Geopolymer based Oil Well Cementing Systems using Silica Fume

Nowadays, ordinary Portland cement is used extensively in the well cementing
operations, due to its low cost and widespread availability of limestone, clay and
shale. However, there are two big challenges presented with the usage of Portland
cement for oil well cementing purpose, one is the occurrence of cement failure while
the other one is the vast emission of carbon dioxide. The objective of this project is
to develop geopolymer based oil well cementing systems by utilizing silica fume, as
a better substitute for the current conventional Portland cement. Throughout the
project, five types of cement slurries are prepared and laboratory tests are carried out
to test their rheology properties, filtration loss and compressive strength. All these
tests were carried out at a pressure ranging from 1000 psi to 3000 psi with varied
temperatures (100¢ªF, 150¢ªF and 200¢ªF), representing different oil well conditions.
The test results show that the developed geopolymer cements appear to be in ideal
plastic viscosity range while geopolymer cements with 20% and 30% of silica fume
perform well in term of yield point. As for filtration loss, geopolymer cements with
10%, 20% and 30% of silica fume exhibit desired readings at temperature of 150 ¢ªF.
Silica fume is proved to have a significant effect in improving compressive strength
and the geopolymer cement with 30% of silica fume is the cement slurry with
optimum performance. It is also found out that the developed geoplymer cements
with silica fume are suitable to be used at low and medium temperature oil wells.
Overall, geopolymer based oil well cementing systems using silica fume have better
physical and mechanical properties compared to conventional Portland cement.