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

In order to realize the efficient development of the oilfield,it is needed to evaluate the productivity of the reservoir. According to the structure of horizontal well, the form of fracture and the distance of fracture, combined with the theory of seepage mechanics, a well test analysis model for multistage fractured horizontal wells considering wellbore storage and skin factor is established. A typical curve fitting chart of pressure and derivative is obtained, and a well testing interpretation software system based on the theoretical plate is developed. Based on the well test interpretation software system compiled by the theoretical plate, the IPR curve and the production decline curve are plotted by using multistage fracturing horizontal well test interpretation software.The results show that under the same production conditions, the influence of fracture distance and crack skin factor on productivity is less than the effect of crack half length on productivity. According to the curve of production flow rate with bottomhole flow at different production stages and the curve of output with production time at different bottomhole flow pressures, and the production capacity is predicted and evaluated at different stages of fracturing horizontal wells. It provides a strong guarantee for the efficient development of multistage fracturing horizontal wells.

The enhanced oil recovery technology of ASG (alkali, surfactant and nitrogen) composite foam and water alternating injection was studied in high temperature and high salinity low permeability reservoir. The ASG foam and water alternating injection experiments were carried out through indoor flooding experiments, and compared with water flooding nitrogen flooding and surfactant flooding. The results show that the enhanced oil recovery of the method adopted by this study is 16.61%, 10.26% and 9.21%, respectively, compared with water flooding, nitrogen flooding and surfactant flooding technology. Experimental study on injection parameters optimization of ASG foam and water alternating injection is carried out, and the parameters such as slug size, injection rate and gas fluid ratio of ASG composite foam are optimized by bench scale displacement test. The results show that under the condition of the same foam injection volume (1.2 times the pore volume), the effect of foam slug injection with 0.4 times pore volume is best. The foam injection rate has an optimum value of 1.5 mL/min. When the injection rate is too low, less foam is produced, gasliquid separation is easy to occur, and the blocking effect is poor. When the injection rate is too high, the size of the bubble is different, and it is easy to cause the bubble to merge, causing the bubble to burst, and at the same time, it is easy to cause the shear defoaming of the foam. When the gas fluid ratio is 3∶1, 2∶1 and 1.5∶1, respectively, the recovery rate is 2.04% higher than that of the single gas fluid ratio.

 

Nanosilicon dioxide was organic modified with silane coupling agent KH550. The influence of modification conditions on surface ζpotential of nanosilicon dioxide was characterized by Zetasizer 3000. The modified nanosilicon dioxide was respectively compounded with petroleum sulfonate. The ability of the composite system for reducing the oil water interfacial tension was measured by interfacial tensiometer TX500. Turbiscan Lab was applied to analyze the stability of oilwater emulsion. The results showed that petroleum sulfonate system could reduce the oil water interfacial tension to about 2.30×10-2mN/m, and modified nanosilicon dioxide and petroleum sulfonate composite system could reduce that to about 5.42×10-3 mN/m, when the concentration of surfactant was 0.5% and the modified nanosilicon dioxide surface zeta potential was -50.1 mV. The oilwater interfacial tension change and mechanism of emulsion stability were analyzed through the changes of surface zeta potential of modified nanosilicon dioxide. 

Through measuring the basic physical properties and model Dv-111+programmable rheometer, the experimental research on rheological properties was done, which analysed the influence of water content ratio, temperature and shear rate. The results show that the rate of water content is a major factor that influences rheological characteristies of water-bearing super-heavy oil. With the change of water content ratio, the apparent viscosity of super heavy oil exhibits a more complex pattern. Oil water ratio greater than 30%, the non Newtonian character is not obvious when the rate of water content was over 30%. Whats more, the temperature and shear rate have an influence on the rheological property when the rate of water content was high. Different conditions have different flow pattern transition point. 