Abstract: Four (4) samples A, B, C and D were developed using bentonite clay, rice husk, and xanthan gum in different proportions based on their rheological properties and thixotropic property (Gel strength), pH and density values. Additives (NaOH, NaCl, Na2CO3 and BaSO4) were added to the four samples in composition of 1%, 2%, 3% for (NaOH, NaCl, Na2CO3) and 5%, 10%, 15% for (BaSO4) at temperature of 30 oC. FANN 35 viscometer was used to measure their rheological properties and thixotropic property (Gel strength), while pH meter and mud balance were use to measure their pH and density values respectively. The maximum pH, apparent viscosity (AV) and Gel strength in 10 seconds (GS   10 (sec)) corresponds to 9.1, 51.3 cP and 34.2 (lbf/100 ft2) respectively were observed in sample A without chemical additive. From the results obtained the chemical additives had positive impacts on the rheological properties of the drilling fluid samples. Sample A with xanthan gum and bentonite only had most improved viscosity when the chemical additives were added followed by sample B with bentonite (24.5g), rice husk (20g) and xanthan gum (1g). The Gel strength of the samples were increased by the addition of any of the chemical additives, samples A and B still had more improvement than the other two samples. The yield point and plastic viscosity (YP/PV ratio values) results revealed that the carrying capacity of the drilling fluid samples could be increased by the addition of NaOH, NaCl and BaSO4. The pH values of all the samples were alkaline close to neutral with addition of the chemical additives. Thus, it could be concluded that drilling fluid with 20g rice husk and 1 g xanthan gum and standard 24.5g bentonite proportion could be improved upon with the addition of any of the chemical additives tested in appropriate quantity for effective performance in drilling operations.

Keywords: Rice husk, chemical additives, rheological properties, drilling fluid.

| DOI: 10.17148/IARJSET.2023.10301