Scientists from Russia, Iran, and Austria have developed a new composition of lightweight cement that is 18% cheaper than traditional foam cement, according to the press service of Tomsk Polytechnic University (TPU). The development is intended for use in unconventional oil and geothermal wells.
Drilling such wells often poses problems: wall subsidence, underground pressure, and the appearance of cracks. Cementing helps isolate the formation and prevent resource loss. The new cement slurry is pumped into the space between the casing string and the formation, which strengthens the well walls and increases the service life of the equipment.
The new cement contains a graphene nanohybrid — aluminum oxide created by co-precipitation, as well as hollow glass microspheres and traditional additives to reduce density. The graphene nanohybrid increases the heat resistance and critical strength of the cement stone at high temperatures, improves the density of the solution, water loss, and thermal conductivity.
According to Shadfar Davoudi, a research engineer at the Heriot-Watt TPU Center, the cost of the new cement is lower than that of foamed or composite cement with glass microspheres. In addition, the new composition avoids the technological problems of conventional lightweight cement, including changes in density under pressure and the need for complex nitrogen injection systems.
The development has already shown promising mechanical, thermal, and rheological properties and can be used in hot and low-reservoir geothermal wells at different temperatures. The research results are published in the journal Construction and Building Materials.
The use of new lightweight cement can reduce drilling costs, increase production efficiency, and extend the life of wells, which is especially important for working with unconventional oil and geothermal energy resources.