As oil and gas development increasingly targets unconventional reservoirs,the limitations of conventional hydraulic fracturing,namely high water consumption and significant reservoir damage,have become more pronounced...As oil and gas development increasingly targets unconventional reservoirs,the limitations of conventional hydraulic fracturing,namely high water consumption and significant reservoir damage,have become more pronounced.This has driven growing interest in the development of clean fracturing fluids that minimize both water usage and formation impairment.In this study,a low-liquid-content viscoelastic surfactant(VES)foam fracturing fluid system was formulated and evaluated through laboratory experiments.The optimized formulation comprises 0.2%foaming agent CTAB(cetyltrimethylammonium bromide)and 2%foam stabilizer EAPB(erucamidopropyl betaine).Laboratory tests demonstrated that the VES foam system achieved a composite foam value of 56,700 mL・s,reflecting excellent foaming performance.Proppant transport experiments revealed minimal variation in suspended sand volume over 120 min across different sand ratios,indicating robust sand-carrying capacity even at high proppant concentrations.Rheological measurements showed that the fluid maintained a viscosity above 120 mPa・s after 120 min of shearing at 70℃ and a shear rate of 170 s−1,with the elastic modulus exceeding the viscous modulus,confirming the system’s exceptional stability and resilience.Furthermore,core damage tests indicated that the VES foam caused only 4.42%formation damage,highlighting its potential for efficient and low-damage stimulation of tight reservoirs.Overall,the findings demonstrate that this low-liquid-content VES foam provides a highly effective,environmentally considerate alternative for hydraulic fracturing in unconventional formations,combining superior proppant transport,rheological stability,and minimal reservoir impairment.展开更多
CO_(2) foam fracturing fluid can effectively integrate CCUS technology into oil and gas field development,and its core advantages include low water consumption,excellent flowback performance,and strong sand-carrying c...CO_(2) foam fracturing fluid can effectively integrate CCUS technology into oil and gas field development,and its core advantages include low water consumption,excellent flowback performance,and strong sand-carrying capacity.For these reasons,it has received increasing attention in the oil and gas field development field.However,this type of fracturing fluid still has some prominent problems:The residue from gel breaking can easily cause formation pollution,the system cost is relatively high,and the utilization rate is low,which forms a significant technical bottleneck.In response to these issues,this study,based on the theory of clean fracturing fluid gel breaking without residue and the reusability of CO_(2)-responsive wormlike micelles,innovatively combines CO_(2)-responsive wormlike micelles with different types of surfactant-based foaming agents to construct a new CO_(2)-responsive foam fracturing fluid system.A systematic performance evaluation of the system was conducted to clarify its defoaming rules under different temperature conditions.Compared with the traditional guar gum CO_(2) foam fracturing fluid,the new system has significant performance advantages.At 90℃,its foam comprehensive value reached 19720 mL·min,6150 mL·min higher than the guar gum fluid.After a 5400 s high-temperature and high-shear test at the same temperature,the residual viscosity of the new system was 67 mPa·s,which is higher than the guar gum fluid.This CO_(2)-responsive foam fracturing fluid simultaneously possesses the application potential of both clean fracturing fluid and foam fracturing fluid.It can effectively solve key problems such as formation pollution and low system utilization rates,and laboratory evaluation experiments confirmed its excellent foaming and rheological properties.These results are of great significance for promoting CO_(2) foam fracturing technology to reach an advanced international level and supporting the low-carbon and highefficiency development of unconventional oil and gas resources in China.展开更多
Microbial polysaccharides,due to their unique physicochemical properties,have been shown to effec-tively enhance the stability of foam fracturing fluids.However,the combined application of microbial polysaccharides an...Microbial polysaccharides,due to their unique physicochemical properties,have been shown to effec-tively enhance the stability of foam fracturing fluids.However,the combined application of microbial polysaccharides and surfactants under high-temperature and high-salinity conditions remain poorly understood.In this study,we innovatively investigate this problem with a particular focus on foam stabilization mechanisms.By employing the Waring blender method,the optimal surfactant-microbial polysaccharide blends are identified,and the foam stability,rheological properties,and decay behavior in different systems under varying conditions are systematically analyzed for the first time.The results reveal that microbial polysaccharides significantly enhance foam stability by improving the viscoelasticity of the liquid films,particularly under high-salinity and high-temperature conditions,leading to notable improvements in both foam stability and sand-carrying capacity.Additionally,scanning electron microscopy(SEM)is used to observe the microstructure of the foam liquid films,demonstrating that the network structure formed by the foam stabilizer within the liquid film effectively inhibits foam coarsening.The Lauryl betaine and Diutan gum blend exhibits outstanding foam stability,superior sand-carrying capacity,and minimal core damage,making(LAB+MPS04)it ideal for applications in enhanced production and reservoir stimulation of unconventional reservoirs.展开更多
