could affect the developing temperature and speed of oil bank. The favorable temperature at which oil bank develops gets lower and the accumulating speed of oil gets faster when the oil saturation is higher. By orthogonal experiments with the model, the optimal combinations of reservoir conditions for forming oil bank during fire flooding in heavy oil reservoirs can be worked out.展开更多
To accurately measure and evaluate the oil-water production profile of horizontal wells, a dynamic measurement experiment of oil-water two-phase flow in horizontal wells and numerical simulation were combined to estab...To accurately measure and evaluate the oil-water production profile of horizontal wells, a dynamic measurement experiment of oil-water two-phase flow in horizontal wells and numerical simulation were combined to establish a method for measuring the partial phase flow rate of oil-water two-phase stratified flow in horizontal wells. An experimental work was performed in horizontal oil-water two-phase flow simulation well using combination production logging tool including mini-capacitance sensor and mini-spinner. The combination tool provides a recording of holdup and velocity profiles at five different heights of the borehole cross-section. The effect of total flow rate and water-cut on the response of spinner and capacitive sensor at five measured positions were investigated. The capacitance water holdup interpolation imaging algorithm was used to determine the local fluid property and oil-water interface height, and the measured local fluid speed was combined with the numerical simulation result to establish an optimal calculation model for obtaining the partial phase flow rate of the oil-water two-phase stratified flow in the horizontal well. The calculated flow rates of five measured points are basically consistent with the experimental data, the total flow rate and water holdup from calculation are in agreement with the set values in the experiment too, suggesting that the method has high accuracy.展开更多
In 1453,Xu Youzhen,a scholar-bureaucrat and hydrologist in Ming China,was dispatched to Shandong to find a way to harness the Yellow River.He proposed the opening up of multiple channels to diverge the flood waters.An...In 1453,Xu Youzhen,a scholar-bureaucrat and hydrologist in Ming China,was dispatched to Shandong to find a way to harness the Yellow River.He proposed the opening up of multiple channels to diverge the flood waters.An experiment was conducted to compare the efficiency of releasing water using one large opening with the use of a number of small openings.This experiment proved that opening up multiple channels outperformed the construction of only one,thereby convincing the emperor and officials of the efficacy of this method.Xu’s method for water control proved to be successful in averting a flood that occurred in 1456.展开更多
基金supported by the National Key Technologies R&D Program(2012BAC24B02)Basic Subject Fund of China University of Petroleum-Beijing(KYJJ2012-07-01)+1 种基金Basic Subject Fund of China University of Petroleum-Beijing(No.YJRC-2013-20)National Natural Science Foundation of China(51304222)
文摘The effects of CO2 pressure,temperature and concentration on asphaltene precipitation induced by CO2 were studied using a high-pressure vessel,interfacial tensiometer,Fourier transform infrared (FTIR) and drill core displacement experimental apparatus.The results indicated that the content of asphaltene in crude oil decreased,and the interfacial tension between a model oil and distilled water increased,with an increase of CO2 pressure,decrease of temperature and increase of molar ratio of CO2 to crude oil when CO2 contacted crude oil in the high pressure vessel.The content of asphaltene in sweepout oil and the permeability of test cores both also decreased with an increase of CO2 flooding pressure.The main reason for changes in content of asphaltene in crude oil,in interfacial tension between model oil and distilled water and in the permeability of the test core is the precipitation of asphaltene which is an interfacially active substance in crude oil.Precipitation of asphaltene also blocks pores in the drill core which decreases the permeability.
基金supported by Hubei Provincial Natural Science Foundation of China(Grant No.2020CFB377)the National Natural Science Foundation of China(Grant No.52104020).
文摘The numerical simulation of polymer flooding is a complex task as this process involves complex physical and chemical reactions,and multiple sets of characteristic parameters are required to properly set the simulation.At present,such characteristic parameters are mainly obtained by empirical methods,which typically result in relatively large errors.By analyzing experimentally polymer adsorption,permeability decline,inaccessible pore volume,viscosity-concentration relationship,and rheology,in this study,a conversion equation is provided to convert the experimental data into the parameters needed for the numerical simulation.Some examples are provided to demonstrate the reliability of the proposed approach.
