2015 Volume 80 Issue 2 Pages 125-128
Recently, cellulose nanofiber (The width is 4-200 nm) that fined from wood pulp is in the spot light in various industries. Cellulose nanofiber (CNF) has a feature of high strength, high modulus, low coefficient of thermal expansion, and high transparency. Dai-ichi Kogyo Seiyaku Co., Ltd. is developing CNF as a new thickener, and we have already found the function such as the highly thixotropy, the emulsifying and suspending ability. In this study, we aimed at developing cellulose nanofiber as biodegradable and eco-friendly chemicals in oil and gas E&P industry.
The basic properties of CNF and other thickeners, such as guar gum, CMC, Xanthan gum, polyacrylamide were compared. And then, we found that CNF has highly thickening effect and yield value, and the degree of temperature dependence of the viscosity was found quite low. Also, we confirmed the ability of CNF to form a stable gel by being mixed with aluminium acetate basic as cross-linker and left standing for about 7hr.
The cross-linked gel did not collapse, and the weight loss was found very small when immersing in brine (8% NaCl & 2% CaCl2) solution. It is suggested that the gel works well as agent of water shut-off for oil/gas reservoirs. Apparent viscosity in case CNF flow the inside of porous media was measured by using visualized porous media model. As a result, CNF is thixotropic (the viscosity decrease with an increasing shear rate). Water flooding was carried out to high permeability model and low permeability model (connected in parallel) by using 3% NaCl solution as brine, and silicon oil. After that, polymer EOR was carried out by using 0.4% CNF. As a result, oil recovery rate was increase to 49% because of sweeping the low permeability model by CNF (Oil recovery rate of water flooding is 16%).
