An Experimental Investigation of Feasibility of Gas Huff and Puff for Recovering Crude Oil with Different Viscosities

Document Type: Research Paper

Authors

1 China University of Petroleum (East China)

2 China Universit of Petroleum (East China)

3 China Petroleum & Chemical Corporation

Abstract

Investigating multi cyclic gas (N2 and CO2) huff and puff have been conducted by long sandpack simulations with four different crude oils from Jiangsu oilfield. According to the production differential pressure and the production regularity during huff and puff, the production process was divided into three sections; the first one is free gas production section; the second section is low viscous oil production section, and the third one is gas driving exploitation section. According to the results, the production decreases with the increase of cycle times at a certain backpressure, and the effect of multi-cycle huff and puff is improved as the backpressure decreases. In the same cycle, the oil production increases as the backpressure declines. In the first huff and puff cycle, positive synergistic effects are generated while CO2 and N2 are being mixed, and there is an optimum ratio between them. The amount of CO2 in the optimum ratio increases as the backpressure rises. The effect of single gas is better than that of mixed gas in multi-cycle huff and puff, and the effect of CO2 is better than that of N2. The effect of huff and puff is not influenced by the injection mode. At a high backpressure, the huff-and-puff effect becomes better as the oil viscosity increases, but at low backpressure, it becomes worse with an increase in oil viscosity. The huff-and-puff effect also gets worse as the temperature rises. The oil recovery degree is improved as the CO2 injection amount increases, but there is an optimal oil exchange ratio. The depressurization process should be neither too quick nor too slow in the CO2 huff-and-puff process. The cyclic oil production is improved with the increase of injection rate while the average injection rate is lower than 90 L/min. The equilibrium time of CO2 is shorter than that of N2. The economic return of N2 huff and puff is better than that of CO2 at high producing pressure drop, and light oil has higher economic returns than heavy oil.

Keywords


REFERENCES

Momger T. G. and Coma J. M., “A Laboratory and Field Evaluation of the CO2 Huff-n-Puff Process for Light-Oil Recovery,” SPE Reservoir Engineering, 1988, 3, 1168-1176.

Haskin H. K. and Alston R. B., “An Evaluation of CO2 Huff-n-Puff Tests in Texas,” SPE Reservoir Engineering, 1989, 2(41), 177-184

Tang X., Li G., Wang R., and Wu X., “Innovative In-situ Natural Gas Huff and Puff in Same Well Bore for Cost-Effective Development: A Case Study in Sudan,” SPE 144836 Presented at SPE Enhanced Oil Recovery Conference, Kuala Lumpur, Malaysia, 2011.

Rubin B., “Accurate Simulation of Non Darcy Flow in Stimulated Fractured Shale Reservoirs,” paper SPE 132093 presented at the SPE Western Regional Meeting, Anaheim, California, 2010.

Wan T., Sheng J. J., and Soliman M. Y., 2013b. “Evaluation of the EOR Potential in Fractured Shale Oil Reservoirs by Cyclic Gas Injection,” In Paper SPE 168880 or URTeC1611383 Presented at the Unconventional Resources Technology Conference Held in Denver, Colorado, USA, 2013.

Sheng J. J. and Chen K., “Evaluation of the EOR Potential of Gas and Water Injection in Shale Oil Reservoirs,” Journal of Unconventional Oil and Gas Resources, 2014, 5, 1-9.

Yu W., Lashgari H., and Sepehrnoori K., “Simulation Study of CO2 Huff-n-Puff Process in Bakken Tight Oil Reservoirs,” SPE 169575 in SPE Western North American and Rocky Mountain Joint Meeting, Denver, Colorado, USA, 2014.

Yu W., Al-Shalabi E. W., and Sepehrnoori K., “A Sensitivity Study of Potential CO2 Injection for Enhanced Gas Recovery in Barnett Shale Reservoirs,” SPE 169012 in SPE Unconventional Resources Conference, Woodlands, Texas, USA, 2014.

