Study On The Preparation And Properties Of New Type Viscous Acid Formulated By Surfanct Or Crosslinked Polymer

Acid treatment is important measure to increase production, theperformance of acid working liquids directly affect the effect of acidtreatments. In order to prepare acid with good performance, new type ofpolymer-free acid and thickened acid has been researched.Polymer-free acid with high viscosity was formulated by 20%HCl, acationic surfactant (FL4-22),and an organic metal surfactant (FL4—22A)with special chemical structure. The corrosion inhibitor(FL4—22B)which is of good compatibility with the retarded acid was prepared. Theeffect of acid composing on performance was studied, and the formulationof the acid (FL polymer—free viscous acid)suitable for formationacidization was recommended. The proterties of FL polymer—freeviscous acid were systematically investigated. It is concluded that thisacid system have good properties in shear stability, corrosioninhibition, and retardance performance. The viscosity of FL polymer—free viscous acid(4%FL4-22+2% FL4-22A+20%HC1+2%FL4-22B) is25mPa·s at 90℃, and rheological studies showed that the acid rapidlydeveloped viscosity as the acid was spent with carbonate minerals, Thishigh viscosity will help in diverting the live acid into otherun-stimulated zones. Once the acid stimulation is complete, the high viscosity of spent acid can be broken either by dilution with theinjection water or crude oil in the reservoir. So this new type of acidsystem can be applied in carbonate acidizing treatments.The water-soluble copolymer P(AM-DMC-AA) of acrylamide (AM),methacryloyloxyethyl trimethyl ammonium chloride (DMC), and acrylicacid (AA) were synthesized by free radical aqueous solutioncopolymerization. The copolymer structures were characterized via IRSpectrum and ~1H-NMR Spectrum. The effects of the reaction conditions suchas pH value, reaction temperature, time, initiator concentration andvarious monomers concentrations on the performance of the copolymersolution were studied.The results show that the conditions of polymerization reaction havenotable effect on the performance of the product. Dissolvability ofcopolymer synthesized in acidity is better than alkalescence. Theintrinsic viscosity and apparent viscosity of copolymer increases atfirst then decreases with monomer concentration, initiatorconcentration increasing and temperature rising. When the AM monomeramount in the copolymer increases, the intrinsic viscosity and apparentviscosity of copolymer increases at first then decreases. IR and ~1H-NMRstructural symptom have been confirmed the copolymer structure unitinclude acrylamide (AM), methacryloyloxyethyl trimethyl ammoniumchloride (DMC), and acrylic acid (AA).The influence factors(water soluble time, copolymer concentration,temperature, shear rate) on Apparent viscosity of the copolymer solutionwere studied. The transmittance at various pH has also been studied, Theshow that P (AM-DMC-AA) has the good water dissolubility and thicknessability; The apparent viscosity of copolymer solution decreased withshear rate and temperature increase. Iransmittance study showed that P(AM-DMC-AA) has distinct characteristic of zwitterion copolymer.The rheology, heat stability, shear stability of copolymerP(AM-DMC-AA) as viscosifier also were evaluated. The results show that the thickened acid has good properties of acid dissolubility, heatstability, shear stability, can be applied in acidizing treatments.Crosslinked acid has been prepared by cross-linker; The mechanismof cross-linker and P(AM-DMC-AA)has been studied; The apparent viscositychanges of crosslinked acid in different temperature, cross-linkerconcentration, copolymer concentration and AMcontent in P (AM-DMC-AA)were investigated. Characteristic evaluate of Crosslinked acid indicatethat crosslinked acid has good propertis of retardance performance. Theapparent viscosity and residue content of liquids after gel-breakingaccord with pertinent standard.