On the basis of analysis on literatures at home and abroad,the composition and advantages of clean foam fracturing fluid are described,and the current researches on its stability,rheology,proppant carrying property an...On the basis of analysis on literatures at home and abroad,the composition and advantages of clean foam fracturing fluid are described,and the current researches on its stability,rheology,proppant carrying property and low damage property are analyzed in detail.The clean foam fracturing fluid,composbd by viscoelastic surfactant,salt solution,foaming agent and gas,is prospectivefor developing unconventional oil and gas resources.This system shows strong proppant carrying capacity,low fluid loss,high fractu-ring effects,strong flowback capacity,and small formation damage,by combining the advantages of clean fracturing fluid and foamfracturing fluid.It has become a focus of fracturing fluids in recent years.Some samples are provided to demonstrate the field appli-cation results of the clean foam fracturing fluid,which further indicates that the system can improve oil well productivity with nodamages to formations.Finally,in view of formula system,foam stabilization mechanism and supporting operation processes,theprospects of clean foam fracturing fluid is pointed out.展开更多
Taking stearic acid as the raw material,N-(2-(dimethylamino)ethyl)stearamide(C18N2N)was synthesized.A new surfactant was prepared by mixing C18N2N and cinnamic acid(TA)with fixed ratio.This surfactant was formed by no...Taking stearic acid as the raw material,N-(2-(dimethylamino)ethyl)stearamide(C18N2N)was synthesized.A new surfactant was prepared by mixing C18N2N and cinnamic acid(TA)with fixed ratio.This surfactant was formed by noncovalent electrostatic interactions,which avoided complicated synthetic procedures.The surface activity and rheological properties of the surfactant were investigated with a surface tensiometer and a rheometer.The critical micelle concentration(cmc)and the surface tension at cmc(γ_(cmc))of the surfactant were 0.11 mmol/L and 32.4 mN/m,indicative of strong aggregation and adsorption ability.The maximum amount adsorbed(Γ_(max))and the minimum molecular area occupied(A_(min))were 2.77μmol/m^(2)and 0.6 nm^(2).Wormlike micelles were formed at the concentration of 25 mmol/L.When the concentration was over 100 mmol/L,the zero-shear viscosity(η_(0))abruptly increased and then reached the maximum value for the surfactant of C18N2N/TA containing 150 mmol/L TA.The solution viscosity was as high as 1761.38 Pa·s.The effects of temperature on the rheological behavior were also considered.With the increase of temperature,the viscosity gradually increased.And when the temperature reached 40℃,η_(0)of the solution with the concentration of 100 mmol/L achieved the maximum value of 1370.386 Pa·s.When the temperature continued to rise,η_(0)began to decrease with further increasing temperature.A remarkable viscosity of 305.55 Pa·s was still remained at 50℃.The viscoelastic solutions showed good temperature resistance and shear resistance.The surfactant solutions applied as the fracturing fluid were also investigated.This surfactant also showed excellent sand-carrying performance,and the settling rate of the sand was merely 0.26 cm/min.This surfactant could be simply prepared and showed excellent performance,which expanded the preparation and application field of novel surfactants.展开更多
文摘On the basis of analysis on literatures at home and abroad,the composition and advantages of clean foam fracturing fluid are described,and the current researches on its stability,rheology,proppant carrying property and low damage property are analyzed in detail.The clean foam fracturing fluid,composbd by viscoelastic surfactant,salt solution,foaming agent and gas,is prospectivefor developing unconventional oil and gas resources.This system shows strong proppant carrying capacity,low fluid loss,high fractu-ring effects,strong flowback capacity,and small formation damage,by combining the advantages of clean fracturing fluid and foamfracturing fluid.It has become a focus of fracturing fluids in recent years.Some samples are provided to demonstrate the field appli-cation results of the clean foam fracturing fluid,which further indicates that the system can improve oil well productivity with nodamages to formations.Finally,in view of formula system,foam stabilization mechanism and supporting operation processes,theprospects of clean foam fracturing fluid is pointed out.
文摘Taking stearic acid as the raw material,N-(2-(dimethylamino)ethyl)stearamide(C18N2N)was synthesized.A new surfactant was prepared by mixing C18N2N and cinnamic acid(TA)with fixed ratio.This surfactant was formed by noncovalent electrostatic interactions,which avoided complicated synthetic procedures.The surface activity and rheological properties of the surfactant were investigated with a surface tensiometer and a rheometer.The critical micelle concentration(cmc)and the surface tension at cmc(γ_(cmc))of the surfactant were 0.11 mmol/L and 32.4 mN/m,indicative of strong aggregation and adsorption ability.The maximum amount adsorbed(Γ_(max))and the minimum molecular area occupied(A_(min))were 2.77μmol/m^(2)and 0.6 nm^(2).Wormlike micelles were formed at the concentration of 25 mmol/L.When the concentration was over 100 mmol/L,the zero-shear viscosity(η_(0))abruptly increased and then reached the maximum value for the surfactant of C18N2N/TA containing 150 mmol/L TA.The solution viscosity was as high as 1761.38 Pa·s.The effects of temperature on the rheological behavior were also considered.With the increase of temperature,the viscosity gradually increased.And when the temperature reached 40℃,η_(0)of the solution with the concentration of 100 mmol/L achieved the maximum value of 1370.386 Pa·s.When the temperature continued to rise,η_(0)began to decrease with further increasing temperature.A remarkable viscosity of 305.55 Pa·s was still remained at 50℃.The viscoelastic solutions showed good temperature resistance and shear resistance.The surfactant solutions applied as the fracturing fluid were also investigated.This surfactant also showed excellent sand-carrying performance,and the settling rate of the sand was merely 0.26 cm/min.This surfactant could be simply prepared and showed excellent performance,which expanded the preparation and application field of novel surfactants.
