What is the main functional mechanism of inorganic additives used in drilling fluids?

Inorganic additives mostly are water soluble inorganic alkaline and salt type. Most of them can provide cation and anion. And some of them can form gel with water or generate complex. The functional mechanism in drilling fluid can be summarized as the following aspect.
1. Ion exchange adsorption. Mainly Exchange Na+ between Ca2+ with clay particle surface. The process can improve the performance of clay mud, prepare calcium treatment drilling fluid and anti-collapse, take a big influence with the performance of drilling fluids.
2. Control PH value of drilling fluids. Add suitable caustic soda or other inorganic additives are the brief way to adjust PH value.
3. Precipitation effect. When to calcium and magnesium invade into drilling fluids, it can weaken clay’s hydration and dispersant ability and damage performance. Firstly add suitable caustic soda to remove magnesium, and then add suitable sodium carbonate to remove calcium.
4. complexation effect. It can effectively remove polluted ion like calcium and magnesium etc. when use lignite alkaline lye or FCLS or other treatment additives, it can also improve resistant high temperature performance.
5. Mix with organic treatment additive can generate soluble salt.
6. Soluble inhibition effect.

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