Research On The Effect Of Basic Zinc Carbonate On The H₂S Corrosion Resistance Of Oil Well Cement Stone

With the increasing development of explore of oil and gas,the number of three typically featured well,such as high temperature,high pressure,high H2S/CO2 containing,risen either.Originating from the nature gas,H2S erode and impair the cement sheath which resulted in gas channeling,pipeline corrosion and even well failure.All in all,enhancing the duration of the cement sheath in the acid atmosphere has a significant mean to manage a acid gas field.Both normal density(1.88g/cm3)and low density(1.4g/cm3)of cement sheath were studied in H2S corrosion within varied time period and ranged temperature.Then the strength,porosity and permeation of sample with corrosion were researched.XRD was used to analyze the microstructure of specimen and SEM was taken to observe the profile of that.Finally the mechanism of the corrosion caused by H2S was explored in detail.To obtain the way to improve the erosion resistance,the effect of basic zinc carbonate on the corrosive resistance of cement sheath was explored.Combine that effect and looking over the regulation of strength,porosity and permeation of sample with different basic zinc carbonate added,the finest additive volume of basic zinc carbonate was comfirmed.The main conclusions were following:(1)H2S corrosion impaired the strength of low density samples and the normal ones.Both of them had bigger porosity and deeper permeation.In addition,the erosive condition was more serious with the increase of corrosive time and temperature.(2)Ettringite,gypsum and SiO2 was founded in the cement at 30 ? and 60?.while SiO2and gypsum was discovered at 90?.However,Si02 was weak at bonding and gypsum had expansion in volume,which leaded to weakness of cement.(3)The effect of less additive volume of basic zinc carbonate in cement could be ignored in practical application.Basic zinc carbonate reacted with H2S rapidly and the product(ZnS)of that reaction inhabited the diffusion of H2S.That how basic zinc carbonate enhanced the corrosive resistance of cement.(4)As 1.5%basic zinc carbonate added into the cement,the normal density ones exhibited a fine erosive resistance.Beside,the effect of basic zinc carbonate on the strength of cements could be ignored compared with other additive volume.(5)The effect of basic zinc carbonate on the low density specimen was more significant than the normal ones even with same basic zinc carbonate added.Moreover,the corrosive resistance of low density cement with basic zinc carbonate was obviously less than that of normal ones.