OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: 832-320-7300 / Fax: 713-880-9886 / www.ofite.com
18
Reporting
Data
1. The filtrate volume collected should be corrected to a filter area of 7.1 in
2
(4580 mm
2
) so the amount collected will have to be doubled.
2. The spurt loss is defined as the amount of mud and/or filtrate recovered
from the collector immediately after the differential pressure is applied
until the flow of fluid through the permeable disc stops and gas from the
receiver blows out freely. The presence of whole mud in the spurt indi-
cates that there was not an immediate seal of the mud when it passed
through the filter. In most cases, the goal is to eliminate or minimize the
amount of whole mud in the spurt and in the 30 minute test.
3. After the test is complete, remove the ceramic disk from the test cell and
wash it very lightly with base fluid. Measure the filter cake thickness to
the nearest
1⁄32
" (0.8 mm). Although cake descriptions are subjective, such
notations such as hard, soft, tough, rubbery, firm, etc. may convey impor-
tant information of cake quality.
Permeability Plugging Test Volume
V
PPT
= 2 × V
30
Where:
V
PPT
= Permeability Plugging Test Volume
V
30
= Filtrate volume after 30 minutes
Spurt Loss
V
1
= 2 ( 2V
7.5
- V
30
)
Where:
V
1
= Spurt Loss
V
7.5
= Filtrate volume after 7.5 minutes
Static Filtration Rate
V
SF
= 2 ( V
30
- V
7.5
) / 2.739
Where:
V
SF
= Static Filtration Rate (velocity of flow)
Calculations
