SALT DEPOSIT DISSOLUTION TECHNOLOGY: SCIENTIFIC BASIS FOR SELECTING CHELATING AND CONVERSION FORMULATIONS

The article analyses the technology of chemical dissolution of carbonate and sulfate salt deposits by comparing published experimental data, recalculating the composition of the Chegara field formation water into equivalent form and performing a stoichiometric assessment. It is shown that the Chegara water is of the calcium chloride type (rNa/rCl = 0.85) with a total divalent cation content of 170 mmol/L, so that a 0.5 M chelating dissolver prepared with this water loses ≈34 % of its capacity. It is substantiated that the K4-EDTA + K2CO3 system (pH 10.5) is more effective for calcium sulfate and catalysed DTPA systems for barium sulfate, while biodegradable MGDA and GLDA outperform DTPA and HEDP in gypsum dissolution. A six-stage process scheme is proposed.