Polymerflooding is an effective method widely applied for enhancing oil recovery(EOR)by reducing the mobility ratio between theinjected water and crude oil.However,traditional polymers encounter challenges in high sali...Polymerflooding is an effective method widely applied for enhancing oil recovery(EOR)by reducing the mobility ratio between theinjected water and crude oil.However,traditional polymers encounter challenges in high salinity reservoirs due to their salt sensitivity.Toovercome this challenge,we synthesized a zwitterion polymer(PAMNS)with salt-induced tackifying property through copolymerization ofacrylamide and a zwitterion monomer,methylacrylamide propyl-N,N-dimethylbutylsulfonate(NS).NS monomer is obtained from thereaction between 1,4-butanesultone and dimethylamino propyl methylacrylamide.In this study,the rheological properties,salt responsiveness,and EOR efficiency of PAMNS were evaluated.Results demonstrate that PAMNS exhibits desirable salt-induced tackifyingcharacteristics,with viscosity increasing up to 2.4 times as the NaCl concentration reaches a salinity of 30×10^(4)mg L^(-1).Furthermore,highvalence ions possess a much stronger effect on enhancing viscosity,manifested as Mg^(2+)>Ca^(2+)>Na^(+).Molecular dynamics simulations(MD)andfluid dynamics experiment results demonstrate that PAMNS molecules exhibit a more stretched state and enhanced intermolecularassociations in high-salinity environments.It is because of the salt-induced tackifying,PAMNS demonstrates superior performance inpolymerflooding experiments under salinity ranges from 5×10^(4)mg L^(-1)to 20×10^(4)mg L^(-1),leading to 10.38–19.83%higher EOR thantraditional polymers.展开更多
By reviewing the development history of stimulation techniques for deep/ultra-deep oil and gas reservoirs,the new progress in this field in China and abroad has been summed up,including deeper understanding on formati...By reviewing the development history of stimulation techniques for deep/ultra-deep oil and gas reservoirs,the new progress in this field in China and abroad has been summed up,including deeper understanding on formation mechanisms of fracture network in deep/ultra-deep oil and gas reservoir,performance improvement of fracturing fluid materials,fine stratification of ultra-deep vertical wells,and mature staged multi-cluster fracturing technique for ultra-deep and highly deviated wells/horizontal wells.In light of the exploration and development trend of ultra-deep oil and gas reservoirs in China,the requirements and technical difficulties in ultra-deep oil and gas reservoir stimulation are discussed:(1)The research and application of integrated geological engineering technology is difficult.(2)The requirements on fracturing materials for stimulation are high.(3)It is difficult to further improve the production in vertical profile of the ultra-deep and hugely thick reservoirs.(4)The requirements on tools and supporting high-pressure equipment on the ground for stimulation are high.(5)It is difficult to achieve efficient stimulation of ultra-deep,high-temperature and high-pressure wells.(6)It is difficult to monitor directly the reservoir stimulation and evaluate the stimulation effect accurately after stimulation.In line with the complex geological characteristics of ultra-deep oil and gas reservoirs in China,seven technical development directions are proposed:(1)To establish systematic new techniques for basic research and evaluation experiments;(2)to strengthen geological research and improve the operational mechanism of integrating geological research and engineering operation;(3)to develop high-efficiency fracturing materials for ultra-deep reservoirs;(4)to research separated layer fracturing technology for ultra-deep and hugely thick reservoirs;(5)to explore fracture-control stimulation technology for ultra-deep horizontal well;(6)to develop direct monitoring technology for hydraulic fractures in ultra-deep oil and gas reservoirs;(7)to develop downhole fracturing tools with high temperature and high pressure tolerance and supporting wellhead equipment able to withstand high pressure.展开更多
