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Nano-silica's Effect on fluid loss

wallpapers News 2021-07-16
In cementing operations, loss of water can adversely affect the performance of slurry and can lead to improper cementation. It is necessary to add a chemical additive to control the loss of fluid to the formation through filtration. For more than 20 years, fluid loss control agents have been added to cement slurries it is generally acknowledged that a lack of fluid loss control may be responsible for primary cement failures.
When cement slurry samples with different amounts of nano-silica were observed, the results showed that as the percentage of nano-silica in the cement slurry increased, the fluid loss decreased. Slurry with 1% nano-silica reported a decrease in fluid loss up to 43%. Similarly, with an increasing amount of nano-silica, a gradual decrease in fluid loss was observed.
It is evident from the previous discussion that the incorporation of nano-silica in cement slurry reduces the pore size. Pores of smaller size lose lesser water and hence fluid loss is alleviated. The fine particles of nano-silica are well placed between empty pores of cement matrix and do not allow the solid phase of slurry to be separated from the liquid, hence water in the slurry cannot leave the cement matrix and as a result, there is a reduction in the fluid loss.
Fluid loss in mud infused with nano-silica increases as the concentration of nano-silica increases. The excessive amount of nano-particle does not have the ability to fill the tiny pores present in the mud cake because of which generates a very high fluid loss.
Nano-silica activates pozzolanic reaction, resulting in enhancement of durability of cement. Nano-silica is an attractive technology because it mitigates the possibility of costly cement repair jobs. But not every technology is one hundred percent perfect and accurate. Despite its impeccable benefits, nano-silica suffers some minor drawbacks. From the Indian perspective, the cost of purchasing nano-silica can be a deciding factor but as far as the global scenario is concerning cost is not of much concern. Besides from the economic point of view, nano-silica can unnecessarily increase the viscosity at a required slurry density. Nano-silica can cause pumpable and air entrainment issues. The other problem that is faced is the inability to determine how much quantity of nano-silica should be added to the cement to achieve the greatest performance. Some literature reports that the quantity should be 1% by weight of cement (BWOC) whereas some literature recommends at least 2% to achieve better performance.