Figure 1: types of gel strengths in muds (source: Oilfield Glossary,
2014)
The gel strength is calculated using the 3-rpm reading, which is
recorded after the mud sample, has been stirred at 600 rpm using a
viscometer. The first reading is usually a 10 second reading while the
second is usually 10 minutes. If a third reading is to be taken, it
would usually be measured at 30 minutes and this is because this reading
will inform us about the amount of gel the mud sample would experience
when exposed to excessive static periods [2]. A drilling mud
circulation system with high gel strength will require a high pump
pressure to break circulation when the mud has been inert for a long
time. Some of the factors that contribute to a high gel strength value
in a drilling mud system are over treatment with carbon-based gelling
substances and a build-up of fine particles of solids in the mud