On the basis of the characterization of microscopic pore-throats in shale oil reservoirs by high-pressure mercury intrusion technique, a grading evaluation standard of shale oil reservoirs and a lower limit for reserv...On the basis of the characterization of microscopic pore-throats in shale oil reservoirs by high-pressure mercury intrusion technique, a grading evaluation standard of shale oil reservoirs and a lower limit for reservoir formation were established. Simultaneously, a new method for the classification of shale oil flow units based on logging data was established. A new classification scheme for shale oil reservoirs was proposed according to the inflection points and fractal features of mercury injection curves: microscopic pore-throats(less than 25 nm), small pore-throats(25-100 nm), medium pore-throats(100-1 000 nm) and big pore-throats(greater than 1 000 nm). Correspondingly, the shale reservoirs are divided into four classes, I, II, III and IV according to the number of microscopic pores they contain, and the average pore-throat radii corresponding to the dividing points are 150 nm, 70 nm and 10 nm respectively. By using the correlation between permeability and pore-throat radius, the permeability thresholds for the reservoir classification are determined at 1.00× 10^(-3) μm^2, 0.40×10^(-3) μm^2 and 0.05×10^(-3) μm^2 respectively. By using the exponential relationship between porosity and permeability of the same hydrodynamic flow unit, a new method was set up to evaluate the reservoir flow belt index and to identify shale oil flow units with logging data. The application in the Dongying sag shows that the standard proposed is suitable for grading evaluation of shale oil reservoirs.展开更多
In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in...In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in this way and the wavelets extracted with the seismic statistics techniques were used separately for inverting the seismic data of the southern part of Tahe oilfield, Tarim basin. The results showed that the resolution of the wavelet inversion with the higher-order statistics method was greatly improved, and the wavelet-inverted section could better distinguish the thin sandstone reservoirs of the upper and lower Carboniferous and their lateral distribution, providing a reliable basis of analysis for the study of thin sandstone reservoirs.展开更多
The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 hor...The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 horizontal wells.The synergy of three elements(storage,fracture and pressure)contributes to the enrichment and high production of shale oil in Jiyang Depression.The storage element controls the enrichment of shale oil;specifically,the presence of inorganic pores and fractures,as well as laminae of lime-mud rocks,in the saline lake basin,is conducive to the storage of shale oil,and the high hydrocarbon generating capacity and free hydrocarbon content are the material basis for high production.The fracture element controls the shale oil flow;specifically,natural fractures act as flow channels for shale oil to migrate and accumulate,and induced fractures communicate natural fractures to form complex fracture network,which is fundamental to high production.The pressure element controls the high and stable production of shale oil;specifically,the high formation pressure provides the drive force for the migration and accumulation of hydrocarbons,and fracturing stimulation significantly increases the elastic energy of rock and fluid,improves the imbibition replacement of oil in the pores/fractures,and reduces the stress sensitivity,guaranteeing the stable production of shale oil for a long time.Based on the ternary-element storage and flow concept,a 3D development technology was formed,with the core techniques of 3D well pattern optimization,3D balanced fracturing,and full-cycle optimization of adjustment and control.This technology effectively guides the production and provides a support to the large-scale beneficial development of shale oil in Jiyang Depression.展开更多
