Application of Corrosion Resistant Latex Cement Slurry in Yuanba Area

In Yuanba Area where high-pressure gas zones are commonly encountered in exploratory wells,and hydrogen sulfide (H2S) is contained in the natural gas,it is of crucial importance to employ latex cement slurry that can prevent gas channeling and corrosion to increase life span of wells.In view of the formation characteristics of Yuanba Area and combined with the application experience of latex cement slurry in other regions,the fundamental formula of latex cement slurry was worked out.Lab experiments prove that all the sensitive factors,such as shear rate,water quality and density had little effect on the properties of latex cement slurry,which is suitable for the sophisticated circumstances in Yuanba Area.Although the thickening time shortens with the rise in temperature,it fulfills the requirements of cementing operation in Yuanba Area.The corrosion resistivity of the latex cement slurry was evaluated by observing the structure changes of cement stones under scanning electron microscope (SEM) before and after corrosion,and comparing the strength and permeablity measured before and after corrosion by H2S,and the tested rates of corrosion,and the corrosion resistant mechanism of latex cement slurry was investigated as well.The cement stone formed by latex cement slurry exhibited preferable corrosion resistant performance to H2S.In the environment with a 4.0% volume fraction of H2S,its rate of corrosion was less than 16%,which was much lower than that of the cement stone formed by conventional cement slurry.Field application results indicated that utilization of corrosion resistant latex cement slurry in Yuanba Area could improve cementing quality and prevent the corrosion of H2S on cementing quality.