Adsorption and desorption behavior of nanoparticles on rock surfaces
JIANG Ajiao, SONG Zhaojie, Cheng Tingting, HOU Jirui, ZHAI Haoya, SHANG Dansen, LI Yuzhen, ZHAO Chuang
1 Unconventional Petroleum Research Institute, China University of Petroleum-Beijing, Beijing 102249, China 2 Basic Theory Laboratory of Enhanced Oil Recovery in Low Permeability Oilfields, Key Laboratory of Tertiary Oil Recovery, CNPC, Beijing 102249, China 3 Beijing Key Laboratory of Greenhouse Gas Sequestration and Oil Exploitation, Beijing 102249, China
Low permeability reservoirs play a major part in China’s oil and gas exploitation. They feature small pore throats,poor connectivity and strong capillary effects, while nanoparticles have been applied to enhance oil recovery due to their small size. However, nanoparticles present strong adsorption ability in porous media, so it is imperative to examine the adsorption and desorption behavior of nanoparticles to improve their applications in oilfields. In order to study the adsorption and desorption behavior of nanoparticles on rock surfaces, the static adsorption loss of hydrophilic and hydrophobic nanoparticles on quartz sand and outcrop sand surfaces was quantified using the sealed oscillation equilibrium method. Experimental results showed that hydrophilic and hydrophobic nanoparticles were mainly physically adsorbed on the rock surface and exhibited characteristics of single-layer adsorption. Their isothermal adsorption curves had the characteristics of an "S" isothermal adsorption curve and could achieve good agreement with the Freundlich isothermal adsorption model. Hydrophilic nanoparticles had relatively poor adsorption capacity and the final adsorption loss after desorption was smaller, while hydrophobic nanoparticles presented the opposite adsorption and desorption behavior. This experimental study can provide theoretical guidance for a better understanding of nanofluid technology and its application in oilfields.