Chen C., Balhoff M. T., and Mohanty K. K., “Effect of Reservoir Heterogeneity on Primary Recovery and CO2 Huff ’n’ Puff Recovery in Shale-oil Reservoirs,” SPEREE, 2014, 17(3), 404-413.

Vinassa M., Cudjoe S. E., Gomes J. H. B., and Ghahfarokhi R. B., “A Comprehensive Approach to Sweet-Spot Mapping for Hydraulic Fracturing and CO2 Huff-n-Puff Injection in Chattanooga Shale Formation,” SPE 175952 Presented at SPE/CSUR Unconventional Resources Conference Calgary, Alberta, Canada, 2015.

Sheng J. J. and Chen K., “Evaluation of the EOR Potential of Gas and Water Injection in Shale Oil Reservoirs,” Journal of Unconventional Oil and Gas Resources, 2014, 5, 1-9.

Sheng J. J., “Enhanced Oil Recovery in Shale Reservoirs by Gas Injection,” Journal of Natural Gas Science and Engineering, 2015, 22, 252-259.

Yu Y. and Sheng J., “An Experimental Investigation of the Effect of Pressure Depletion Rate on Oil Recovery from Shale Cores by Cyclic N2 Injection.” SPE-178494 prepared for presentation at the Unconventional Resources Technology Conference held in San Antonio, Texas, USA, 2015.

Meng X., Yu Y., and Sheng J. J., “An Experimental Study on Huff-n-Puff Gas Injection to Enhance Condensate Recovery in Shale Gas Reservoirs,” SPE 178540 Presented at Unconventional Resources Technology Conference, San Antonio, Texas, 2015.

Yu Y. and Sheng J. J., “An Experimental Investigation of the Effect of Pressure Depletion Rate on Oil Recovery from Shale Cores by Cyclic N2 Injection,” SPE 178494 in SPE Unconventional Resources Technology Conference, San Antonio, Texas, 2015.

Gamadi T. D., Sheng J. J., and Soliman M. Y., “An Experimental Study of Cyclic Gas Injection to Improve Shale Oil Recovery,” SPE 166334 in SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, USA, 2013.

Gamadi T. D., Sheng J. J., Soliman M. Y., Menouar H., et al., “An Experimental Study of Cyclic CO2 Injection to Improve Shale Oil Recovery,” SPE 169142 in SPE Improved Oil Recovery Symposium, Tulsa, Oklahoma, USA, 2014.

Zhengxiang W., Jinhua M., Ruimin G., et al., “Optimizing Cyclic CO2 Injection for Low-Permeability Oil Reservoirs through Experimental Study,” SPE 167193 prepared for presentation at the SPE Unconventional Resources Conference-Canada held in Calgary, Alberta, Canada, 2013.

Smith L. K., MacGowan D. B., and Surdam R. C., “Scale Prediction during CO2 Huff-n-Puff Enhanced Recovery, Crooks Gap Field, Wyoming,” Paper SPE 21838 presented at the Rocky Mountain Regional Meeting and Low-permeability Reservoirs Symposium, Denver, Colorado, 1991.

Crawford H. R., Neill G. H., Bucy B. J., and Crawford P. B., “Carbon Dioxide-a Multipurpose Additive for Effective Well Stimulation,” JPT, 1963, 3(15), 237-242

Sayegh S. G., Najman J., and Wang S. T., “Multiple Contact Phase Behavior in the Displacement of Crude Oil with Nitrogen and Enriched Nitrogen,” Jour. Can. Pet. Tech., 1987, 26(6), 31-39.

Sayegh S. G., Wang S. T., and Fosti J. E., “Recovery of Crude Oil by Nitrogen Injection-Laboratory Displacement Data,” Jour. Can. Pet. Tech., 1988, 27(6), 74-79.

Vicencio O. A., Sepehrnoori K., and Miller M. A., “Simulation of Nitrogen Injection into Naturally Fractured Reservoirs,” Paper SPE 92110 presented at the 2004 SPE International Petroleum Conference held in Mexico Puebla, Mexico, 2004.