Measurements Of Surface Wettability And Adhesion And Its Use In Oilfield Surface Chemistry

Understanding a surface wettability and adhesion property is very important in a variety of areas, e.g. in enhancing oil recovery, hydrophilicity/hydrophobicity, self-cleaning, microfluidic devices and protein-substrate interaction etc. This dissertation studied surface wettging behavior and adhesion on the wettability gradient surfaces by utilizing a method for direct force measurement of droplets on surfaces with a microbalance and adhesion force measurement with atomic force microscopy, and we probed into the relationship between the two methods. This work contributes to disclose the law of absorption behavior of crude oil and surfactant and the absorption style to guide optimization of oil-displacing agents, enhanced oil recovery. The main results of this thesis are as follows:1. Model surfaces with controllable wettability gradient are made by adjusting the feed mole ratio of 11-mercapto-1-undecanol and 1-octadecanethiol to form mixed self-assembled monolayers on gold. The surface adhesion spectra were obtained by force volume analysis at nanometer scale with atomic force microscopy and direct force measurement of droplets on surfaces with a microbalance. The results from direct measurement of liquid droplet-substrate adhesion are in good agreement with the measurements of force volume statistics and contact angle measurement. It can thus be a useful supplement approach to understand surface wetting and adhesion property. The absorption behavior of sodium dodecyl benzene sulfonate (SDBS) on the wettability gradient surfaces was investigated. Absorptive capacity of SDBS is increased along with surface hydrophobicity increase, so absorption loss of SDBS is mainly occurred on the hydrophobic surfaces. And crude oil is also apt to absorb on the hydrophobic surface.2. A novel compound of imidazolium type of ionic liquid (IL) containing a functional group of biomimetic catecholic anchor was synthesized. The catecholic IL was then successfully immobilized on silicon surface by the assembly of the biofuncitonal anchor. Wettability, adhesion and friction force for the catecholic IL SAMs were modulated by"direct"exchanging of the counteranions, which follow the trend of Clï¹¥BF4ï¹¥NTf2. ILs composite films were prepared by spin-coating of the L-B106 IL thin films onto catecholic IL SAMs. The presence of IL SAMs on surface can improve the wettability of the IL films and so the film quality and mechanical properties.3. The absorption behavior of sodium dodecyl benzene sulfonate (SDBS) and cetyltrimethyl ammonium bromide (CTAB) on mica surfaces, which is a common silicate mineral, were investigated by AFM. And the wetting and adhesion behavior of water droplets on the surfaces were investigated, and the results have a good correlation with AFM measurement. SDBS is more likely to be absorbed on mica surface than CTAB under the same conditions.Bitumen film was fabricated by spin-coating of toluene solution of bitumen on silicon surface. Desorption behavior of bitumen film in surfactants solution (SDBS and CTAB) under different concentration were studied by the means of AFM, wetting and adhesion spectra measurement with a water droplet probe. Through the desorption process of bitumen we can see that SDBS solution had the better washing effects at the concentration of CMC. Desorption behavior of bitumen in high temperature and high salinity environment was also investigated by using the same methods. Surface Wettability of the bitumen films were altered when they were exposed in high temperature and high salinity solution.