Geochemical Evaluation of Geopressued Geothermal Wellbore Cement
نویسندگان
چکیده
Geopressured reservoirs can serve as ample source of geothermal energy with temperatures as high as 140 0C. Salinities are typically high in these reservoirs due to the dissolution of surrounding salt domes. Cement retrogression can occur under these geopressured geothermal conditions resulting from calcium silicate hydrate [3CaO2SiO23H2O] phase in hydrated cement converting to alpha dicalcium silicate hydrate [(Ca2(HSiO4)(OH)] phase due to the high temperature. The higher the temperature, the quicker the rate of transformation of calcium silicate hydrates [1]. This conversion changes the structure of the hydrated cement leading to increased porosity, permeability and lowered compressive strength [2]. The real problem lies in the great increase of permeability which makes the cement susceptible to corrosive formation fluids.
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