A Comprehensive Review Of The Application Of Nano-Silica In Oil Well Cementing

The oil and gas industry is worth several trillion dollars. In many areas of the oil and gas industry, nanotechnology can bring disruptive improvements. The use of nanotechnology in cement slurry can also provide solutions to some of the oil well cementation challenges. Compared to traditional additives like calcium chloride and silica, nano silica is a safer choice since the volume of nano-silica to be added is minimal compared to calcium chloride and silica.

Silica Gel Desiccant - Free photo on Pixabay

There is a reduction in the thickening time, an improvement in the compressive power, a decrease in porosity and permeability within the cement, and also a decrease in the loss of fluid when nano-silica is applied to the cement slurry. Nano-silica incorporation ensures proper cementation and the well’s greater integrity. Nano-silica helps minimise the waiting period for cement and thus decreases the total cost of capital.

For deep offshore wells where high temperatures and high pressure are often observed, nano-silica is highly recommended. Nano-silica nanoparticles can fill the spaces between the calcium-silicate-hydrate gel particles, acting like a nano-filler. To ensure proper bonding between cement and casing and between cement and forming, it is essential to have good quality cement behind the casing during the completion of a well.

High-quality cement provides the borehole with durability by ensuring the casing is appropriately supported. Fluid channelling results from the low quality of cement behind the casing, and this can result in remedial cementing and therefore increase the time and expense of the cement work. The cement additives such as calcium chloride and silica can affect the exchange of ions and water through the calcium-silicate-hydrates, leading to acceleration or delay in the thickening time of the cement.

Challenges

At present, while drilling wells where low temperatures are encountered, the cement industry faces some challenges. Cement slurry takes longer to set up under these conditions, and there is a subsequent cost increase. Whereas in deep wells where temperatures are too high, early cement hydration leads to early cement setting, resulting in improper cementation and channelling within the cement. The high temperature contained in deep wells causes cement viscosity to decrease, resulting in the loss of fluid.

The primary reason why nanotechnology attracts immediate attention is because of the properties that objects display when nano-scale objects are created. In general, enhancements of nanomaterial induced properties have been observed and reported to include:

  • Growth of strength

  • Increased ratio of tensile to compressive strength over the long term

  • Strengthening viscosity

  • Overall improvements in the compressive power of the early stage

  • Reduction in Cement Thickening Period

Conclusion

Several efforts to reduce the expense of offshore ventures have been used. One such approach is to integrate nano-silica into the cement of oil wells. Nano Silica increases the cement’s compressive strength, decreases the cement’s thickening time, decreases the cement’s porosity and permeability, reduces the channelling inside the cement, etc.

It is highly recommended for well cementing operations because it essentially helps to minimise the period of cement waiting on cement (WOC) to reduce the cost of the rig and thereby reduce the total cost of the well.

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