基金Scientific Research Projects Specially for Public Welfare Industries(GYHY200906010)National Natural Science Foundation of China(41075034)Project 1009 for Wuhan Heavy Rain Institute
文摘In this paper, based on heavy rain numerical forecast model AREM(Advanced Regional Eta Model), two different initialization schemes, LAPS and GRAPES-3DVAR, are used to run assimilation experiments of AREM-LAPS and AREM-3DVAR with the same data source(NCEP forecast field, surface data and radio-soundings) during the period from 21 May to 30 July 2008 to investigate the effect of the two initialization schemes on the rainfall simulation. The result suggests that:(1) the forecast TS score by the AREM-LAPS is higher than that by the AREM-3DVAR for rainfall in different areas, at different valid time and with different intensity, especially for the heavy rain, rainstorm and extremely heavy rain;(2) the AREM-3DVAR can generally simulate the average rainfall distribution, but the forecast area is smaller and rainfall intensity is weaker than the observation, while the AREM-LAPS significantly improves the forecast;(3) the AREM-LAPS gives a better forecast for the south-north shift of rainfall bands and the rainfall intensity variation than the AREM-3DVAR;(4) the AREM-LAPS can give a better reproduction for the daily change in the mean-rainfall-rate of the main rain band, and rainfall intensity changes in the eastern part of Southwest China, the coastal area in South China, the middle-lower valleys of Yangtze river, the Valleys of Huaihe river, and Shandong peninsula, with the rainfall intensity roughly close to the observation, while the rainfall intensity simulated by the AREM-3DVAR is clearly weaker than the observation, especially in the eastern part of Southwest China; and(5) the comparison verification between the AREM-LAPS and AREM-3DVAR for more than 10 typical rainfall processes in the summer of 2008 indicates that the AREM-LAPS gives a much better forecast than AREM-3DVAR in rain-band area, rainfall location and intensity, and in particular, the rainfall intensity forecast is improved obviously.
基金supported by the Changjiang River Scientific Research Institute(CRSRI)Open Research Program(Grant No.CKWV2017499/KY)the National Natural Science Foundation of China(Grant No.51779280)
文摘Based on the characteristics of hydrodynamics and sediment transport in the bar area in the Modaomen Estuary,a flume experiment was performed to study the evolution of the longitudinal profile of the mouth bar.The mouth bar evolution was investigated under the impacts of floods with different return periods as well as flood-wave interaction.The results showed that floods with different return periods had significant influences on the evolution of the river mouth bar.Particularly on the inner slope of the mouth bar,the sediment was substantially active and moveable.The inner slope and the bar crest tended to be remarkably scoured.The erosion was intensified with the increase of the magnitude of floods.Moreover,the bar crest moved seawards,while the elevation of the bar crest barely changed.Under the flood-wave interaction,a remarkable amount of erosion on the inner and outer slopes of the mouth bar was also found.The seaward displacement of the bar crest under the interaction of floods and waves was less than it was under only the impact of floods,while more deposition was found on the crest of the mouth bar in this case.
基金supported by the Specific Research of China Institute of Water Resources and Hydropower Research (Grant Nos. Fangji 1240)Chinese Ministry of Water Resources (Grant Nos. 201301058 and 20131059)the Basic Research Fund for Central Public Research Institutes (Grant No. CKSF2015010/TB)
文摘In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process of flash flood. However, little attention was paid on bearing body of hazard, the clusters of buildings. Thus the real disaster mechanism of flash flood remains unclear.Accordingly, based on the experiments of artificial flash floods in a conceptual solid model, this paper focuses on the flood-impacted inundation characteristics of the building clusters at different locations of the gully model, in order to obtain a better understanding of the disaster process and the interaction between the flash floods and building clusters. The results showed that, in a typical smallscale flash flood gully with hot and dry climate, 1)clusters of buildings on an alluvial fan could reduce about 35% of the flooding area by blocking the diffusion of the flood to the depression areas, and could also promote the deposition in lower reaches of the river channel by blocking the overbank flow from going back into the channel, making the width-depth ratio of the channel larger. 2) The flash flood rates of disaster and hazard on the alluvial fan are generally higher than that of the inner gully. For the inner gully,buildings located on the beaches along the lower river and the transitional areas of the straight channel and channel bends can easily be affected because of their lower elevations. For the alluvial fan, buildings nearby the meanders suffer the greatest impacts because of bank collapsing and flooding. 3) The safe vertical distance from a building to the river channel is 13 m for the buildings in the inner gully under extreme floods. Below this threshold, the smaller the vertical distance is, the greater the risk exposure is. For the buildings on the alluvial fan, especially for the buildings near the concave bank of the top rush point,the horizontal distance is more important, and the safe value is 80 m under extreme floods.