Experiments on surface-active polymer flooding for enhanced oil recovery were carried out by detection analysis and modern physical simulation technique based on reservoirs and fluids in Daqing placanticline oilfield....Experiments on surface-active polymer flooding for enhanced oil recovery were carried out by detection analysis and modern physical simulation technique based on reservoirs and fluids in Daqing placanticline oilfield.The experimental results show that the surface-active polymer is different from other common polymers and polymer-surfactant systems in molecular aggregation,viscosity and flow capacity,and it has larger molecular coil size,higher viscosity and viscosifying capacity,and poorer mobility.The surface-active polymer solution has good performance of viscosity-increasing and viscosity retention,and has good performance of viscoelasticity and deformability to exert positive effects of viscosifying and viscoelastic properties.Surface-active polymer can change the chemical property of interface and reduce interfacial tension,making the reservoir rock turn water-wet,also it can emulsify the oil into relatively stable oil-in-water emulsion,and emulsification capacity is an important property to enhance oil washing efficiency under non-ultralow interfacial tension.The surface-active polymer flooding enlarges swept volume in two ways:Microscopically,the surface-active polymer has mobility control effect and can enter oil-bearing pores not swept by water to drive residual oil,and its mobility control effect has more contribution than oil washing capacity in enhancing oil recovery.Macroscopically,it has plugging capacity,and can emulsify and plug the dominant channels in layers with high permeability,forcing the injected fluid to enter the layer with medium or low permeability and low flow resistance,and thus enlarging swept volume.展开更多
This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandston...This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandstone reservoir.For this,we selected anionic Alpha Olefin Sulfonate(AOS)surfactants and studied their synergistic effects in mixtures with zwitterionic betaines to enhance foam performance.The laboratory workflow used to define the best formulation followed a de-risking approach in three consecutive phases.First,(phase 1)the main surfactant(AOS)was selected among a series of commercial candidates in static conditions.Then,(phase 2)the betaine booster to be combined with the previously selected AOS was chosen and their ratio optimized in static conditions.Subsequently,(phase 3)the surfactant/booster ratio was optimized under dynamic conditions in a porous medium in the absence and the presence of oil.As a result of this study,a mixture of an AOS C14-C16 and cocamidopropyl hydroxysultaine(CAPHS)was selected as the one having the best performance.The designed formulation was proven to be robust in a wide range of conditions.It generated a strong and stable foam at reservoir conditions,overcoming variations in salinity and foam quality,and tolerated the presence of oil.展开更多
基金support of the National Natural Science Foundation of China(No.52120105007)the National Key Research and Development Program of China(2019Y FA0708700)are gratefully acknowledged.
文摘Polymerflooding is an effective method widely applied for enhancing oil recovery(EOR)by reducing the mobility ratio between theinjected water and crude oil.However,traditional polymers encounter challenges in high salinity reservoirs due to their salt sensitivity.Toovercome this challenge,we synthesized a zwitterion polymer(PAMNS)with salt-induced tackifying property through copolymerization ofacrylamide and a zwitterion monomer,methylacrylamide propyl-N,N-dimethylbutylsulfonate(NS).NS monomer is obtained from thereaction between 1,4-butanesultone and dimethylamino propyl methylacrylamide.In this study,the rheological properties,salt responsiveness,and EOR efficiency of PAMNS were evaluated.Results demonstrate that PAMNS exhibits desirable salt-induced tackifyingcharacteristics,with viscosity increasing up to 2.4 times as the NaCl concentration reaches a salinity of 30×10^(4)mg L^(-1).Furthermore,highvalence ions possess a much stronger effect on enhancing viscosity,manifested as Mg^(2+)>Ca^(2+)>Na^(+).Molecular dynamics simulations(MD)andfluid dynamics experiment results demonstrate that PAMNS molecules exhibit a more stretched state and enhanced intermolecularassociations in high-salinity environments.It is because of the salt-induced tackifying,PAMNS demonstrates superior performance inpolymerflooding experiments under salinity ranges from 5×10^(4)mg L^(-1)to 20×10^(4)mg L^(-1),leading to 10.38–19.83%higher EOR thantraditional polymers.
