Research On The Performance Of Anti-corrosion Of Oil Well Cement

The cement sheath play an important role in sustaining casing, protecting bore hole stabilization, blocking the formation fluid to prevent cross flow between layers, which determines the life of oil well or casing life. The oil and natural gas contains acidic gas,such as H2S that exists in oil and gas layer or formation water, the acid gases will cause corrostion to the cement sheath under proper environmental conditions, which results in the decrease of cement sheath’s strength, permeability increase, In the most severe cases, the corrosion will cause different serious damage to the casing. As the corrosion increases, with the components of cement sheath destroyed, The cement sheath resist various stress completely lost in the downhole environment, and places a premium on fluid channeling and borehole wall sloughs accident in plastic formation, shortening the oil-gas well’s production lifetime and giving rise to tremendous economic losses. So, cement sheath’ proof-corresion competence to CO2and H2S increasely becomes the urgent-solving problem in the process of oil-gas field development.This paper investigates corrosion process of cement sheath and the influence factors in H2S and H2SO4acid medium environment, To deeply explore H2S corrosion process and features of cement sheath, Based on research work made by pioneers, This paper gives the new methods of anti-corrosion methods and anti-corrosion cement slurry of H2S corrosion and novel oil well cementing materials, At the same time, Form comparing the mechanical properties and microstructure of cement sheath corroded by H2S and H2SO4before and after to find the common characteristics, Using H2SO4corrosion instead of H2S corrosion to reduce experimental risk and economic cost when selecting anti-corrosion cement slurry of H2S corrosion.