Changes

Calcium chloride brine is incompatible with formation or injection brines containing CO_3^2-, HCO_3^-, or SO_4^2-. Consequently, scale inhibitor must be used or a suitable (normally higher concentration and more costly) substitution of KCl or NH₄Cl brines will suffice. Another alternative is to displace the noncompatible water with a slug of KCl or NH₄Cl and follow this with CaCl₂.

Calcium chloride brine is incompatible with formation or injection brines containing CO_3^2-, HCO_3^-, or SO_4^2-. Consequently, scale inhibitor must be used or a suitable (normally higher concentration and more costly) substitution of KCl or NH₄Cl brines will suffice. Another alternative is to displace the noncompatible water with a slug of KCl or NH₄Cl and follow this with CaCl₂.

The contact of calcium or potassium fluids with low concentration, spent HF acid used for [[stimulation]] of sandstones will also form damaging precipitates. NH₄Cl can be used to displace spent HF acid several feet into the formation prior to CaCl₂ or KCl treatment, thereby preventing acid reaction with Ca²⁺ or ''K''⁺. Conversely, HF acid should not be allowed to contact calcium-bearing minerals such as calcite or dolomite. It is necessary to use HCl as a preflush or cation exchange Ca with an NH₄Cl preflush. Only underreaming or fracturing will correct calcium fluoride precipitate damage.

The contact of calcium or potassium fluids with low concentration, spent HF acid used for [[stimulation]] of sandstones will also form damaging precipitates. NH₄Cl can be used to displace spent HF acid several feet into the formation prior to CaCl₂ or KCl treatment, thereby preventing acid reaction with Ca²⁺ or ''K''⁺. Conversely, HF acid should not be allowed to contact calcium-bearing minerals such as calcite or [[dolomite]]. It is necessary to use HCl as a preflush or cation exchange Ca with an NH₄Cl preflush. Only underreaming or fracturing will correct calcium fluoride precipitate damage.

===Rate of salinity change===

===Rate of salinity change===