Non⁃ionic surfactants, fluorinated cationic surfactants, and fluorocarbon polymers have been evaluated for their ability to alter wettability and injectivity in tight sandstone reservoirs through contact angle tests and injectability tests. The results showed that, compared with other chemical agents, the fluorocarbon polymer CRS⁃850 had better gas wetting inversion effect, and the contact angle of the core surface increases from 45.6° to 92.1°; the self⁃absorption of salt water before wettability changing was 0.360 8 g, the self⁃absorption after treatment dropped to 0.020 6 g, the core self⁃aspiration decreased by 98.85%, and the max self⁃suction rate decreased from 0.053 g/min to 0.002 g/min. The wet reversal agent increased the liquid⁃phase percolation capacity of the coreand the gas⁃driving permeation rate significantly, and the recovery effect of core gas drive permeability is remarkable, which increases by 501.69% to 673.91% on the basis of the gas flooding brine, indicating that the gas⁃wetting reverser has beneficial to remove liquid⁃phase damage in tight sandstone reservoirs.

The Bozi block of the Tarim Oilfield is a typical tight sand condensate gas reservoir with serious wax plugging. So it is necessary to study the phase behavior and the wax deposition pattern of well fluids in Bozi gas reservoir, which will provide the phase enveloping diagram of the condensate gas and then help to control the paraffin deposition. In this study, the PVT tester and the self⁃designed microscopic solid deposition tester with visualized windows are used to get the phase enveloping line of the condensate gas of Well Bozi 104. The condensate oil and wax precipitation are analyzed based on the results of software simulation and production data. The results show that in the process of condensate gas changing with temperature and pressure, different phase states are produced, such as gas phase region, gas⁃liquid two phase region, gas⁃solid two phase region and gas⁃liquid⁃solid three phase region. The experimental results are used to correct the software simulation results to obtain different temperature and pressure phase. The state envelope is used to predict the conditions for liquid and wax precipitation when the production wells are in different production stages; the condensate and wax deposition areas of the Bozi 104 wells are located on the ground transmission pipelines, and appropriate anti⁃wax measures should be made