Cationic Acrylamide Copolymers Research Articles

Effect of Additives on the Acid Dissolution Rates of Calcium and Magnesium Carbonates

Summary A rotating-disk instrument was used to measure the dissolution rates of both calcite and dolomite rock samples in HCl solutions. The results of more than 60 experiments are reported in this paper. The effect of common acidizing additives on the rock dissolution rate is measured for different acids containing quaternary amines, polymer, surfactant, mutual solvent, iron-chelating additive, and dissolved iron. Measurements are made at 23 and 50°C for calcite and dolomite marble samples. Marble samples from Turkey, Greece, and Italy were analyzed to find suitable reference materials. Marble composed of 100% calcite (calcite marble) as well as 91% dolomite (dolomite marble) was used and compared very well with previously published results. Results of rock dissolution rates with common acidizing additives showed significant differences. 1.5 vol% cationic acrylamide copolymer decreased the calcite and dolomite dissolution rates significantly. At 1,000 rpm, the calcite dissolution rate with 1.5 vol% polymer and 0.1 M (0.36 wt%) HCl had a value that was 11.4% of the value measured with 0.1 M of HCl alone. Polymer changed the acid/rock reaction from mass-transfer-limited to surface-reaction-limited with both calcite and dolomite. This surface effect is possibly caused by polymer adsorption. 10 vol% mutual solvent increased the acid dissolution rate by 9% for calcite and by up to 29% for dolomite. 5000 mg/L iron (III) resulted in surface deposition of iron (III) hydroxide for both calcite and dolomite. At low rotational speeds, this surface layer had an inhibiting effect on the dissolution rate. 2 vol% corrosion inhibitor decreased the calcite dissolution rate by approximately 9%. Citric acid at 12 g/L decreased the calcite dissolution rate by an average of 9%, possibly because of the formation of calcium citrate at the surface. 0.2 vol% nonionic surfactant had no significant effect on the acid dissolution rate of calcite.

Sedimentation Kinetics of Bentonitic Clay Suspension as Influenced by pH of the Medium, Chemical Nature and Concentration of Surfactants, and Molecular Properties of Cationic Acrylamide Copolymer Flocculants

The kinetics of flocculation of bentonitic clay suspensions and thickening of the sediments was studied in the modes of free and hindered sedimentation as influenced by pH of the medium, chemical nature and concentration of surfactants, and molecular properties of cationic flocculants, random copolymers of acrylamide with dimethylaminoethyl methacrylate hydrochloride.

Flocculation kinetics of an ochre suspension in salt(NaCl)-containing aqueous media in the presence of anionic and cationic acrylamide copolymers

The sedimentation kinetics of an ochre suspension in salt (NaCl)-containing aqueous media was studied in the presence of ionogenic (anionic, A, and cationic, C) acrylamide copolymers with high molecular weight (M > 2 × 106) using a VT–0.5 torsion balance. The ionic strength of the dispersion medium varied in the wide range from 0.001 N to 0.4 N. The flocculation proceeded predominantly by a `bridge' mechanism, and the fraction of macromolecules inactive in the acts of floccule formation was significantly higher for C copolymer as compared with A copolymer. A drastic fall in the flocculating activities of A and C copolymers when passing from salt-free to salt-containing media is caused mainly by two following events:

Improved treatment of acrylamide co- and terpolymers for water control in gas-producing and storage wells

The main objective of this study was to determine the optimal conditions for application of acrylamide co- and terpolymers for water control in gas wells under various environmental conditions. Starting in February 1992, the limits of application of acrylamide co- and terpolymers were first defined in the laboratory through extensive tests. Based on the results of the comparative feasibility study, four field tests were performed in both gas reservoir and underground gas storage wells. This paper presents the latest results of field tests. Using a partially sulfonated acrylamide terpolymer, the first field test was performed in January 1993 on an abandoned gas-producing well with a BHT of about 130°C, an average matrix permeability of 0.01 μm 2 and a produced brine salinity of more than 300 g/l TDS. The second test was performed in a well from a gas storage field with a temperature of about 87°C, an average permeability of 0.06 μm 2 and a produced brine salinity of more than 270 g/l. Based on the information provided from the first field test and the feasibility study performed for this well, a lower molecular weight partially sulfonated acrylamide terpolymer was finally used for this test. Using a cationic acrylamide copolymer, the third field test was performed in a low-temperature, high-brine-salinity gas storage well with BHT of 30°C and brine salinity of 218 g/l. Based on the excellent results of the third field test, the same polymer was selected for the last water shut-off treatment in a low-temperature gas storage well with a matrix permeability ranging from 0.04 to 3.6 μm 2. Since the treatment, the gas well and the gas storage wells have exhibited improved production performances.

Evaluation of chemical structural heterogeneity of cationic acrylamide copolymers by high-performance liquid chromatography

The chemical structural heterogeneities of two cationic acrylamide copolymers, methacryloxyethyl trimethylammonium chloride—acrylamide (AAM) and diallyldimethyl ammonium chloride—AAM, have been determined by high-performance liquid chromatography. In this method aqueous size-exclusion chromatography is combined with ion-exchange chromatography. Gradient elution with a sodium chloride solution is used. The resulting chromatogram shows the heterogeneity between polymer chains in solution. A comparison of the chromatograms of the original copolymer and its degradation product showed the heterogeneity along the copolymer chains.

Adsorbing Colloid Flotation of Zn(II) with Fe(OH)(3) and Polyelectrolytes

Abstract It was found that zinc ion could be removed from aqueous solutions by adsorbing colloid flotation with Fe(OH)3 and sodium lauryl sulfate (SLS) provided that the ionic strength of the solution is low (containing no greater than 0.02 M NaNO3). An excess dose of iron resulted in poor separation. Three types of polyelectrolytes were used as the activators to compensate for the effect of increasing ionic strength of the solutions. Betz 1150 (a weakly cationic acrylamide copolymer) was found to be the most effective activator. The separation was effective from a solution containing NaNO3 as high as 0.7 M when Betz 1150 was used as the activator.

Instability of aqueous solutions of cationic acrylamide copolymers

Instability with time in aqueous solutions of cationic acrylamide copolymers has been studied by viscometry. The ageing effect is manifest to a higher degree for solutions of lower concentration and for copolymers with a higher content of acrylamide units. The introduction of NaNO 3 into freshly prepared aqueous solutions of the copolymers stabilizes the viscosity of the system. The absence of change in the viscosity of dilute solutions of the copolymers in 1 m NaNO 3 obtained from aqueous solutions at different stages of ageing excludes the degradation mechanism of their instability.