Analysis of Nigerian Local Cement for Slurry Design in Oil and Gas Well Cementation

During oil and gas well cementation, fluid migration behind the cased holes is a major problem in drilling and completion both short terms and long terms after cementing operations. High formation pressures, high shrinkage rate of cement slurry, lack of mechanical seal and channeling due to poor cement slurry design leads to expensive drilling and completion operations and sometimes well abandonment. This research is a comparative analysis based on experimental study on the effectiveness of accelerators and retarders on local Nigerian cement using foreign cement as a control. The accelerators and the retarders were used for the cement slurry design to achieve better setting time, thickening time and compressive strength. The local Nigerian cement samples used were; the Eagle cement, Bua cement, Dangote cement and Ibeto cement while sample of class- G industrial foreign cement was used as a control standard. The cements were analysed to determine the percentage chemical composition (SiO2, CaO, Fe2O3, Al2O3, MgO, SO3,),the Particle size composition ,Compressive strength, Soundness of the cement and the consistency . The results obtained from the experiments showed that the Nigerian local cements in its original state have low setting time, low thickening time and very high fluid loss compared to class ?G foreign cement. Also, high gelation was observed on the local cement and therefore could not be considered effective on its natural state for slurry design in the oil and gas well cementation. However, further analysis showed that with the additions of some accelerators and retarders the local cement could compare favorably with the foreign cement and could be recommended for shallow oil well cementation.