Evaluation and Beneficiation of Bentonitic Clays from Pindiga Formation in Benue Trough

Problem statement: This study aimed at evaluating and beneficiating Bentonitic clays of Pindiga Formation from the upper Benue trough in northeastern Nigeria to meet the standard required for use in oil well drilling. This will reduce the dependence on imported Bentonite into the country, increase foreign exchange, improve the country's economy and create employment opportunities. Approach: Three clay samples from different locations within Pindiga Formation were collected using standard sampling procedure and brought to the laboratory for the study. Evaluation of Loss On Ignition (LOI) was carried out using "Labocon" Furnace (model 2-1200), elemental composition of the samples were determined using Instrumental Neutron Activation Analysis (INAA) and X-Ray Fluorescence (XRF) while mineralogical phases of the samples were determined by X-Ray Diffractometry. Results: Results of analysis of crude Bentonitic clays indicates that the clays are Ca-based which require some level of beneficiation before they can attain the properties that will qualify its use in oil well drilling, while other properties such as Aluminum-Silicon ration which ranges between 0.34-0.39 as against 0.38 for the standard Wyoming Bentonite, LOI ranges between 14.8-15.63 as against 15.73 for the standard and fineness of the samples all attained the required standard even before beneficiation. After beneficiating the samples, their rheological and other physical properties was found to have improved to a level that is acceptable for use in oil well drilling except for yield points which was still lower. Maximum values recorded for viscosity and yield points for crude and beneficiated samples at 300 and 600 rpm are 5, 34.5 and 3, 9 while 15 was recorded for floating drill cuttings, respectively. API has specified the viscosity and yield to be greater than or equal to 30 for viscosity at 600 rpm and yield point at less than or equal to 3. Conclusion: This result indicates that Bentonitic clays from Pindiga Formation in Benue trough, northeastern Nigeria are Ca-base but can be beneficiated using sodium carbonate as beneficiating agent and ion exchange procedure.