This study aimed to evaluate the effects of chemical dissolution on the properties of reservoirs by matrix acidizing,using synthetic carbonate rocks with and without fractures,prepared with limestone powder,epoxy resi...This study aimed to evaluate the effects of chemical dissolution on the properties of reservoirs by matrix acidizing,using synthetic carbonate rocks with and without fractures,prepared with limestone powder,epoxy resin(chemically inert)and fractures represented by non-woven geotextile strips positioned perpendicular to the fluid flow direction,to check their influence on the dissolution process.A system was developed using an acid injection cell to carry out acidizing tests,applying a solution of acetic acid and distilled water at constant pressure,to observe the organic acid-rock interaction for contact times of 36,72 and 108 h.Chemical and petrophysical tests,as well as image analyses using X-ray micro-computed tomography were conducted to characterize the acidizing effects.Changes in rock properties were observed as the contact time increased,particularly the increase in porosity and permeability.Was observed the formation of CO_(2) and calcium acetate as reaction products between calcite and acid solution.Ramified wormhole and uniform dissolution patterns were noted;moreover,fractures influenced the dissolution in regions where they were inserted,increasing the branches present along their structure and deviating the fluid flow to a perpendicular direction to the injection direction,especially observed at 72 h,highlighting the use of geotextile as a material that reproduces the fractures'transmissivity in synthetic samples.The methodologies used contributed to presenting the effects of mineral dissolution on the properties of reservoir rocks post-stimulation,emphasizing the importance of chemical/petrophysical aspects and the contribution of fractures to better understand the matrix acidizing efficiency in field.展开更多
The Lower Cambrian Longwangmiao dolomite gas reservoirs in the Sichuan Basin are characterized by well-developed natural micro-fractures and dissolved pores and cavities.Due to the strong heterogeneity of reservoirs a...The Lower Cambrian Longwangmiao dolomite gas reservoirs in the Sichuan Basin are characterized by well-developed natural micro-fractures and dissolved pores and cavities.Due to the strong heterogeneity of reservoirs and the serious damage of drilling and completion fluids,acid placement is difficult,and especially the acidizing stimulation of long-interval highly deviated wells or horizontal wells is more difficult.In this paper,the diverting mechanism and rheological behavior of viscoelastic surfactant(VES)based diverting acid was firstly investigated,and the diverting acid with good diversion performance and low secondary damage was selected as the main acid.Then,based on the experimental results of its rheological behaviors,an empirical model of effective viscosity was fitted and a two-scale wormhole propagation model was coupled.And accordingly,a mathematical model for the acidizing of self-diverting acid was established to simulate the pH value,Ca^(2+)concentration,effective viscosity and wormhole shape under the effect of diverting acid in long-interval highly deviated wells that are non-uniformly damaged.Finally,gelled acid and 5%VES diverting acid were compared in terms of their etched wormhole shapes,flow rate dis-tribution and acid imbibition profiles.It is shown that the diverting acid can obviously improve the acid imbibition profile of strong-heterogeneity reservoirs to intensify low-permeability reservoir stimulation.In view of the strong heterogeneity of Longwangmiao dolomite reservoirs and the complexities of drilling and completion fluid damage in the Sichuan Basin,a placement technology was developed for variable VES concentration diverting acid in horizontal wells and long-interval highly deviated wells completed with slotted liners.This acid placement technology has been practically applied in 8 wells and their cumulative gas production rate tested at the wellhead is 1233.46×10^(4)m^(3)/d.The average production stimulation ratio per well is up to 1.95.It provides a support for the efficient development of the Longwangmiao giant gas reservoir.展开更多
Using a liquid-solid phase inversion method, a hybrid matrix poly（vinylidene fluoride）（PVDF） membrane was prepared with alumina（Al2O3） nanoparticle addition. Pd/Fe nanoparticles（NPs） were successfully immobili...Using a liquid-solid phase inversion method, a hybrid matrix poly（vinylidene fluoride）（PVDF） membrane was prepared with alumina（Al2O3） nanoparticle addition. Pd/Fe nanoparticles（NPs） were successfully immobilized on the Al2O3/PVDF membrane, which was characterized by Scanning Electron Microscopy（SEM） and Transmission Electron Microscopy（TEM）. The micrographs showed that the Pd/Fe NPs were dispersed homogeneously. Several important experimental parameters were optimized, including the mechanical properties, contact angle and surface area of Al2O3/PVDF composite membranes with different Al2O3 contents. At the same time, the ferrous ion concentration and the effect of hydrophilization were studied. The results showed that the modified Al2O3/PVDF membrane functioned well as a support. The Al2O3/PVDF membrane with immobilized Pd/Fe NPs exhibited high efficiency in terms of dichloroacetic acid（DCAA） dechlorination. Additionally, a reaction pathway for DCAA dechlorination by Pd/Fe NPs immobilized on the Al2O3/PVDF membrane system was proposed.展开更多
Lipids are the basic components of cells that are involved in physiological processes such as energy transfer,signal transduction,cell growth,and apoptosis,thus playing important biological functions in organisms[1].M...Lipids are the basic components of cells that are involved in physiological processes such as energy transfer,signal transduction,cell growth,and apoptosis,thus playing important biological functions in organisms[1].Moreover,lipids are biomarkers for many diseases,including coronary heart disease,hepatitis C,and diabetes.A substantial number of studies have shown that obtaining accurate and comprehensive data on the spatial distribution of lipids is essential for investigating pathogenesis and identifying diagnostic biomarkers[2].展开更多
