Formation And Performance Of Long Chain Tertiary Amine Salt/High Molecular Weight Polyethylene Oxide Hydroge

The hydrogels were applied in tertiary oil recovery as thickeners currently, and cross-linked polyacrylamide mostly as thickener, but it takes long time to dissolve in field application, thus inconvenient to use. In this study, prepared a long-chain tertiary amine salts/macro-molecular weight polyethylene oxide (shorted as PEO) hydrogel fracturing fluid with hugemarket potential, blended by erucamide propyl-N,N-dimethyl amine salt micelles and PEO polymer. It has many advantages, such as, dissolved fast, prepared simply, easy to control and less residue of gel breaking, and so on.Erucamide propyl-N,N-dimethyl amine salt(abbreviated as PKOH) was prepared in two steps. Firstly, erucamide propyl-N,N-dimethyl amine(shorted as PKO) was synthesized by erucic acid and N, N-dimethyl-1,3-propanediamine. Secondly, treated PKO by acetic acid, and obtainedlong-chain tertiary amine salts of PKOH, which was a soluble surfactant, and its cmc value was 7.5×10-5mol L-1, and measured by surface tension, fluorescence spectroscopy, ultraviolet absorbance and dynamic light.In order to get a liquid surfactant PKOH thickener system, ethylene glycol monomethyl ether was used as depressantto liquefaction PKOH. Tested pH value, concentration, shear rate and temperature affect viscosity behavior of PKOH thickener systems, and examinated storage modulus G' and loss modulus G". Results showed that the PKOH thickener hydrogel was a shear-thinning non-Newtonian fluid, and it was used in weakly acidic environment, displayed good elasticity and well shear recovery performance of water-based gel system.The relationship amongmolecular weight, concentration, temperature, shear rate of soluble polymer PEO and viscosity behavior of PEO solution were discussed, and storage modulus G'and loss modulus G" were tested. The results showed that, PEO solution was part of pseudoplastic fluid, and it displayed apparent shear thinning at high shear rate and a larger concentrations, and it had less viscoelasticity. In viscous fingering model, concentration of PEO solution, temperature and salt concentration influenced viscous fingering phenomenon were studied, PEO played significant role in fracturing fluid flowing.The effect of PEO content, PKOH thickener content, potassium content on the viscosity of PKOH/PEO fracturing fluid were tested, and screened out better fracturing fluid formulation was 3% PKOH thickener and 0.2% PEO and 2% KCl by fitting test. Its viscosity about 260 mPa.s at room. The rheological properties of PKOH/PEO fracturing fluid was characterized by shear rate, shear time and temperature as well as viscoelastic.The results presented that, PKOH/PEOfracturing fluid also belonged to shear thinning fluid. Storage modulus G' and loss modulus G" were 7 Pa and 1 Pa respectively. The application performance of PKOH/PEO fracturing fluid was indicated by temperature and shear resistance, suspension of sand, gel breaking and core damage. It revealed that, the viscosity of the fracturing fluid maintained over 90 mPa.s, in 80? and 170 s-1 shear 90 min, and well suspension sand. Viscosity of gel breaking solution was below 5mPa.s, residue content about 50 mg L-1, surface tension and interfacial tension were 23.88 mN m-1 and 0.0246 mN m-1 respectively, diameter of residue was 40 nm at average. Core damage rate was about 11%. These performances all met the construction requirements.