International Journal of Science and Engineering Applications Volume 5 Issue 1, 2016, ISSN-2319-7560 (Online) www.ijsea.com 7 Effect of AL 2 O 3 Nanoparticles on the Rheological Properties of Water Based Mud Amarfio, Eric Mensah Department of Petroleum Engineering African University of Science and Technology Abuja, Nigeria Abdulkadir, Mukhtah Department of Petroleum Engineering African University of Science and Technology Abuja, Nigeria Abstract: This research work investigates into the performance of Aluminium Oxide nanoparticles in water based bentonite drilling fluid at high temperature formations. We looked into the thermal stability effect of the Aluminium oxide nanoparticles on the drilling fluid at varying temperature conditions. We analyzed the interactive effects of temperature, the Aluminium Oxide nanoparticles and shear rates on the shear stress of the drilling fluid. Optimization of these parameters at the high and low point of the shear stress of the drilling fluid was analyzed. We also developed a predictive expression for Shear stress as a response variable for changes in temperature, Aluminium Oxide nanoparticle and shear rate. Keywords: Thermal stability, Optimization, nanoparticles, bentonite drilling fluid, interactive effect, shear stress 1. INTRODUCTION Drilling fluid plays very vital role in the drilling operations of oil and gas industries. It plays a multifunctional role such as removal of cuttings, lubrication of bits, maintenance of wellbore stability and prevention of inflow and outflow of fluids between borehole and the formation. The use of water- based muds (WBMs), oil based muds (OBMs) and other synthetic based muds (SBMs) in drilling of oil and gas wells has increased considerably over the past years. New mud systems are continuously being developed and existing systems are being refined to reduce exploration costs. Now the advancement of drilling operations into high temperature formations demand the usage of drilling fluid formulae that will withstand high temperatures by stabilizing the integrity of the rheology of the drilling fluid under such conditions [9, 11] . At high temperature conditions, better thermally stable drilling fluid is required to maintain the rheological properties of this multifunctional fluid [2, 4]. Equipping drilling fluid to perform its basic functions under such conditions requires engineering the fluid with additives. Developing a stable fluid to maintain the rheological properties is an important issue at this stage [5, 8]. This study therefore explored the use of Alpha Aluminium Oxide nanoparticles as stabilizing agent under the conditions of high temperatures. Many other studies and operation on the field have employed different types of chemicals and polymers in designing the drilling mud to meet some functional requirements such as the appropriate mud rheology, density, mud activity, fluid loss control property. Studies of nanoparticles have shown their unique abilities in their functionalities such as thermal conductivity, electrical conductivity, optical features etc. [1, 3, 6,10]. Our aim and objectives for this work are; to evaluate the effect of temperature on the drilling fluid at varying mass fractions of the Aluminium Oxide nanoparticles and different shear rates; also to evaluate the interactive effect of temperature, Aluminium Oxide nanoparticle and the Shear rate on the Shear stress of the drilling fluid; and finally to develop a prediction model that predict the effect of the nanoparticles at higher temperature formations. 2. EXPERIMENTAL PROCEDURE 2.1 Chemical Synthesis of Iron Oxide Nanoparticles Aluminium oxide nanoparticles used was obtained from stock with the following characteristic: Spherical morphology and particle size of 40nm and crystal size of 150nm 2.2 Procedure for Bentonite Drilling Fluid Formulation 350 ml of fresh water was measured using a measuring cylinder and was added to 22.5 g of bentonite and stirred in the bucket until no more lumps were observable by the help of an electric mixer. The drilling fluid was left to stay overnight (16 hours) to swell. The formulated bentonite mud was divided to four different samples. Aluminium Oxide Nanoparticles were then added to the formulated bentonite mud samples each in the following mass fractions 0.5 g, 1 g, and 1.5 g. The sample fluids are then stirred vigorously and homogenized with an electronic mixer for about 2 minutes to ensure stable and uniform dispersion of nanoparticles in the fluid for the study. The bentonite fluid and the treated bentonite fluids were used for the various experiments. 3. EXPERIMENTAL RESULTS AND DISCUSSION The viscometer analysis was completed for the aluminium oxide Np enriched drilling fluid. Analysis and discussion mainly centers on the effect on the fluid model and the thermal stability of the drilling fluids as they undergo temperature variation. Also, the statistical analysis of the parameters that affect the rheology of the drilling fluid.