The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transp...The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transportations and reactions.Alveolate dissolved pores,krast caves,and natural fissures are the major reservoir spaces for the Sinian dolomite formation in the Anyue gas field of the Sichuan Basin.There were four categories of formation,which are matrix dominated,inter-breccia dissolved pore dominated,dissolved pore and cave dominated,and fissure and cave dominated,based on the development intensity and connectedness of caves and fissures.The caves and fissures make the wormhole formation and propagation particularly complicated.Firstly,the 3-D topological structure of dissolved pores,vugs,fissures and throats inside cores is quantitatively scanned by CT imaging technology for its feature of vivid and damage-free.Secondly,3-D patterns of wormhole are obtained with CT scanning after core flooding by acid.Additionally,the porethroat network model is reconstructed with digital cores technology.Then,the size and ratio of pore and throat before and after core flooding by acid is analyzed and the absolute permeability of pore scale flow is numerically simulated to understand the fundamental influence of pores and vugs distribution and connectedness on wormhole propagation.Lastly,the wormhole pattern gained by CT scanning and simulating with two-scale model is compared.Meanwhile,the corrected two-scale model is utilized to simulate the wormhole propagation for matrix acidizing and acid fracturing of Sinian fractured-vuggy dolomite in Anyue gas field,Sichuan Basin.The optimized injection rate and volume were in agreement with the characteristic matrix acidizing operating curve,which indicates that the two-scale model was suitable for matrix acidizing optimization design of such formations.In addition,the simulated acid etched fracture length with considering the dynamic wormhole leakoff was consistent with the well testing interpreted result.展开更多
基金support from Petrobras(PETRO-LEO BRASILEIRO)Maccaferri Do Brasil and Federal University of Pernambuco.
文摘This study aimed to evaluate the effects of chemical dissolution on the properties of reservoirs by matrix acidizing,using synthetic carbonate rocks with and without fractures,prepared with limestone powder,epoxy resin(chemically inert)and fractures represented by non-woven geotextile strips positioned perpendicular to the fluid flow direction,to check their influence on the dissolution process.A system was developed using an acid injection cell to carry out acidizing tests,applying a solution of acetic acid and distilled water at constant pressure,to observe the organic acid-rock interaction for contact times of 36,72 and 108 h.Chemical and petrophysical tests,as well as image analyses using X-ray micro-computed tomography were conducted to characterize the acidizing effects.Changes in rock properties were observed as the contact time increased,particularly the increase in porosity and permeability.Was observed the formation of CO_(2) and calcium acetate as reaction products between calcite and acid solution.Ramified wormhole and uniform dissolution patterns were noted;moreover,fractures influenced the dissolution in regions where they were inserted,increasing the branches present along their structure and deviating the fluid flow to a perpendicular direction to the injection direction,especially observed at 72 h,highlighting the use of geotextile as a material that reproduces the fractures'transmissivity in synthetic samples.The methodologies used contributed to presenting the effects of mineral dissolution on the properties of reservoir rocks post-stimulation,emphasizing the importance of chemical/petrophysical aspects and the contribution of fractures to better understand the matrix acidizing efficiency in field.
基金Project supported by the National Science and Technology Major Project“Large-scale Oil and Gas Fields and CBM Development:Demonstration Project of Large-scale Carbonate Gas Fields in Sichuan Basin”(Code:2016ZX05052)CNPC Major Science and Technology Project“Research and Application of Deep-Temperature and High-Pressure Sulfur Gas Reservoir Reformation Technology in Sichuan Basin”(Code:2016E-0609).
文摘The Lower Cambrian Longwangmiao dolomite gas reservoirs in the Sichuan Basin are characterized by well-developed natural micro-fractures and dissolved pores and cavities.Due to the strong heterogeneity of reservoirs and the serious damage of drilling and completion fluids,acid placement is difficult,and especially the acidizing stimulation of long-interval highly deviated wells or horizontal wells is more difficult.In this paper,the diverting mechanism and rheological behavior of viscoelastic surfactant(VES)based diverting acid was firstly investigated,and the diverting acid with good diversion performance and low secondary damage was selected as the main acid.Then,based on the experimental results of its rheological behaviors,an empirical model of effective viscosity was fitted and a two-scale wormhole propagation model was coupled.And accordingly,a mathematical model for the acidizing of self-diverting acid was established to simulate the pH value,Ca^(2+)concentration,effective viscosity and wormhole shape under the effect of diverting acid in long-interval highly deviated wells that are non-uniformly damaged.Finally,gelled acid and 5%VES diverting acid were compared in terms of their etched wormhole shapes,flow rate dis-tribution and acid imbibition profiles.It is shown that the diverting acid can obviously improve the acid imbibition profile of strong-heterogeneity reservoirs to intensify low-permeability reservoir stimulation.In view of the strong heterogeneity of Longwangmiao dolomite reservoirs and the complexities of drilling and completion fluid damage in the Sichuan Basin,a placement technology was developed for variable VES concentration diverting acid in horizontal wells and long-interval highly deviated wells completed with slotted liners.This acid placement technology has been practically applied in 8 wells and their cumulative gas production rate tested at the wellhead is 1233.46×10^(4)m^(3)/d.The average production stimulation ratio per well is up to 1.95.It provides a support for the efficient development of the Longwangmiao giant gas reservoir.
