US Patent 7618927 Increased rate of penetration from low rheology wellbore fluids

A method of increasing a rate of penetration when drilling as compared to drilling with a baseline drilling fluid comprising an API-grade barite weighting agent and having a given sag, settling rate, density, flow rate, and pressure drop through a wellbore, comprising: circulating a drilling fluid comprising a base fluid and a micronized weighting agent through the wellbore; wherein the drilling fluid is characterized as having an equivalent density, an equivalent or lower settling rate, and an equivalent or lower sag than the baseline drilling fluid; wherein the circulating is at a higher flow rate than the baseline drilling fluid flow rate; and wherein the circulating results in an equivalent or lower pressure drop through the wellbore.