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Title: Effect of the Injection Pressure on Enhancing Oil Recovery in Shale Cores during the CO 2 Huff-n-Puff Process When It Is above and below the Minimum Miscibility Pressure

Abstract

In CO 2 injection, there is a minimum miscibility pressure (MMP) above that CO 2 can be miscible with oil, so that oil recovery will be high. This work is to investigate the effect of the injection pressure on enhanced oil recovery in shale oil cores under huff-n-puff CO 2 injection, when the pressure is above and below the MMP. We first estimated the MMP for a Wolfcamp oil using slimtube tests. The slimtube test results showed that the estimated MMP for the CO 2–Wolfcamp crude oil system was about 1620 psi at 104 °F. After that, we conducted 15 CO 2 huff-n-puff experiments using three different Wolfcamp shale cores at pressures below and above the MMP. These pressures were 1200, 1600, 1800, 2000, and 2400 psi. Each huff-n-puff test has 7 cycles. The huff-n-puff experiments for three cores showed that, below the MMP, the injection pressure had a significant effect on enhancing oil recovery. Higher than the MMP, the increased pressure further increased the oil recovery until the injection pressure was about 200 psi higher than the MMP. In the extremely low-permeability shale oil cores, additional pressure is needed to push gas into the deeper core to be misciblemore » with the crude oil inside the core. The results indicated that, to have a high oil recovery in shale oil reservoirs during the CO 2 huff-n-puff process, the injection pressure should be higher (at least 200 psi in this case) than the MMP estimated from slimtube tests.« less

Authors:
ORCiD logo [1];  [1];  [2]
  1. Texas Tech Univ., Lubbock, TX (United States)
  2. Texas Tech Univ., Lubbock, TX (United States); Southwest Petroleum Univ., Chengdu (China)
Publication Date:
Research Org.:
Texas Tech Univ., Lubbock, TX (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1534481
Grant/Contract Number:  
FE0024311
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Energy and Fuels
Additional Journal Information:
Journal Volume: 31; Journal Issue: 4; Journal ID: ISSN 0887-0624
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
04 OIL SHALES AND TAR SANDS; energy & fuels; engineering; lipids; petrochemicals; shale; oil recovery; permeability

Citation Formats

Li, Lei, Zhang, Yao, and Sheng, James J. Effect of the Injection Pressure on Enhancing Oil Recovery in Shale Cores during the CO2 Huff-n-Puff Process When It Is above and below the Minimum Miscibility Pressure. United States: N. p., 2017. Web. doi:10.1021/acs.energyfuels.7b00031.
Li, Lei, Zhang, Yao, & Sheng, James J. Effect of the Injection Pressure on Enhancing Oil Recovery in Shale Cores during the CO2 Huff-n-Puff Process When It Is above and below the Minimum Miscibility Pressure. United States. https://doi.org/10.1021/acs.energyfuels.7b00031
Li, Lei, Zhang, Yao, and Sheng, James J. Wed . "Effect of the Injection Pressure on Enhancing Oil Recovery in Shale Cores during the CO2 Huff-n-Puff Process When It Is above and below the Minimum Miscibility Pressure". United States. https://doi.org/10.1021/acs.energyfuels.7b00031. https://www.osti.gov/servlets/purl/1534481.
@article{osti_1534481,
title = {Effect of the Injection Pressure on Enhancing Oil Recovery in Shale Cores during the CO2 Huff-n-Puff Process When It Is above and below the Minimum Miscibility Pressure},
author = {Li, Lei and Zhang, Yao and Sheng, James J.},
abstractNote = {In CO2 injection, there is a minimum miscibility pressure (MMP) above that CO2 can be miscible with oil, so that oil recovery will be high. This work is to investigate the effect of the injection pressure on enhanced oil recovery in shale oil cores under huff-n-puff CO2 injection, when the pressure is above and below the MMP. We first estimated the MMP for a Wolfcamp oil using slimtube tests. The slimtube test results showed that the estimated MMP for the CO2–Wolfcamp crude oil system was about 1620 psi at 104 °F. After that, we conducted 15 CO2 huff-n-puff experiments using three different Wolfcamp shale cores at pressures below and above the MMP. These pressures were 1200, 1600, 1800, 2000, and 2400 psi. Each huff-n-puff test has 7 cycles. The huff-n-puff experiments for three cores showed that, below the MMP, the injection pressure had a significant effect on enhancing oil recovery. Higher than the MMP, the increased pressure further increased the oil recovery until the injection pressure was about 200 psi higher than the MMP. In the extremely low-permeability shale oil cores, additional pressure is needed to push gas into the deeper core to be miscible with the crude oil inside the core. The results indicated that, to have a high oil recovery in shale oil reservoirs during the CO2 huff-n-puff process, the injection pressure should be higher (at least 200 psi in this case) than the MMP estimated from slimtube tests.},
doi = {10.1021/acs.energyfuels.7b00031},
url = {https://www.osti.gov/biblio/1534481}, journal = {Energy and Fuels},
issn = {0887-0624},
number = 4,
volume = 31,
place = {United States},
year = {2017},
month = {3}
}

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Works referencing / citing this record:

Experimental investigation on influencing factors of CO 2 huff and puff under fractured low‐permeability conditions
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A new approach for predicting oil recovery factor during immiscible CO2 flooding in sandstones using dimensionless numbers
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Optimization Strategy to Reduce Asphaltene Deposition-Associated Damage During CO$$_2$$ Huff-n-Puff Injection in Shale
journal, January 2019


Nanomodel visualization of fluid injections in tight formations
journal, January 2018


Experimental Study on Reducing CO2–Oil Minimum Miscibility Pressure with Hydrocarbon Agents
journal, May 2019


Huff-n-Puff Experimental Studies of CO2 with Heavy Oil
journal, November 2019