API RP 13B-1 2019

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