基金Supported by the China National Science and Technology Major Project(2016ZX05023)Petro China Science and Technology Major Project(2018E-1809)。
文摘By reviewing the development history of stimulation techniques for deep/ultra-deep oil and gas reservoirs,the new progress in this field in China and abroad has been summed up,including deeper understanding on formation mechanisms of fracture network in deep/ultra-deep oil and gas reservoir,performance improvement of fracturing fluid materials,fine stratification of ultra-deep vertical wells,and mature staged multi-cluster fracturing technique for ultra-deep and highly deviated wells/horizontal wells.In light of the exploration and development trend of ultra-deep oil and gas reservoirs in China,the requirements and technical difficulties in ultra-deep oil and gas reservoir stimulation are discussed:(1)The research and application of integrated geological engineering technology is difficult.(2)The requirements on fracturing materials for stimulation are high.(3)It is difficult to further improve the production in vertical profile of the ultra-deep and hugely thick reservoirs.(4)The requirements on tools and supporting high-pressure equipment on the ground for stimulation are high.(5)It is difficult to achieve efficient stimulation of ultra-deep,high-temperature and high-pressure wells.(6)It is difficult to monitor directly the reservoir stimulation and evaluate the stimulation effect accurately after stimulation.In line with the complex geological characteristics of ultra-deep oil and gas reservoirs in China,seven technical development directions are proposed:(1)To establish systematic new techniques for basic research and evaluation experiments;(2)to strengthen geological research and improve the operational mechanism of integrating geological research and engineering operation;(3)to develop high-efficiency fracturing materials for ultra-deep reservoirs;(4)to research separated layer fracturing technology for ultra-deep and hugely thick reservoirs;(5)to explore fracture-control stimulation technology for ultra-deep horizontal well;(6)to develop direct monitoring technology for hydraulic fractures in ultra-deep oil and gas reservoirs;(7)to develop downhole fracturing tools with high temperature and high pressure tolerance and supporting wellhead equipment able to withstand high pressure.
基金Supported by the National Natural Science Foundation of China(41330313,41402122)China National Science and Technology Major Project(2017ZX05049004-003)+1 种基金Research Project Funded by the SINOPEC Corp.(P15028)Fundamental Research Funds for the Central Universities(15CX05046A,15CX07004A,17CX02074)
文摘On the basis of the characterization of microscopic pore-throats in shale oil reservoirs by high-pressure mercury intrusion technique, a grading evaluation standard of shale oil reservoirs and a lower limit for reservoir formation were established. Simultaneously, a new method for the classification of shale oil flow units based on logging data was established. A new classification scheme for shale oil reservoirs was proposed according to the inflection points and fractal features of mercury injection curves: microscopic pore-throats(less than 25 nm), small pore-throats(25-100 nm), medium pore-throats(100-1 000 nm) and big pore-throats(greater than 1 000 nm). Correspondingly, the shale reservoirs are divided into four classes, I, II, III and IV according to the number of microscopic pores they contain, and the average pore-throat radii corresponding to the dividing points are 150 nm, 70 nm and 10 nm respectively. By using the correlation between permeability and pore-throat radius, the permeability thresholds for the reservoir classification are determined at 1.00× 10^(-3) μm^2, 0.40×10^(-3) μm^2 and 0.05×10^(-3) μm^2 respectively. By using the exponential relationship between porosity and permeability of the same hydrodynamic flow unit, a new method was set up to evaluate the reservoir flow belt index and to identify shale oil flow units with logging data. The application in the Dongying sag shows that the standard proposed is suitable for grading evaluation of shale oil reservoirs.
文摘In this paper seismic inversion was used as a key technique and the seismic wavelet most suitable to the actual underground situation was extracted with the higher-order statistics algorithm. The wavelets extracted in this way and the wavelets extracted with the seismic statistics techniques were used separately for inverting the seismic data of the southern part of Tahe oilfield, Tarim basin. The results showed that the resolution of the wavelet inversion with the higher-order statistics method was greatly improved, and the wavelet-inverted section could better distinguish the thin sandstone reservoirs of the upper and lower Carboniferous and their lateral distribution, providing a reliable basis of analysis for the study of thin sandstone reservoirs.
