The article presents an overview of the most well-known carbon materials to date and an analysis of their effect on various physical and mechanical properties of grouting compounds made of ordinary Portland cement.
Currently, cement modifiers are widely used, the addition of which increases the strength characteristics of cement stone – compressive and bending strength, reduces the strength gain time and at the same time slows down the primary setting, reduces moisture absorption, increases frost resistance, etc.
The problem of increasing the efficiency of the well creates the need for high-quality cementing and interlayer insulation. To increase the strength and reduce the permeability of cement stone, as well as fastening the trunk of an oil and gas well, constant development of new technologies with the use of improved additives in grouting compositions is required. To maintain the operational characteristics of the well, prevent the destruction of the integrity of its trunk, increase tightness, and comply with environmental requirements, various modifiers satisfying drilling conditions are introduced into cements.
To date, a significant amount of proven graphite reserves is concentrated in Russia. The availability of the material for industry is quite high.
Starting from graphene and carbon nanotubes (CNTs) and ending with graphite, carbon compounds have different effects on the properties of cement stone. A few years ago, a two–dimensional modification of carbon, graphene, was discovered. The innovative material significantly influenced the development of science and technology in subsequent years.
The analyzed, experimentally obtained results of world research on the introduction of carbon materials into grouting mixtures showed the ambiguity of the influence of graphite and its derivatives on the quality of cement stone, and also indicated the absence of a unified theory of the influence of carbon derivatives on such.
Today, the carbon atom is the main building material for dozens of known and hundreds of unexplored organic substances. From natural graphite to diamond and from technical soot to fullerenes, this amazing element of the periodic table is being actively introduced into the oil and gas industry. Despite the fact that all these materials consist of exactly the same carbon atoms, their properties can vary radically.
It is difficult to imagine life without graphite pencils, jewelry and technical diamonds, solar panels, fire-fighting equipment, medicines and other carbon applications. The fields of application of carbon materials in drilling are aimed at improving the lubricating properties of drilling fluid, creating anticorrosive coatings of metal products, highly efficient cementing of wells, surface reinforcement of rock-crushing tools, separation of water from oil, cleaning from oil spills, etc. [1].
Figure 1 shows representatives of the amazing carbon family – eight of its allotropic modifications.
FIG. 1. Modern eight allotropic carbon modifications:
а) Diamond, b) Graphite, c) Lonsdaleite, d) С60 (fullerenes), e) С540, f) С70,
g) Amorphous carbon, h) Single-layer carbon nanotube
Despite the ubiquity of carbon, the assumption of its amazing properties not so long ago led to the development of the use of carbon materials as additives in grouting mixtures for cementing wells. The analysis of scientific articles shows that today methods and ways are being studied for the introduction of graphite and graphene nanoplates, as well as carbon nanotubes into grouting Portland cement to improve their characteristics. Let’s consider the features of each carbon modification, as well as the effect of new materials on the properties of the improved cement composition.
