Page 193 - Shale Shakers Drilling Fluid Systems

176 SHALE SHAKERS AND DRILLING FLUID SYSTEMS

Experimental and calculation procedure:

A sample of discard is placed in a 40.10 gm crucible and weighed:

Crucible + Sample Weight = 114.94 gm

The wet sample weight is 74.84 gm. Since the wet discard density is 1.77 gm/cc, the wet sample has a volume of
74.84 gm/1.77 gm/cc = 42.19 cc.

After heating overnight at 250°F, the crucible and sample weight is 91.08 gm. The dry solids weight in the sample is:
91.8 gm - 40.10 gm = 50.98 gm

The dry solids weight percent in the discard is the weight of dry solids divided by the wet sample weight times 100 or:

[(50.98 gm)/74.84 gml x 100 = 68.11 wt%

The volume of the dry sample is calculated by subtracting the volume of water lost from the volume of the wet sample:
the 42.19 cc wet sample lost 114.94 cc - 91.08 cc or 23.86 cc of water. The volume of the dry sample is:

42.19 CC - 23.86 CC = 18.33 CC

The density of the dry solids is the weight of dry solids divided by the volume of dry solids, or 50.98 gm/18.33 cc or
2.78 gm/cc.

CALCULATION OF BARITE DISCARD 2. The volume of low-gravity solids is the total
volume of dry solids minus the volume of
Assuming that all of the drilled and other low- barite.
gravity solids in the drilling fluid have a dried 3. The volume of low-gravity solids in one cc
density of 2.47 gm/cc and the barite has a den- of solids = 1 cc minus the volume of barite
sity of 4.2 gm/cc, the weight percent of barite in in 1 cc of solids.
the dry sample may be calculated from the follow-
ing mass-balance equation: This can be expressed as follows:

or

To determine the terms on the right side of
the equation:
This equation may be reduced to the expression:
1. The volume of barite is the density (4.2 gm/cc)
divided by the weight of barite D = 0.4119W R + 2.47
D