OVERVIEW

Low-gravity solids in a drilling fluid may be calculated from the equation below:

where

• ? _f = density of filtrate, g/cm3

• ? _B = density of barite, g/cm3

• ? _LG = density of low-gravity solids, g/cm ³

• ? _o = density of oil, g/cm3

• V _S = volume percentage of suspended solids

• V _o = volume percentage of oil

• MW = mud weight, ppg

The density of the filtrate may be calculated from the equation:

where

• [NaCl] = concentration of NaCl in filtrate, mg/L

• [KCl] = concentration of KCl in filtrate, ppb

• [CaCl ₂] = concentration of CaCl ₂ in filtrate, mg/L

• [MgCl ₂] = concentration of MgCl ₂ in filtrate, mg/L.

The total suspended solids, V _s, may be calculated:

where V _w is the volume percentage of water.

Low-gravity solids calculated by the equation include bentonite. The quantity of drilled solids in the drilling fluid would be the difference between the volume percentage of (%vol) low-gravity solids and the %vol bentonite.

For freshwater drilling fluids, assuming that the density of low-gravity solids is 2.6 and the density of barite is 4.2, the equation becomes

A 12.0-ppg drilling fluid with 20% volume of solids would contain 12.5% volume of low-gravity solids:

The retort is normally used to determine the volume percent solids in a drilling fluid.

3.1 PROCEDURE FOR A MORE ACCURATE LOW-GRAVITY SOLIDS DETERMINATION

This procedure...