Experimental Study of Matrix Permeability of Gas Shale: An Application to CO 2 -Based Shale Fracturing

Chengpeng Zhang and Pathegama Gamage Ranjith
Additional contact information
Chengpeng Zhang: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne, VIC 3800, Australia
Pathegama Gamage Ranjith: Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne, VIC 3800, Australia

Energies, 2018, vol. 11, issue 4, 1-17

Abstract: Because the limitations of water-based fracturing fluids restrict their fracturing efficiency and scope of application, liquid CO 2 is regarded as a promising substitute, owing to its unique characteristics, including its greater environmental friendliness, shorter clean-up time, greater adsorption capacity than CH 4 and less formation damage. Conversely, the disadvantage of high leak-off rate of CO 2 fracturing due to its very low viscosity determines its applicability in gas shales with ultra-low permeability, accurate measurement of shale permeability to CO 2 is therefore crucial to evaluate the appropriate injection rate and total consumption of CO 2 . The main purpose of this study is to accurately measure shale permeability to CO 2 flow during hydraulic fracturing, and to compare the leak-off of CO 2 and water fracturing. A series of permeability tests was conducted on cylindrical shale samples 38 mm in diameter and 19 mm long using water, CO 2 in different phases and N 2 considering multiple influencing factors. According to the experimental results, the apparent permeability of shale matrix to gaseous CO 2 or N 2 is greatly over-estimated compared with intrinsic permeability or that of liquid CO 2 due to the Klinkenberg effect. This phenomenon explains that the permeability values measured under steady-state conditions are much higher than those under transient conditions. Supercritical CO 2 with higher molecular kinetic energy has slightly higher permeability than liquid CO 2 . The leak-off rate of CO 2 is an order of magnitude higher than that of water under the same injection conditions due to its lower viscosity. The significant decrease of shale permeability to gas after water flooding is due to the water block effect, and much longer clean-up time and deep water imbibition depth greatly impede the gas transport from the shale matrix to the created fractures. Therefore, it is necessary to substitute water-based fracturing fluids with liquid or super-critical CO 2 in clay-abundant shale formations.

Keywords: CO 2 permeability; leak-off rate; shale gas; hydraulic fracturing; water flooding; formation damage (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

Downloads: (external link)
https://www.mdpi.com/1996-1073/11/4/702/pdf (application/pdf)
https://www.mdpi.com/1996-1073/11/4/702/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:11:y:2018:i:4:p:702-:d:137306

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().