Research On Oil Vapor Water Permeation Adsorption Process Based On OIRD Technology

New technologies for material characterization,testing and analysis are expected to solve many new scientific and engineering problems in oil and gas exploration.New technologies for material characterization,testing and analysis are expected to solve many new scientific and engineering problems in oil and gas exploration.Oil and gas resources exist in the interior of the rock and continue to undergo osmotic adsorption in the long-term evolution and production process.The research on the osmotic adsorption process and mechanism has an important impact on the enhanced oil recovery.Generally speaking,there are charges on the surface of mineral rocks.Under the action of hydrogen bonds,electrostatic force and intermolecular force,the mineral surface and the inner wall of the pore and slit structure will adsorb water molecules to form a water film of a certain thickness.The thickness and stability characteristics of water film in the nanopores are the focus and difficulty in evaluating reservoirs.Although existing analytical techniques（such as electron microscopy）are highly effective in high-resolution imaging,for osmotic adsorption,real-time monitoring of dynamic processes and the formation of oil-gas-water films（often with nanoscale longitudinal thickness）There are still many difficulties in the longitudinal analysis of,and new characterization and test analysis techniques are urgently needed.The oblique incident reflectance difference（OIRD）technology is a new material testing and analysis technology that is very sensitive to the changes of materials’surface/interface,because of its label-free,real-time,high-throughput and non-destructive testing and longitudinal resolution that can reach nanometer level,it has a wide range of application prospects in the fields of biomedicine,thin film material detection and oil and gas.At present,the application of this technology in the dynamic osmotic adsorption of oil,gas and water still needs further in-depth research.In this paper,the oblique incident reflectance difference technique is used to monitor the water vapor adsorption process of sandstone slices and mica monoliths,and the relationship between adsorption rate and humidity and other factors is studied,and the influence of ion concentration and other factors on the permeation rate is expounded.The main research results are as follows:（1）According to the OIRD imaginary signal imaging images of sandstone slices and monolayer mica slices during the adsorption of water vapor,it can be seen that there are special adsorption sites on the surfaces of the two samples.These special adsorption sites are generally pores and seams or regions that are prone to hydrogen bonding,such as Si O₂.From the difference map in adjacent time intervals,it can be seen that adsorption generally starts from the defect position on the surface of the sample,and migrates to other positions under the driving of surface tension.According to the imaging diagram of the adsorption process of substances with different surface hydrophilicity,it is inferred that the stronger the hydrophilicity of the substance,the faster the adsorption process.（2）The OIRD signal value increased gradually with the increase of adsorption time,and then tended to be stable.It can be seen that during the adsorption process,the pore-fracture structure will absorb water molecules to form a hydration film on the rock surface due to the trend of reducing the surface free energy,and the hydration film formed subsequently adsorbs water molecules through hydrogen bonds,so that the thickness gradually increases,until the late adsorption stage,the thickness of the hydration film tends to be stable.（3）When the liquid passes through the pores and throats on the rock surface,cations such as Na⁺in the aqueous solution form hydrated cations formed by electrostatic interaction with water molecules,which are adsorbed to the surface of the particles,forming a hydration layer with a larger thickness but a weaker structure,which greatly reduces the Increasing the thickness of the hydration film greatly reduces the resistance of water molecules when they pass through the throat,effectively accelerates the movement speed of water molecules in the pores and throats,and improves the permeation rate of water molecules.