UNPROCESSED OTA KAOLIN AS A WEIGHTING ADDITIVE IN DRILLING FLUID

Abstract—Drilling fluid cost and effectiveness are two key factors in drilling fluid selection. Kaolinitic clay is of the family of bentonite and investigation was carried out to check the effect of partial replacement of expensive bentonite in drilling mud with cheap Nigerian kaolin. Two types of kaolin, kaolin1 and kaolin2, were sources in deep wells at Ota, Ogun state, Nigeria at depths between 100ft and 120feet. The two types of kaolin were used naturally in unprocessed state. It was discovered that the apparent and actual viscosities of the mud reduces significantly with increasing kaolin1 and kaolin2 content. Replacement of bentonite with kaolin1 resulted in 85.7 % reduction in the mud viscosity while that of kaolin2 gave a corresponding 83.33 % reduction. This is an indication that bentonite is more effective than the two kaolin as a viscosifier. The density of the mud slurry increased significantly with more kaolin1 and kaolin2 addition with a 25 % and 27.25 % increase respectively at 100