Using in situ ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) measurements, the thermal behavior of octadecyltrichlorosilane (OTS) and 1H, 1H, 2H, and 2H-perfluorooctyltriethoxysilane (PTES) monolayers on SiO2 substrates has been investigated. OTS is thermally stable up to 573 K with vacuum annealing, whereas PTES starts decomposing at a moderate temperature between 373 K and 423 K. Vacuum annealing results in the decomposition of CF3 and CF2 species rather than desorption of the entire PTES molecule. In addition, our UPS results reveal that the work function (WF)of OTS remains the same after annealing; however WF of PTES decreases from ~5.62 eV to ~5.16 eV after annealing at 573 K.

An experimental method has been developed to determine the wettability, i.e., the contact angle, of a CO2-reservoir brine-reservoir rock system at high pressures and high temperature using the axisymmetric drop shape analysis (ADSA) technique for the sessile drop case. The laboratory experiments were conducted for dynamic contact angle of CO2-reservoir brine-reservoir rock covering three interesting salinities (0 mg/L, 14224.2 mg/L and 21460.6 mg/L) at P=6–35 MPa and T=97.5 °C. For pure water system, θad (static advancing contact angel) increases from 71.69° to 107.1° as pressure of CO2 increases from 6 MPa to 35 MPa. θad decreases from 71.48° to 42.01° for the 1# brine system and from 51.21° to 23.61° for the 2# brine system as pressure of CO2 increases from 6 MPa to 35 MPa. θad for 2# brine system (21460.6 mg/L) is lower than that for 1# brine system (14224.2 mg/L) under the each same pressure.