文摘This paper introduces the results of selecting and breeding a micro-organism, Strain I, and its core model experiment investigation for microbial enhanced oil recovery (MEOR). Strain I was separated from the formation water of the Dagang oil field, with analytical results showing that Strain I is a gram-positive bacillus. A further study revealed that this strain has an excellent tolerance of environmental stresses: It can survive in conditions of 70℃, 30 wt% salinity and pH3.5-9.4. Strain I can metabolize biosurfactants that could increase the oil recovery ratio, use crude oil as the single carbon source, and decompose long-chain paraffin with a large molecular weight into short-chain paraffin with a small molecular weight. The core model experiment shows that Strain I enhances oil recovery well. Using 2 vol% of the fermentation solution of Strain I to displace the crude oil in the synthetic plastic bonding core could increase the recovery ratio by 21.6%.
基金Foundation Projects:Major National R&D Project(2016ZX05025-004-005).
文摘Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced.Dedicated experiments have been carried out by changing the phase’s density,viscosity,velocity and interfacial tension to systematically analyze the characteristics of the water ring.On the basis of such experimental data,a mathematical model for pressure drop prediction has been introduced.This research shows that as long as the density of oil and water remains the same,a concentric water ring can effectively be formed.In such conditions,the oil-water viscosity difference has little effect on the shape of water ring,and it only affects the pressure drop.The greater the viscosity of heavy oil,the smaller the pressure drop of the oil-water ring transportation system.The influence of phases’interfacial tension on the characteristics and pressure drop of the heavy oil-water ring can be considered negligible.The pressure drop prediction model introduced on the basis of the Buckingham’s principle provides values in good agreement(95%)with the experimental data.
基金Supported by the China National Science and Technology Major Project(2016ZX05014-003-004)
文摘Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs,nine groups of experiments were designed and performed to analyze the interference characteristics and their influencing factors during water flooding.Based on percolation theory,an inversion model for simulating waterflooding interferences was proposed to study the influence laws of different factors on interference characteristics.The results show that well spacing,permeability ratio,cave size,and cave location all affect the interference characteristics of water flooding.When the cave is located in high permeability fractures,or in the small well spacing direction,or close to the producer in an injection-production unit,the effects of water flooding are much better.When the large cave is located in the high-permeability or small well spacing direction,the well in the direction with lower permeability or smaller well spacing will see water breakthrough earlier.When the cave is in the higher permeability direction and the reserves between the water injector and producer differ greatly,the conductivity differences in different injection-production directions are favorable for water flooding.When the injection-production well pattern is constructed or recombined,it’s better to make the reserves of caves in different injection-production directions proportional to permeability,and inversely proportional to the well spacing.The well close to the cave should be a producer,and the well far from the cave should be an injector.Different ratios of cave reserves to fracture reserves correspond to different optimal well spacings and optimal permeability ratios.Moreover,both optimal well spacing and optimal permeability ratio increase as the ratio of cave reserves to fracture reserves increases.
文摘In order to clarify the major influence factors of resistance coefficient and residual resistance coefficient, so as to provide the basis for optimizing the polymer flooding schemes in oilfield Z of Bohai Sea, artificial cores were made by simulated the characteristic parameters of real reservoir and the spacing of production-injection wells. The main parameters considered include reservoir permeability, polymer solution concentration and polymer injection rate. Core experiment of polymer flooding was taken by considering all the main parameters. The result showed that resistance coefficient and residual resistance coefficient decrease with the increase of core permeability. Resistance coefficient and residual resistance coefficient increase with the increase of concentration of polymer solution. The increment of displacement pressure in low permeability core is higher than in medium and high permeability core. The resistance coefficient increase with higher displacing velocity, and the increment in high permeability core is higher than in low permeability?core. The displacement velocity has little effect on the residual resistance coefficient. The experimental results can effectively guide the formulation of polymer flooding scheme in offshore oilfields, and optimize the appropriate injection rate and concentration of polymer solution for different properties of reservoirs, thus ensuring the effectiveness of polymer flooding in offshore oilfields.
基金Supported by the China National Science and Technology Major Project(2016ZX05012-002).
文摘To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foam assisted steam flooding,and CO2 assisted steam flooding under different perforation conditions are conducted,and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding.The experimental results show that after adjusting the perforation in late steam flooding,the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well;high temperature water,oil,and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid;and CO2 acted as a thermal insulation in the steam chamber at the top,reduced the steam partial pressure inside the steam chamber,and effectively improved the heat efficiency of injected steam.Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield,the CO2 assisted steam flooding for the J6 block was designed.The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%,the oil recovery increase from 16.1%to 21.5%,and the final oil recovery goes up to 66.5%compared to steam flooding after perforation adjustment.
