Compressive Strength Changing Law of Oil Well Cement Paste under Corporate Corrosion of HCO₃^- and SO₄^2-

Abstract

On the basis of analyzing the oil well cement corrosion mechanism by SO42- and HCO3-, the corrosion products, microstructure and compressive strength of cement stone were measured and the changing regularity and influence factors of compressive strength were analyzed under different experimental conditions. The following conclusions can be drawn. Under the interactive corrosion effect of SO42- and HCO3-, Ca(OH)2 in cement stone was dissolved out and consumed, the calcium silicate hydrate was decomposed, ettringite, gypsum, calcite and thaumasite were produced which destroyed the structure and components of cement stone primary products and led the compressive strength of corrosion cement stone decline. With the increases of ion concentration of corrosive solution, temperature and corrosive time, the compressive strength was decreased gradually, even collapsed completely.

Mechanical Properties and Microscopic Mechanism of Coral Sand‐Cement Mortar

“…Especially during the first 7 days, the volume expansion of both mortar samples was very obvious. In addition, the volume change of coral mortar was more obvious at this stage due to the additional hydration reaction of Mg 2+ and SO 4 2− introduced from coral sand [24,25]. e second stage was the volume shrinkage period of mortar during 11∼59 days.…”