Evaluating a Local Liquid Cement Retarder for Additional Use as a Dispersant for Cement Slurry in the Oil & Gas Industry

Abstract

- The increasing cost of oil & gas well cementing worldwide prompted this work to investigate the dispersion capability of a Local liquid cement retarder used in the Nigerian oil & gas industry to evaluate it for additional use as a dispersant in cement slurries. This work also aims to establish a procedure for evaluating this additional functionality of a cement retarder, as there is no standard procedure worldwide for such evaluation. Therefore, this work hinges on the effect of the liquid retarder on the rheology of cement slurry. Cement slurries were prepared with different amounts of the liquid retarder and conditioned to the test temperature in an Atmospheric Consistometer in accordance with API Spec 10B. The rheology of each cement slurry was measured using Chan-35 Rheometer. API Free water test was also conducted for each cement slurry in accordance with API Spec 10B. Results showed that the free water content of each cement slurry was less than the API limit of 3.5ml/250ml. Results revealed that the rheological parameters (Plastic viscosity and Yield stress) decreased with increasing amounts of the liquid retarder. This implies that the dispersion effect of the liquid retarder in a cement slurry can be leveraged to save cost by using only the retarder to achieve the required rheology and thickening time for a proposed cement job instead of using a conventional cement dispersant together with the liquid retarder to achieve the same job requirements especially when fluid loss control is adequate or not required.