A Comparative Analysis of Commercial Bentonite and Local Clay as Viscosifier in Water-Based Mud: A Case Study of Ire-Ekiti Clay

Abstract The search for an alternative to commercial bentonite as a drilling fluid has become imperative in Nigeria's oil and gas sector. The local clay came from Ekiti State, Nigeria's Ire-Ekiti. The clay's properties were ascertained and contrasted with those of bentonite, the preferred clay for drilling operations, in order to manufacture water-based mud. The obtained results indicate a considerable difference in the pH values and rheological properties of the prepared drilling fluid in comparison to bentonite. This is because clay and water are attracted to it, and its inclination to swell is inhibited by the low concentration of sodium cations (Na++). The local mud's pH increased by 15.2% from 8.11 to 11.02 and by 8% from 10.00 to 11.73 when it was beneficiated with soda ash (Na2CO3) at a concentration of 5.0 g clay at 63 microns sieve size to 350 ml of the mud. When PAC-HV was added to the mixture, the marsh funnel viscosity increased by 4.4% and 7.6%, apparent viscosity at 63 microns sieve size decreased by 26.6%, and at 150 microns sieve size increased drastically by 55.8%, but water loss decreased drastically by 32.8% and 66.8%. At both sieve sizes, the clay density increased by 1.2% from 8.50 lb/gal to 8.70 lb/gal after adding 10 g of barite (BaSO4) to 350 ml of the mixture. Thus, when beneficiated with soda ash (Na2CO3), the Ire clay shows good rheological properties at significant concentration that would compare favourably with those of bentonite; nevertheless, PAC-HV needs to be increased above 1.0 g at 150 microns sieve size. Thus, it is possible to create a drilling fluid using Ire clay.