Evaluation of Guinea Corn Husk Ash As Oil-Well Cement Slurry Extender

The objective of primary cementing operation is to provide zonal isolation while drilling oil and gas wells. To achieve this purpose, cement slurries are designed by adding additives to control certain properties such as density, free fluid, compressive strength, rheology, among others. These additives are imported whereas Ghana produces large amount of agro-waste yearly causing environmental nuisance, though these have the potentials of being used in the petroleum industry. The extender, a light weight additive is one of such materials used to reduce the hydrostatic pressure of the fluid column during cement placement. This research evaluates the effect of an agro-waste, guinea corn husk ash as an extender on the properties of class G cement slurries. Thus the density, free fluid, compressive strength and rheological properties of class G cement slurries were experimentally evaluated. Samples were designed using varied quantities of the ash levels by weight of cement. These were subjected to rheological, free fluid and density test and the compressive strength of cured samples at 60 oC and 80 oC were determined after 8 and 16 hours. The results showed that increasing concentrations of ash shows a corresponding increase in compressive strength. The optimum compressive strength is attained at ash concentrations of 3-5 %. The rheological properties confirm that the slurries have a good pumpability due to the low plastic viscosity values recorded. The decrease in free fluid content as concentration of ash was increased is indicative of the ability of the ash to ensure stability of the slurry during cementing operations. The guinea corn husk ash, a product developed from agro-waste showed properties of an oil well cement extender and thus can be used as cement additive. Utilising such additives developed locally in the petroleum industry would enhance local content and reduce environmental pollution in Ghana.