Improving Cement Sheet Contraction and Strength Retrogression for High Temperature Well Cementing Using Local Material

Cement sheet contraction and strength retrogression associated with high temperature well cementing has been prevented in the industry over the years with the use of silica flour. Due to the difficulty in sourcing the silica flour, Tympanotonus fuscatus commonly known as "Periwinkle shell" was investigated as an alternative. Elemental and Oxides characterization were carried out and periwinkle shell powder contains CaO – 69.54%, SiO2 – 16.96%, Al2O3 – 12.06%. API standard procedures were employed throughout the laboratory measurements to determine compressive strength using periwinkle shells powder at 35% and 40% (BWOC), compressive strength values at 24hrs/30days gave 4350/4365psi and 4485/4498psi at 200°F. But at 35% and 40% (BWOC), compressive strength values at 24hrs/30days gave 4811/4895psi and 4904/4927psi at 250°F. Using Silica flour as a control additive in the cement slurry formulations at 35% and 40% (BWOC) gave compressive strength values at 24hrs/30days of 3629/3652psi and 3699/3716psi at 200°F, at 35% and 40% (BWOC) gave compressive strength of 3720/3729psi and 3728/3753psi at 250°F. This showed that at equal concentrations and conditions, periwinkle shell powder gave the better result than the conventional silica flour. Also, the waste periwinkle shell possesses no commercial value and being locally available, it's usage in cement slurry for cement sheet contraction and strength retrogression reduces cost of HPHT cement operations.