Research On The Effects Of Slurry Properties And Borehole Condition On The Displacement Efficiency

In the course of cementing, improving the displacement efficiency incementingengineeringis abasicpremisetoprevent drillingfluidchanneling,guarantee the bonding strength of set cement and improve the sealingproperty of cement sheath. The displacement efficiency is affected by manyinteractedparameters, suchasthetechnologicmeasures,formationcondition,wellbore geometry, fluid mobility, cementing tools and so on. Due to thecomplexity of influencing factors, it is difficult to precisely simulate thedisplacement by means of laboratory experiments. It is, hence, of practicalimportance to systematical study the annular displacement mechanism bynumericalsimulation.Based on the large-scale CFD software FLUENT, the effects ofrheological parameters, eccentric annulus, special well condition and othervariables on the displacement efficiencywere studied bymeans of numericalsimulation.Thesimulationresults showthat increasingthedensitydifferencebetween the cement slurry and the drilling fluid, the consistency coefficientofcementslurryortheliquidityindex ofdrillingfluid,theplasticviscosityofcementslurry,andthe yieldpointofcementslurryordrillingfluid,allhelpto improve the displacement efficiency of cement slurry. On the contrary,increasing the liquidity index of cement slurry or the consistency coefficientof drilling fluid, or increasing the plastic viscosity of drilling fluid, willreduce the displacement efficiency of cement slurry. Meanwhile, when theeccentricity increases, the displacement efficiency decreases, and late-flowphenomenon becomes serious with the increase of eccentricity. For specialwell condition, if sufficient contact time is obtained, it is still hard to reachcomplete displacement. The lowest point of the displacement efficiency ofcement slurrylocates at the point which connects special well condition withnormal condition. Research results can contribute to better understand theannular displacement mechanism incement squeezing,and provide necessarytheoretical foundations for the design and execution of cementing.