Study on imbibition during the CO2 enhanced oil recovery in fractured tight sandstone reservoirs

CO2 enhanced oil recovery (CO2-EOR) is a key technology for improving the oil recovery of fractured tight reservoirs, and imbibition has been recognized as an important mechanism for oil recovery in low-permeability reservoirs. To clarify the imbibition role and influencing factors during the CO2-EOR process in fractured tight oil reservoirs and also improve the EOR mechanism, a high-temperature and high-pressure CO2 imbibition experiment was performed based on the nuclear magnetic resonance technology. The results show that high pressure and high permeability are beneficial to imbibition efficiency. The salinity of the imbibition fluid is not very sensitive to the imbibition recovery. In addition, the CO2 increases the imbibition speed and can also significantly improve the production rate and oil recovery. It is beneficial to increase the CO2 concentration to shorten the imbibition equilibrium time and enhance oil recovery. According to the results of the nuclear magnetic resonance study, although the nanopore can provide a greater imbibition force, the oil flow resistance is also larger, but CO2 can reduce the flow resistance of oil and be conducive to oil production in smaller pores. The inclusion of imbibition into the research category of CO2-EOR mechanism will be more in line with field practice and more scientific in fractured tight reservoirs, thus providing theoretical support for the development and improvement of the CO2-EOR technology.Document Type: Original articleCited as: Wang, Y., Shang, Q., Guo, J., Zhou, L. Study on imbibition during the CO2 enhanced oil recovery in fractured tight sandstone reservoirs. Capillarity, 2023, 7(3): 47-56. https://doi.org/10.46690/capi.2023.06.0

Diagnotic Value of the Combined Determination of Telomerase Activity in Induced Sputum, Pleural Effusion and Fiberobronchoscopic Biopsy Samples in Lung Cancer

Background and objective It has been proven that telomerase activation correlates with the carcinogenesis, aggressiveness and turnover of lung cancer. Telomerase is one of the improtant molecular biomarkers for diagnosis and targeting therapy in lung cancer. The aim of this study is to investigate the diagnostic value of the combined determination of telomerase activity in induced sputum, pleural effusion and fiberobronchoscopic biopsy in lung cancer patients. Methods The technique of TRAP (telomeric repeat amplification protocal)-PCR-ELISA was employed to detect telomease levels of induced sputum, pleural effusion and fiberobronchoscopic biopsy in 80 lung cancer patients with pleural effusion and 50 benign pulmonary disease patients with pleural effusion. Results Telomemse levels of induced sputum, pleural effusion and fiberobronchoscopic biopsy were all significantly higher in patients with lung cancer than those with benign pulmonary disease (P < 0.001). There was no significant difference in the level of telomerase activity between different pathologic types (P>0.05). The sensitivity of induced sputum, pleural effusion and fiberobronchoscopic biopsy were 62.5% (50/80), 46.3% (37/80) and 60.0% (48/80), respectively. The specificity were 72.0% (36/50), 66.0% (33/50) and 70.0% (35/50), respectively. The overall accuracy were 66.2% (86/130), 53.8% (70/130) and 63.8% (83/130), respectively. The sensitivity, specificity and overall accuracy of combined induced sputum, pleural effusion and fiberobronchoscopic biopsy were 85.0% (68/80), 78.0% (39/50) and 82.3% (107/130), respectively. The sensitivity of telomease level in combined detection for diagnosis of lung cancer was much higher than that in single sample detection (P < 0.01). Conclusion The sensitivity of telomease activity in combined three samples was the highest. It can further improve the accuracy for the diagnosis of lung cancer with pleural effusion