IPA13-SE-001 PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION Thirty-Seventh Annual Convention & Exhibition, May 2013 SIMULATION OF POLYMER XANTHAN GUM FLOW THROUGH SYNTHETIC FRACTURE USING LATTICE BOLTZMANN METHOD Muhamammad Aufaristama* Irwan Ary Dharmawan* Adnan Nullah Hakim* Aditya Lesmana* Fella Tiffanny* ABSTRACT When a reservoir reaches production stage, level of oil production in the reservoir will decrease, leaving large residual oil left in the reservoir (residual oil saturation). It is important to find a way to increase oil recovery in order to pump the oil that remains in the reservoir. Polymer injection is one technique of enhanced oil recovery (EOR). Generally, oil is in the porous media, but on the condition of low porosity and permeability, oil is contained in the fractured media. It is important to understand how the fluid flows in a fractured media. Polymers is considered a non-Newtonian fluid, meaning the polymer has a viscosity that is not constant on Shear Stress [SK Baijal, 1982]. This study uses Lattice Boltzmann Methods D2Q9 for flow of single-phase polymer fluids simulation in 2-D fractured media, which shows shear thinning non-Newtonian behavior (n < 1). Power law and Carreau Yasuda viscosity models are proposed in this study to found relationship between effective viscosity and local shear rate. The study show shear stress arising from roughness and slit width of fractured media resulted changes in polymer viscosity. Keyword: EOR, Polymer flow, power law, Carreau-Yasuda, Lattice Boltzmann method INTRODUCTION In low porosity reservoirs, fluid will generally be staying at the reservoirs’ fractures[Koesoemadinata, 1988]. In some cases, the fluid will flow through a single fracture while in other cases the flow goes through fractures network. Thus, it is important to understand how the fluid flows in fractures. * University of Padjadjaran Once the oil production process takes place naturally, the longer the level of oil production in the reservoir will decrease, leaving quite large residual oil saturation in the reservoir. It is important to find a technique to obtain oil, which left in the reservoir [JJ Sheng, 2010]. One way to do it by process of enhanced oil recovery (EOR) using polymer injection. Polymer injection technique is used to improve water flooding by adding the polymer solution into the water so that the viscosity of water increases, thus lowering the water-oil mobility ratio of water-oil mobility ratio) [Lake, 1989]. Since water serves as a displacer, sweep efficiency will increase and pumps oil is left in the reservoir out, therefore oil recovery is enhanced. Polymers is considered a non- Newtonian fluid, which means that the polymer has a viscosity that is not constant with the shear stress [SK Baijal, 1982]. Fracture geometry cause changes in shear stress, which affects the level of roughness and the width of the fracture, resulting in polymer viscosity changes and speed. Type of polymer also affects the flow of the polymer in the fracture media. Characteristics of non-Newtonian fluid as it passes through the fractured media can be predicted by numerical modeling. Suitable viscosity models describing polymer flow model is Power Law and Carreau-Yasuda models. According to laboratory experiments by Bandulasena (2011) and Cannella (1988), both of these model of viscosity fit to the experiments. FRACTURED MEDIA Tectonic originated fractures can be described as parallel plate where width is smaller than length [Bates and Jackson, 1980]. Fracture is one of the secondary oil reservoirs [Koesoemadinata, 1988]. It