Abstract

The experimental study was conducted on rheological properties in laboratory to measure the integrity of cement slurry. Three samples were used and analyzed at different parameters to check the elasticity of cement slurry. Additives with various concentrations, i.e. silica fume % BWOC (Present by Weight on Cement) (15, 17, 19 and 21), dispersant % Wt (Percent Weight) (0.21, 0.26 and 0.31) and additional 1; % Wt of fluid losscontrol were used to improve the performance of the cement slurry at the temperature of 123oC. The results have shown that increase in the concentration of dispersants that have caused to decrease in the Plastic Viscosity (PV), Yield Point (YP) and GS (Gel Strength). The rheological properties of cement were improved with the addition of fluid loss control additive in 21 % BWOC (Present by Weight on Cement) silica fume increase the water quantity in cement slurry that improve its durability and to reduce the strength retrogression in High Temperature High Pressure (HTHP) environment. Results were achieved through HTHP OFITE Viscometer (Model 1100).

Highlights

  • The oil well cementing is the process of slurry placement in the annulus space between casing and formation

  • Silica fume works as a water absorber, usually has a strong tendency to absorb the water in the cement slurry causing an increase in the gel of the slurry to make a strong network of cement and silica fume particles, which cause an increase in Plastic Viscosity (PV)

  • It was observed that using constant dispersant concentration at 0.21%Wt the GS of cement slurry was decreased from 8-5.5 lb/100 ft2 by increasing silica fume concentration

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Summary

INTRODUCTION

The oil well cementing is the process of slurry placement in the annulus space between casing and formation. Rheological study is very useful for petroleum industry to predict the cement slurry stability for zonal isolation, where cements slurry pumped down many feet to the earth for seal vertical limit of casing and formation, for that purpose cement must sustain in pump-able for several hours without any effects during placing at high temperature and pressure. The rheological properties of cement slurries are very important for simulating pump profile for optimum fluid displacement. The slurry properties can be change pressure and temperature with passage of flow regime with addition of multi additive system. This science of rheology is basically used to determine the relationships between shear stress and shear rate in steady laminar flow define Newtonian and non-Newtonian. Numbers of additives are used according to the condition of formation such as accelerators, retarders; extenders and weighting agents are used to increase the performance of cement slurry [2,17, 23, 24]

EXPERIMENTAL PROCEDURE
Electronic Balance
Electronic Standard 7000 Constant Speed Mixer
Plastic Viscosity of 13 PPG Cement Slurry
Yield Point of 13 PPG Cement Slurry
Combined Additive Effects on Plastic Viscosity of 13 ppg Slurry
CONCLUSIONS
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