Iron Nanoparticle Modified Smart Cement for Real Time Monitoring of Ultra Deepwater Oil Well Cementing Applications

摘要

Better controls during well drilling and cementing operation are critical to ensure safety during constructionrnand the entire service life of the wells. For a successful cementing operation determine the setting ofrncement in place length of cement supporting the casing and performance of the cement after hardening.rnAt present there are no technologies available to monitor the cementing operations without using buriedrnsensors that could weaken the cement sheath.rnIn this study, smart cement with 0.38 water-to-cement ratio was modified with Iron nanoparticlesrn(NanoFe) to have better sensing properties, so that its behavior can be monitored at various stages ofrnconstruction and during the service life of wells. A series of experiments evaluated the smart cementrnbehavior with and without NanoFe in order to identify the most reliable sensing properties that can alsornbe relatively easily monitored. Tests were performed on the smart cement from the time of mixing tornhardened state behavior. During the initial setting the electrical resistivity changed with time based on thernamount of NanoFe used to modify smart oil well cement. A new quantification concept has beenrndeveloped to characterize cement curing based on electrical resistivity changes in the first 24 hours ofrncuring. When cement was modified with 0.1 percent of conductive filer (CF), the piezoresistive behaviorrnof the hardened smart cement was substantially improved without affecting the rheological and settingrnproperties of the cement. For the smart cement the resistivity change at peak stress was about 2000 timesrnhigher than the change in the compressive strain after 28 days of curing.rnThe shear thinning behavior of the smart cement slurries with and without NanoFe at two differentrntemperatures (25℃ and 85℃) have been quantified using the new hyperbolic model and compared withrnanother constitutive model with three material parameters, Vocadlo model. The results showed that thernhyperbolic model predicated the shear thinning relationship between the shear stress and shear strain raternof the NanoFe modified smart cement slurries very well. Also the hyperbolic model has a maximum shearrnstress limit were as the other model did not have a limit on the maximum shear stress. Based on thernhyperbolic model the maximum shear stresses produced by the 0 percent, 0.5 percent, and 1 percent ofrnNanoFe at temperature of 25℃ were 175 Pa, 224 Pa, and 298 Pa, respectively. The maximum shearrnstresses produced by the 0 percent, 0.5 percent, and 1 percent of NanoFe at temperature of 85℃ were 349rnPa, 377 Pa and 465 Pa respectively. Additional of 1 percent NanoFe reduced the initial resistivity of thernsmart cement by 16 percent. In a 24-hour period the maximum change in the electrical resistivity (RI_(24hr))rnfor the smart cement without NanoFe was 333 percent. The RI_(24hr) for the smart cement with NanoFernincreased with the amount of NanoFe. Addition of 1 percent NanoFe increased the compressive strengthrnof the smart cement by 26 percent and 42 percent after 1 day and 28 days of curing respectively. The testrnresults showed that NanoFe decreased the electrical resistivity of the smart cement slurries with andrnwithout NanoFe. For the smart cement modified with NanoFe, the resistivity change at peak stress wasrnover 2800 times higher than the change in the compressive strain. A linear correlation was obtainedrnbetween the RI_(24hr) and the compressive strength of the modified smart cement based on the curing time.