基金Supported by Sinopec Key Science and Technology Research Project(P21060)。
文摘The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 horizontal wells.The synergy of three elements(storage,fracture and pressure)contributes to the enrichment and high production of shale oil in Jiyang Depression.The storage element controls the enrichment of shale oil;specifically,the presence of inorganic pores and fractures,as well as laminae of lime-mud rocks,in the saline lake basin,is conducive to the storage of shale oil,and the high hydrocarbon generating capacity and free hydrocarbon content are the material basis for high production.The fracture element controls the shale oil flow;specifically,natural fractures act as flow channels for shale oil to migrate and accumulate,and induced fractures communicate natural fractures to form complex fracture network,which is fundamental to high production.The pressure element controls the high and stable production of shale oil;specifically,the high formation pressure provides the drive force for the migration and accumulation of hydrocarbons,and fracturing stimulation significantly increases the elastic energy of rock and fluid,improves the imbibition replacement of oil in the pores/fractures,and reduces the stress sensitivity,guaranteeing the stable production of shale oil for a long time.Based on the ternary-element storage and flow concept,a 3D development technology was formed,with the core techniques of 3D well pattern optimization,3D balanced fracturing,and full-cycle optimization of adjustment and control.This technology effectively guides the production and provides a support to the large-scale beneficial development of shale oil in Jiyang Depression.
基金Supported by China National Science and Technology Major Project(2016ZX05010002-004 and 2016ZX05023005-001-003)China Postdoctoral Science Foundation(2019M651255)National Natural Science Foundation of China(51804078).
文摘Experiments on surface-active polymer flooding for enhanced oil recovery were carried out by detection analysis and modern physical simulation technique based on reservoirs and fluids in Daqing placanticline oilfield.The experimental results show that the surface-active polymer is different from other common polymers and polymer-surfactant systems in molecular aggregation,viscosity and flow capacity,and it has larger molecular coil size,higher viscosity and viscosifying capacity,and poorer mobility.The surface-active polymer solution has good performance of viscosity-increasing and viscosity retention,and has good performance of viscoelasticity and deformability to exert positive effects of viscosifying and viscoelastic properties.Surface-active polymer can change the chemical property of interface and reduce interfacial tension,making the reservoir rock turn water-wet,also it can emulsify the oil into relatively stable oil-in-water emulsion,and emulsification capacity is an important property to enhance oil washing efficiency under non-ultralow interfacial tension.The surface-active polymer flooding enlarges swept volume in two ways:Microscopically,the surface-active polymer has mobility control effect and can enter oil-bearing pores not swept by water to drive residual oil,and its mobility control effect has more contribution than oil washing capacity in enhancing oil recovery.Macroscopically,it has plugging capacity,and can emulsify and plug the dominant channels in layers with high permeability,forcing the injected fluid to enter the layer with medium or low permeability and low flow resistance,and thus enlarging swept volume.
基金funded by the Centro para el Desarrollo Tecnologico Industrial(CDTI)of the Spanish Ministry of Science and Innovation(IDI-20170503)the Fundacion Cepsa with the Escuela Tecnica Superior de Ingenieros de Minas y Energia of the Universidad Politecnica de Madrid(UPM)。
文摘This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandstone reservoir.For this,we selected anionic Alpha Olefin Sulfonate(AOS)surfactants and studied their synergistic effects in mixtures with zwitterionic betaines to enhance foam performance.The laboratory workflow used to define the best formulation followed a de-risking approach in three consecutive phases.First,(phase 1)the main surfactant(AOS)was selected among a series of commercial candidates in static conditions.Then,(phase 2)the betaine booster to be combined with the previously selected AOS was chosen and their ratio optimized in static conditions.Subsequently,(phase 3)the surfactant/booster ratio was optimized under dynamic conditions in a porous medium in the absence and the presence of oil.As a result of this study,a mixture of an AOS C14-C16 and cocamidopropyl hydroxysultaine(CAPHS)was selected as the one having the best performance.The designed formulation was proven to be robust in a wide range of conditions.It generated a strong and stable foam at reservoir conditions,overcoming variations in salinity and foam quality,and tolerated the presence of oil.
