API RP 13B-1

This recommended practice provides standard procedures for determining the following characteristics of water-based drilling fluids:

a) drilling fluid density (mud weight);
b) viscosity and gel strength;
c) filtration;
d) water, oil, and solids contents;
e) sand content;
f) methylene blue capacity;
g) pH;
h) alkalinity and lime content;
i) chloride content;
j) total hardness as calcium;
k) low-gravity solids and weighting material concentrations.

Annexes A through K provide additional test methods that may be used for:

• chemical analysis for calcium, magnesium, calcium sulfate, sulfide, carbonate, and potassium;
• determination of shear strength;
• determination of resistivity;
• removal of air;
• drill-pipe corrosion monitoring;
• sampling, inspection, and rejection;
• rig-site sampling;
• calibration and verification of glassware, thermometers, timers, viscometers, retort cup, and drilling fluid balances;
• permeability plugging testing at high temperature and high pressure for two types of equipment;
• sag testing.