ADSORPTION BEHAVIOR AND MODIFICATION OF MODIFIED NANO-SILICA NANO-MICROSPHERE FLUID ON QUARTZ SURFACE FOR IMPROVING CONDENSATE GAS RESERVOIR PRODUCTIVITY

摘要

Due to production methods,the pressure in the near-well zone is usually lower than the dew point pressure of the gas phase,and the anti-condensation occurs in the near-well zone,which causes liquid to block the pores,resulting in a decline in oil and gas seepage capacity,which severely restricts condensate gas reservoir capacity.Wetting modification is a common method to reduce the retention of liquid phase near the well.This paper evaluates the effect of a self-made modified nano-silica nano-microsphere fluid wetting modification,and studies its adsorption behavior.The results show that the concentration of nano-microspheres significantly changes the contact angle of the sandstone surface.As the concentration increases,the contact angle increases rapidly.When the concentration is 0.5%,the contact angle reaches the maximum value,the contact angle in the water phase is 123.19°,and the contact angle in the oil phase is 106.56°.At different concentrations,the growth trend of each adsorption curve is similar.In the early stage of adsorption,the adsorption amount increases rapidly with time,then the growth trend gradually slows down,and finally reaches equilibrium.The fitting result of the pseudosecond-order kinetic model is closer to the experimental value.The equilibrium adsorption results show that,as the concentration of nano-microspheres increases,the equilibrium adsorption amount first increases rapidly.When the concentration reaches a certain level,the equilibrium adsorption amount tends to be stable.This process can be accurately fitted by the Langmuir model.After the sandstone core was treated with nano-microsphere fluid,the self-absorption volume decreased significantly,which was about half of the self-absorption volume before treatment.The calculation results of the adhesion force also proved this point.When the nano-microsphere fluid concentration reached 1.5%,the adhesion force decreased from the initial 138.0133 mN/m to 17.0503 mN/m.It shows that after the core is treated with nano-microsphere fluid,a hydrophobic layer is formed on the surface of the core through adsorption,which improves the core's wettability and greatly reduces the adhesion of solid to liquid,thereby reducing the binding of solid to water and the fluid,which is more favorable for the flow back.