Study on Micro Production Mechanism of Corner Residual Oil after Polymer Flooding.

To study the microscopic production mechanism of corner residual oil after polymer flooding, microscopic visualization oil displacement technology and COMSOL finite element numerical simulation methods were used. The influence of the viscosity and interfacial tension of the oil displacement system after polymer flooding on the movement mechanism of the corner residual oil was studied. The results show that by increasing the viscosity of the polymer, a portion of the microscopic remaining oil in the corner of the oil-wet property can be moved whereas that in the corner of the water-wet property cannot be moved at all. To move the microscopic remaining oil in the corners with water-wet properties after polymer flooding, the viscosity of the displacement fluid or the displacement speed must be increased by 100-1000 times. Decreasing the interfacial tension of the oil displacement system changed the wettability of the corner residual oil, thus increasing the wetting angle. When the interfacial tension level reached 10-2 mN/m, the degree of movement of the remaining oil in the corner reached a maximum. If the interfacial tension is reduced, the degree of production of the residual oil in the corner does not change significantly. The microscopic production mechanism of the corner residual oil after polymer flooding expands the scope of the displacement streamlines in the corner.

Influence of Polymer Viscoelasticity on Microscopic Remaining Oil Production.

To investigate the impact of polymer viscoelasticity on microscopic remaining oil production, this study used microscopic oil displacement visualisation technology, numerical simulations in PolyFlow software, and core seepage experiments to study the viscoelasticity of polymers and their elastic effects in porous media. We analysed the forces affecting the microscopic remaining oil in different directions, and the influence of polymer viscoelasticity on the displacement efficiency of microscopic remaining oil. The results demonstrated that the greater the viscosity of the polymer, the greater the deformation and the higher the elasticity proportion. In addition, during the creep recovery experiment at low speed, the polymer solution was mainly viscous, while at high speed it was mainly elastic. When the polymer viscosity reached 125 mPa·s, the core effective permeability reached 100 × 10-3 µm2, and the equivalent shear rate exceeded 1000 s-1, the polymer exhibited an elastic effect in the porous medium and the viscosity curve displayed an 'upward' phenomenon. Moreover, the difference in the normal deviatoric stress and horizontal stress acting on the microscopic remaining oil increased exponentially as the viscosity of the polymer increased. The greater the viscosity of the polymer, the greater the remaining oil deformation. During the microscopic visualisation flooding experiment, the viscosity of the polymer, the scope of the mainstream line, and the recovery factor all increased. The scope of spread in the shunt line area significantly increased, but the recovery factor was significantly lower than that in the mainstream line. The amount of remaining oil in the unaffected microscopic area also decreased.

Intervention Effect of the Integration Model on Negative Emotions of Adolescents during the Outbreak of Corona Virus Disease 2019.

BACKGROUND: The World Health Organization has declared the Corona Virus Disease 2019 (COVID-19) epidemic as a public health emergency of international concern. Given the sudden infection from and extensive dispersion of COVID-19 and the absence of specific drugs, those infected are in danger if they are not treated in time. Consequently, COVID-19 has become an important factor influencing adolescents' mental health. The purpose of this study is to explore the intervention effect of the integration model on the negative emotions of adolescents during the COVID-19 epidemic. SUBJECTS AND METHODS: Adolescents were randomly selected from five middle schools in Zhejiang Province of China from May 2020 to July 2020. First, the Self-rating Anxiety Scale, Positive and Negative Affect Scale, and Psychological Well-Being Scale were used for measurement. Then, 72 patients with moderate and severe anxiety symptoms were chosen as the research objects, and the intervention and comparison time was determined to be eight weeks. The subjects were randomly divided into the experiment group (35 members) and the control group (34 members). The integration model was employed on the experiment group. RESULTS: Grade, physical condition, and sleep time are important factors influencing the anxiety level of adolescents during the COVID-19 period, and the anxiety risk of adolescents is higher during their third year of junior high school. After the intervention, the SAS score of the experiment group is lower than that of the control group, and the decrease in the SAS score is higher in the experiment group than in the control group (P<0.01). Moreover, the positive emotion score of the experiment group is higher than that of the control group, and the negative emotion score of the former is lower than that of the latter. The variances in the positive and negative emotion scores are higher in the experiment group than in the control group (P<0.01). The variance in the overall well-being index is also greater in the experiment group than in the control group (P<0.01). CONCLUSION: The intervention using the integrated model can significantly reduce negative emotions such as anxiety, increase positive emotions, and improve the overall well-being of adolescents during the epidemic period.