A Study on the Mechanism of Urea-assisted Steam Flooding in Heavy Oil Reservoirs

Document Type: Research Paper


1 Zhongyuan Oilfield Branch Company, Sinopec, Puyang, Henan Province, 457001, P.R. of China

2 School of Foreign Languages, Xi’an Shiyou University, Xi’an, Shaanxi Province, 710065, P. R. of China

3 Oil and Gas Development Corporation, Zhongyuan Petroleum Engineering Ltd. Sinopec, Puyang, Henan Province, 457001, P. R. of China

4 School of Petroleum, China University of Petroleum, Qingdao, Shandong Province, 266580, P. R. of China


The Biqian-10 block, located in Henan Oilfield of Sinopic, contains many thin and interbedded reservoirs, which have been operated by cyclic steam stimulation for 20 years or more. Therefore, it is a challenge to implement the conventional steam flooding. In order to improve the recovery of steam flooding, urea was used to assist steam flooding. Urea can decompose into CO2 and NH3, which are beneficial to enhance oil recovery (EOR). For the sake of exactly quantifying the mechanism of urea assisted steam flooding (UASF), the UASF model was built according to the experimental results. The simulation results show that CO2 is the key point for EOR, and its pressurization function is more effective than the decrease in oil viscosity by dissolving CO2. The emulsification of crude oil for NH3 is weak in interfacial tension tests; thus the effect of emulsification can be ignored in the simulation. The UASF can improve the recovery by about 17.4%, which is 6.8% higher than steam flooding.


      [1]     Sedaee Sola B., “Feasibility Experimental Investigation of Steam/Methane Flooding in a Heavy Oil Reservoir,” SPE 91968-MS, presented at the SPE International Petroleum Conference in Mexico, Puebla Pue., Mexico, 2004.

      [2]     Naderi Kh. and Babadagli T., “Experimental Analysis of Heavy Oil Recovery and CO2 Storage by Alternate Injection of Steam and CO2 in Deep Naturally Fractured Reservoir,” SPE 146738-MS, presented at the SPE Heavy Oil Conference Canada, Calgary, Alberta, Canada, 2012.

      [3]     Yongrong G., Shangqi L., and Dehuang Sh., “Improving Oil Recovery by Adding N2 in SAGD Process for Super-heavy Crude Reservoir with Top-Water,” SPE 114590-MS, presented at the SPE Russian Oil and Gas Technical Conference and Exhibition, Moscow, Russia, 2008.

      [4]     Zhong L., Dong Z., and Hou J., “Investigation on Principles of Enhanced Offshore Heavy Oil Recovery by Co-injection of Steam with Flue Gas,” SPE 165231-MS, presented at the 2013 SPE Enhanced Oil Recovery Conference, Kuala Lumpur, Malaysia, 2013.

      [5]     Shen D., Zhang Y., and Zhang X., “Study and Application of Adding Additive to Improve Heavy Oil Recovery,” Petroleum Journal, 6, 2004 (in Chinese).

      [6]     Zhang X., Zhang Y., and Yue Q., “Conformance Control of CSS and Steam Drive Process with a Carbamide Surfactant,” JCPT, presented at the 7th Canadian International Petroleum Conference (the 57th Annual Technical Meeting of the Petroleum Society), in Calgary, Alberta, 2006.

      [7]     De-huang SH., Jian-jun X., and Xiao-chun W., “Experimental Study and Application of Urea in Steam Flooding of Heavy Oil Reservoir,” Special Oil and Gas Reservoirs, 2005, 12(2), 85-87 (in Chinese).

      [8]     Hong-kun L., Wei-juan Y., and Jun-hu Z., “Investigation on Thermal Decomposition Characteristics of Urea Solution under High Temperature,” Proceedings of the CSEE, 2010, 30(17), 35-40 (in Chinese).

      [9]     Chung Frank T. H., Jones Ray A., and Nguyen Hai T., “Measurements and Correlations of the Physical Properties of CO2/Heavy-crude-oil Mixtures [J],” SPE 15080-PA., 1988, 3, 822-828.

    [10]    King H. H., Hall J. L., and Ware G. C., “A Study of the Density, Surface Tension and
Adsorption in the Water-ammonia System at 20
,” Journal of American Chemical Society, 1930, 52(12), 5128-5135.

    [11]    Tong-yao Z., Wei-yu F., and Guo-zhi N., “Study on Interaction of Heavy Oil Polar Component and Emulsifier in Heavy Crude Oil-in-water Emulsion,” Journal of China University of Petroleum, 2006, 30(5), 101-105 (in Chinese).

    [12]    Ping J., Ji-jiang G, and Gui-cai Z., “Influence Factor on Oil Recovery Efficiency for Chemical Flooding of Heavy Oil Reservoir,” Journal of China University of Petroleum, 2011, 35(2), 166-169 (in Chinese).