API RP 13B-2 : 2023

Field Testing Nonaqueous-based Drilling Fluids, Includes ADDENDUM 1, APRIL 2025 and ERRATA 1, OCTOBER 2025

Standard Details

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).