Cooperative Corrosion Action Law Of Oilwell Cement By SO₄^2- And HCO₃^-

This paper focus on the serious corrosion problems of oilwell cement corroded by the concentrated formation water of polymer flooding and ASP and the fluids rich in corrosive ions. The corrosion regulation and mechanism of oilwell cement by the cooperative action of HCO₃^- and SO₄^2- were researched on and analyzed which can enrich and improve the oilwell cement physicochemical theory, and provide foundation for the research and development of oilwell cement anti-corrosion technique.In the experiments, the main equipments were the high-temperature and high-pressure corrosion curing cauldron, X-ray diffractometer and scanning electron microscopy. Though analyzing the changes of compositions and microstructures and compressive strengthes of cement stone before and after corrosion, the corrosion regulation and mechanism by the cooperative action of HCO₃^- and SO₄^2- were researched on and revealed under different water quality fluctuation conditions, the affects of cooperative action of HCO₃^- and SO₄^2- on oilwell cement were comprehend. On the base of analyzing the data of formation water quality in different reservoir displacement mediums and the effects of cement slurry characteristic, three kinds of anti-HCO₃^- and SO₄^2- corrosion cement slurry were designed and developed .