API RP 13B-2

This recommended practice provides standard procedures for determining the following characteristics of nonaqueous drilling fluids (NADFs):
• drilling fluid density (mud weight);
• viscosity and gel strength;
• filtration;
• nonaqueous fluid (NAF), water, and solids concentrations;
• alkalinity, chloride concentration, and calcium concentration;
• electrical stability (ES);
• lime and calcium concentrations, calcium chloride, and sodium chloride concentrations;
• low-gravity solids and weighting material concentrations;
• sand content;
• high-temperature, high-pressure (HTHP) filtration using the permeability plugging apparatus (PPA).