The prediction of mineral solubilities in natural waters: A chemical equilibrium model for the Na-Ca-Cl-SO4-H2O system, to high temperature and concentration

Modelling of calcium sulphate solubility in concentrated multi-component sulphate solutions

Mechanism and kinetics of gypsum–anhydrite transformation in aqueous electrolyte solutions

Development of an MSE-based chemical model for the solubility of calcium sulphate in mixed chloride–sulphate solutions

The solubility of gypsum and anhydrite in simulated laterite pressure acid leach solutions up to 250 °C

The solubility of anhydrite in several aqueous salt solutions has been determined for temperatures between 250/sup 0/ and 325/sup 0/C and at pressures just above the vapor pressure. The data obtained are intended to be of practical interest in connection with scale precipitation in field heaters during wet steam or hot water injection for thermal oil recovery. The salt solution used contained such electrolytes as sodium chloride, sodium nitrate, calcium chloride, magnesium chloride, sodium sulfate, and magnesium nitrate. Solubility data are determined for a number of binary, ternary, and quarternary systems. (25 refs.)

Solubility of anhydrite in several aqueous salt solutions between 250.degree. and 325.degree.

A key step in feed water treatment for the generation of wet steam for thermal oil recovery is the removal of calcium and magnesium hardness by cation exchange series softening A knowledge of the solubility of any scale- forming salts in brines at elevated temperatures is necessary for fixing the level to which the feed water must be softened Solubility data for calcium sulfate, previously not available above 200$C pi392$F/sup -/, were determined in a flow equilibrium apparatus These data have been used to develop a scheme for predicting the solubility of anydrite in hot water or steam droplets for saturated steam pressures as high as 2,000 psig pi336$C, 736$F/sup -/ The calcium sulfate solubility product is represented by a combination of 2 factors, one reflecting the effects of ionic strength an the other accounting for the effects of complex ion formation in either calcium- rich or sulfate-rich brines The scheme is applied to a calcium-rich brine from a pilot hot-water flood and to several sulfate-rich feed waters an blowdown (cooled steam droplets) samples from steam soak operations The predicted calcium hardness levels corresponding to the calcium sulfate solubilities agreed reasonably well with the results of laboratory solubility determinations runmore » on the field samples« less

Jane C. Rodgers

Papers

Solubility of anhydrite in several aqueous salt solutions between 250.degree. and 325.degree.

Prediction of Anhydrite Precipitation in Field Water-Heating Systems