文摘In order to enhance the effect of polymer flooding in offshore oilfields, so as to realize the longer stable production period and higher oil recovery, the reservoir perforation positions of production wells and injection wells are taken as research objects. By analyzing the distribution of remaining oil and production characteristics under different perforation positions, the optimum perforation positions of production wells and injection wells are selected. Bohai oilfield L was taken as target oilfield in this article, according to the actual reservoir characteristic parameters, three-dimensional laboratory physical simulation experiments of water flooding and polymer flooding were carried out, the experiments include different perforation positions of production wells and injection wells. The research result showed that the influence of perforation position on residual oil and development characteristics of the model is obvious. When takes the scheme of injection well upper part perforated and production well all part perforated, the least of the remaining oil distribution, the longest of the production period without water. Contrast with other perforation schemes, its stable production period increase about 1.2 times, the oil recovery of water flooding increase 3.7% - 6.0%, the oil recovery of polymer flooding increase 2.5% - 4.1%. So it is recommended as the best perforation scheme. Preferable effect had been achieved when translating research findings into practice. It can serve as a reference to the similar offshore oilfield.
基金Supported by the China National Science and Technology Major Project(2016ZX05012-004)the PetroChina Science and Technology Project(2016B-1402)
文摘Based on the systematic summary of current research on oil bank, the definition of oil bank in the process of fire flooding and its quantitative indices were proposed; and a new one-dimensional positive dry-fire flooding model considering temperature gradient was established based on the steady flow theory of gas and liquid phases. Single factor analysis and orthogonal experiments were adopted to verify the reliability and reveal the formation mechanisms and the controlling factors of the oil bank. Then the optimal conditions for the oil bank to form were discussed. The study results show the formation of the oil bank is controlled by 3 factors:(1) Oil bank would come into being within a certain temperature interval and above a critical value of temperature gradient(absolute value), with temperature too high or too low and temperature gradient absolute value lower than the critical value, the oil bank couldn't form.(2) For fire flooding process in heavy oil reservoirs, the viscosity of oil influences the width of oil bank and the speed at which oil bank forms; the lower the oil viscosity is, the wider the oil bank is and the faster the oil bank forms.(3) Oil saturation could affect the developing temperature and speed of oil bank. The favorable temperature at which oil bank develops gets lower and the accumulating speed of oil gets faster when the oil saturation is higher. By orthogonal experiments with the model, the optimal combinations of reservoir conditions for forming oil bank during fire flooding in heavy oil reservoirs can be worked out.
基金Supported by National Natural Science Foundation of China(41474115)Open Fund of Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University)Ministry of Education of China(No K2018-02)Educational Commission of Hubei Province of China(D20141302)
文摘To accurately measure and evaluate the oil-water production profile of horizontal wells, a dynamic measurement experiment of oil-water two-phase flow in horizontal wells and numerical simulation were combined to establish a method for measuring the partial phase flow rate of oil-water two-phase stratified flow in horizontal wells. An experimental work was performed in horizontal oil-water two-phase flow simulation well using combination production logging tool including mini-capacitance sensor and mini-spinner. The combination tool provides a recording of holdup and velocity profiles at five different heights of the borehole cross-section. The effect of total flow rate and water-cut on the response of spinner and capacitive sensor at five measured positions were investigated. The capacitance water holdup interpolation imaging algorithm was used to determine the local fluid property and oil-water interface height, and the measured local fluid speed was combined with the numerical simulation result to establish an optimal calculation model for obtaining the partial phase flow rate of the oil-water two-phase stratified flow in the horizontal well. The calculated flow rates of five measured points are basically consistent with the experimental data, the total flow rate and water holdup from calculation are in agreement with the set values in the experiment too, suggesting that the method has high accuracy.
文摘In 1453,Xu Youzhen,a scholar-bureaucrat and hydrologist in Ming China,was dispatched to Shandong to find a way to harness the Yellow River.He proposed the opening up of multiple channels to diverge the flood waters.An experiment was conducted to compare the efficiency of releasing water using one large opening with the use of a number of small openings.This experiment proved that opening up multiple channels outperformed the construction of only one,thereby convincing the emperor and officials of the efficacy of this method.Xu’s method for water control proved to be successful in averting a flood that occurred in 1456.