Strength properties and microstructure of Portland slag cement for well casings under the influence of high temperatures

Abstract

Thermobaric conditions in oil and gas wells require the use of backfill materials with special physical and chemical properties. Cement composites are subject to the requirements of fluidity (to ensure uninterrupted delivery to the cementing site), timely formation of the necessary mechanical strength (to prevent the interaction between the cement glass and reservoir fluids), corrosion resistance, impermeability and durability. Therefore, the composition of the cement slurry should be selected based on the mining and geological characteristics of the well.Wellbores wall are reinforced with protective pipes, which are attached to the well with cement or cement slurry. It is needed to protect wellbores wall from rock falls, gas, oil and water shows and to isolate productive formations. If this operation is carried out qualitatively, then the outer part of the casing string will be protected from the impact of the formation fluid. Otherwise, pipe corrosion may occur, which can lead to the destruction of the cement stone and, as a result, to accidents.