Acidic attack of cement based materials under the common action of high, ambient temperature and pressure

The cement materials in geothermal bore holes used to be exposed to the acidic attack under the common action of ambient high, temperatures and pressure. As it is known the waters in the deep geothermal wells are usually very aggressive to the applied cementing materials. Acidic aggressivity used to be a dominating type. Therefore, in the interest of the ensuring of life service of the cementing material it should be high acidic resistant. But it is a crucial problem due to the fact that practically all-protective measurements like e.g. the choice of the cement, increased density of material and others are weak and insufficient. One presumption of the ensuring of acidic resistance of cementing material is the correct evaluation of cooperating factors conditioning its acidic resistance and the factors of the aggressivity of environment. Both are of complex character depending on several conditioning factors. This complexness, as a rule, is not taken into consideration. However, such an evaluation current in the practice is entirely unsatisfied and incorrect. Therefore, further factors should be taken into consideration. These are the subject of the presented paper showing also the complexness of the point at issue.

► Acidic geothermal waters and alkalic cementing material are conditions for acidic deterioration. ► Water aggressivity factors are species present, concentration, temperature and pressure in well. ► Cementing material resistance factors are cement, w/c ratio, processing and curing regime used. ► All factors make should be considered at the design of the composition of the cementing mixtures. ► Exacting character is increased by the necessity of use negative high w/c ratios for properties.