Journal of Environmental Biology

Potential evaluation of CO₂ storage and enhanced oil recovery of

tight oil reservoir in the Ordos Basin, China

Xiaofeng Tian^1*, Linsong Cheng¹, Renyi Cao¹, Miaoyi Zhang², Qiang Guo³, Yimin Wang⁴, Jian Zhang⁵ and Yu Cui⁶

¹Department of Petroleum Engineering, China University of Petroleum-Beijing, Beijing, 102249, China

²Department of Geoscience, China University of Petroleum-Beijing, Beijing, 102249, China

³Department of Petroleum Engineering, Missouri University of Science and Technology, Rolla, Missouri, 65409, USA

⁴Department of Engineering and Technology, Tianjin Branch of China National Offshore Oil Corporation, Tianjin, 300452, China

⁵Department of Australia Project Technology, Sinopec International Exploration and Production Corporation, Beijing, 100086, China

⁶Department of Exploration and Evaluation in Beidagang, Exploration and Development Research Institute of Dagang Oilfield Company of Petrochina, Tianjin, 300280, China

*Corresponding Author?s Email : txf5160@163.com

Publication Data

Paper received:

01 June 2014

Revised received:

30 September 2014

Re-revised received:

01 January 2015

Accepted:

07 February 2015

Abstract

Carbon -di-oxide (CO₂) is regarded as the most important greenhouse gas to accelerate climate change and ocean acidification. The Chinese government is seeking methods to reduce anthropogenic CO₂ gas emission. CO₂ capture and geological storage is one of the main methods. In addition, injecting CO₂ is also an effective method to replenish formation energy in developing tight oil reservoirs. However, exiting methods to estimate CO₂ storage capacity are all based on the material balance theory. This was absolutely correct for normal reservoirs. However, as natural fractures widely exist in tight oil reservoirs and majority of them are vertical ones, tight oil reservoirs are not close. Therefore, material balance theory is not adaptive. In the present study, a new method to calculate CO₂ storage capacity is presented. The CO₂ effective storage capacity, in this new method, consisted of free CO₂, CO₂ dissolved in oil and CO₂ dissolved in water. Case studies of tight oil reservoir from Ordos Basin was conducted and it was found that due to far lower viscosity of CO₂ and larger solubility in oil, CO2 could flow in tight oil reservoirs more easily. As a result, injecting CO₂ in tight oil reservoirs could obviously enhance sweep efficiency by 24.5% and oil recovery efficiency by 7.5%. CO₂ effective storage capacity of Chang 7 tight oil reservoir in Longdong area was 1.88?10⁷ t. The Chang 7 tight oil reservoir in Ordos Basin was estimated to be 6.38?1011 t. As tight oil reservoirs were widely distributed in Songliao Basin, Sichuan Basin and so on, geological storage capacity of CO₂ in China is potential. ??  

 Key words

CO₂ Effective storage capacity, Enhance oil recovery, Tight oil reservoirs

Copyright ? 2015 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).