基金supported by the Nature Science Foundation of Heilongjiang Province (No. B201410)the Postdoctoral Foundation Project of Heilongjiang Province (No. LBH-Z13128)+3 种基金the Science and Technology Research Program of Education Bureau of Heilongjiang Province (No. 12531206)the Special Scientific Research Projects of Harbin Normal University (12XQXG02)the National Nature Science Foundation of China (No. 41030743)the National Nature Science Foundation of China (No. 42171217)
文摘Using a liquid-solid phase inversion method, a hybrid matrix poly（vinylidene fluoride）（PVDF） membrane was prepared with alumina（Al2O3） nanoparticle addition. Pd/Fe nanoparticles（NPs） were successfully immobilized on the Al2O3/PVDF membrane, which was characterized by Scanning Electron Microscopy（SEM） and Transmission Electron Microscopy（TEM）. The micrographs showed that the Pd/Fe NPs were dispersed homogeneously. Several important experimental parameters were optimized, including the mechanical properties, contact angle and surface area of Al2O3/PVDF composite membranes with different Al2O3 contents. At the same time, the ferrous ion concentration and the effect of hydrophilization were studied. The results showed that the modified Al2O3/PVDF membrane functioned well as a support. The Al2O3/PVDF membrane with immobilized Pd/Fe NPs exhibited high efficiency in terms of dichloroacetic acid（DCAA） dechlorination. Additionally, a reaction pathway for DCAA dechlorination by Pd/Fe NPs immobilized on the Al2O3/PVDF membrane system was proposed.
基金supported by the Key Research and Development Program of Zhejiang Province(2025C01135)the National Natural Science Foundation of China(31770384,21605164)+2 种基金the Youth Academic Team Project of Minzu University of China(10301-02200301)the Huayi Technology Innovation Center for Research Resources(HTIC P01 RR2017001A)the Key Laboratory Construction Funds of State Ethnic Affairs Commission of China(10301-02200303)。
文摘Lipids are the basic components of cells that are involved in physiological processes such as energy transfer,signal transduction,cell growth,and apoptosis,thus playing important biological functions in organisms[1].Moreover,lipids are biomarkers for many diseases,including coronary heart disease,hepatitis C,and diabetes.A substantial number of studies have shown that obtaining accurate and comprehensive data on the spatial distribution of lipids is essential for investigating pathogenesis and identifying diagnostic biomarkers[2].
基金The authors are grateful for the research support of the Postdoctoral Program of Postdoctoral Work Centre,Southwest Oil&Gas Field Company(No.20150304-08).
文摘The propagation of wormhole is vital important for matrix acidizing and acid fracturing in carbonate reservoirs.While the formation of acid dissolved wormhole is derived from heterogeneous physical and chemical transportations and reactions.Alveolate dissolved pores,krast caves,and natural fissures are the major reservoir spaces for the Sinian dolomite formation in the Anyue gas field of the Sichuan Basin.There were four categories of formation,which are matrix dominated,inter-breccia dissolved pore dominated,dissolved pore and cave dominated,and fissure and cave dominated,based on the development intensity and connectedness of caves and fissures.The caves and fissures make the wormhole formation and propagation particularly complicated.Firstly,the 3-D topological structure of dissolved pores,vugs,fissures and throats inside cores is quantitatively scanned by CT imaging technology for its feature of vivid and damage-free.Secondly,3-D patterns of wormhole are obtained with CT scanning after core flooding by acid.Additionally,the porethroat network model is reconstructed with digital cores technology.Then,the size and ratio of pore and throat before and after core flooding by acid is analyzed and the absolute permeability of pore scale flow is numerically simulated to understand the fundamental influence of pores and vugs distribution and connectedness on wormhole propagation.Lastly,the wormhole pattern gained by CT scanning and simulating with two-scale model is compared.Meanwhile,the corrected two-scale model is utilized to simulate the wormhole propagation for matrix acidizing and acid fracturing of Sinian fractured-vuggy dolomite in Anyue gas field,Sichuan Basin.The optimized injection rate and volume were in agreement with the characteristic matrix acidizing operating curve,which indicates that the two-scale model was suitable for matrix acidizing optimization design of such formations.In addition,the simulated acid etched fracture length with considering the dynamic wormhole leakoff was consistent with the well testing interpreted result.
