Design of plasticized cement slurry system with high strength and low density and its application

The conventional cement slurry system with low density has the shortage of low strength while cementing the region with low pressure and easily lost circulation.So it needs to be improved to fulfill the higher requirement of oil/gas exploration and development.A four-level particles filled structure,mainly made up of microspheres,cement particles,micro-silicon particles,intensifiers for particle gradation,and a systematic plasticized slurry system with high strength and low density consisting of composite toughing fibers are developed.A laboratory experiment is conducted to test the cement strength,the anti-impact of cement loops,the performance of cement slurry,and the stability of slurry.Results show that cement slurry has the advantages of good rheological property,less loss of water,and short transition time.It can greatly improve the composite strength of cement rocks,the stability and anti-channeling property of cement slurry.What’s more,it is compatible with other additives.The cement slurry has been applied in Shengli Oilfield and northeastern Sichuan,and good results have been attained.This is a feasible approach to solve the problems of cementing the wells with low pressure and easily lost circulation.