文摘As oil and gas development increasingly targets unconventional reservoirs,the limitations of conventional hydraulic fracturing,namely high water consumption and significant reservoir damage,have become more pronounced.This has driven growing interest in the development of clean fracturing fluids that minimize both water usage and formation impairment.In this study,a low-liquid-content viscoelastic surfactant(VES)foam fracturing fluid system was formulated and evaluated through laboratory experiments.The optimized formulation comprises 0.2%foaming agent CTAB(cetyltrimethylammonium bromide)and 2%foam stabilizer EAPB(erucamidopropyl betaine).Laboratory tests demonstrated that the VES foam system achieved a composite foam value of 56,700 mL・s,reflecting excellent foaming performance.Proppant transport experiments revealed minimal variation in suspended sand volume over 120 min across different sand ratios,indicating robust sand-carrying capacity even at high proppant concentrations.Rheological measurements showed that the fluid maintained a viscosity above 120 mPa・s after 120 min of shearing at 70℃ and a shear rate of 170 s−1,with the elastic modulus exceeding the viscous modulus,confirming the system’s exceptional stability and resilience.Furthermore,core damage tests indicated that the VES foam caused only 4.42%formation damage,highlighting its potential for efficient and low-damage stimulation of tight reservoirs.Overall,the findings demonstrate that this low-liquid-content VES foam provides a highly effective,environmentally considerate alternative for hydraulic fracturing in unconventional formations,combining superior proppant transport,rheological stability,and minimal reservoir impairment.
基金supported by the National Natural Science Foundation of China(Grant No.52222403 and U24B2033)Taishan Scholar Program,China(Grant No.tsqn202211079)State Key Laboratory of Deep Oil and Gas,China(Grant No.SKLDOG2024-ZYTS-15).
文摘CO_(2) foam fracturing fluid can effectively integrate CCUS technology into oil and gas field development,and its core advantages include low water consumption,excellent flowback performance,and strong sand-carrying capacity.For these reasons,it has received increasing attention in the oil and gas field development field.However,this type of fracturing fluid still has some prominent problems:The residue from gel breaking can easily cause formation pollution,the system cost is relatively high,and the utilization rate is low,which forms a significant technical bottleneck.In response to these issues,this study,based on the theory of clean fracturing fluid gel breaking without residue and the reusability of CO_(2)-responsive wormlike micelles,innovatively combines CO_(2)-responsive wormlike micelles with different types of surfactant-based foaming agents to construct a new CO_(2)-responsive foam fracturing fluid system.A systematic performance evaluation of the system was conducted to clarify its defoaming rules under different temperature conditions.Compared with the traditional guar gum CO_(2) foam fracturing fluid,the new system has significant performance advantages.At 90℃,its foam comprehensive value reached 19720 mL·min,6150 mL·min higher than the guar gum fluid.After a 5400 s high-temperature and high-shear test at the same temperature,the residual viscosity of the new system was 67 mPa·s,which is higher than the guar gum fluid.This CO_(2)-responsive foam fracturing fluid simultaneously possesses the application potential of both clean fracturing fluid and foam fracturing fluid.It can effectively solve key problems such as formation pollution and low system utilization rates,and laboratory evaluation experiments confirmed its excellent foaming and rheological properties.These results are of great significance for promoting CO_(2) foam fracturing technology to reach an advanced international level and supporting the low-carbon and highefficiency development of unconventional oil and gas resources in China.
基金supported by the Key Technology Research on Increasing Recovery Rate in Tight Sandstone Gas Reservoirs,a Major Scientific and Technological Special Project of China National Petroleum Corporation(Project No.2023ZZ25).
文摘Microbial polysaccharides,due to their unique physicochemical properties,have been shown to effec-tively enhance the stability of foam fracturing fluids.However,the combined application of microbial polysaccharides and surfactants under high-temperature and high-salinity conditions remain poorly understood.In this study,we innovatively investigate this problem with a particular focus on foam stabilization mechanisms.By employing the Waring blender method,the optimal surfactant-microbial polysaccharide blends are identified,and the foam stability,rheological properties,and decay behavior in different systems under varying conditions are systematically analyzed for the first time.The results reveal that microbial polysaccharides significantly enhance foam stability by improving the viscoelasticity of the liquid films,particularly under high-salinity and high-temperature conditions,leading to notable improvements in both foam stability and sand-carrying capacity.Additionally,scanning electron microscopy(SEM)is used to observe the microstructure of the foam liquid films,demonstrating that the network structure formed by the foam stabilizer within the liquid film effectively inhibits foam coarsening.The Lauryl betaine and Diutan gum blend exhibits outstanding foam stability,superior sand-carrying capacity,and minimal core damage,making(LAB+MPS04)it ideal for applications in enhanced production and reservoir stimulation of unconventional reservoirs.
