Experimental Investigation on Propagation Behavior of Hydraulic Fractures in Coal Seam during Refracturing
Joint Authors
Sun, Xun
Zhang, Shicheng
Ma, Xinfang
Zou, Yushi
Lin, Guanyu
Source
Issue
Vol. 2019, Issue 2019 (31 Dec. 2019), pp.1-15, 15 p.
Publisher
Hindawi Publishing Corporation
Publication Date
2019-05-02
Country of Publication
Egypt
No. of Pages
15
Main Subjects
Abstract EN
Refracturing is an effective technology for reinstituting a percolation path and improving the fracture conductivity in coal measure strata.
Hydraulic fracture (HF) propagation is complicated due to the presence of cleats and stress change caused by pore pressure changes.
Many scholars have studied HF propagation in the initial fracturing of coal, but the refracturing in coal seams is rarely mentioned.
In this study, laboratory refracturing experiments were conducted on large natural coal specimens under various triaxial stress states to investigate the propagation of HFs in coal seams.
The mechanical properties of coal were tested before refracturing.
The maximum and the minimum horizontal principal stresses are inverted to simulate the stress change caused by the production and pore pressure reduction of the stress condition after initial fracturing.
Experimental results showed three different types of HF initiation and propagation during refracturing: (1) under low horizontal stress differences (0-2 MPa), HF propagated along the cleats, and no new HFs were formed on the walls of the initial HFs regardless of changes in the horizontal stress; (2) under high horizontal stress differences (4–8 MPa) with no stress inversion, a major HF was initiated parallel to the orientation of maximum horizontal stress during initial fracturing; new branches propagated along cleats in the orientation of the minimum horizontal stress during refracturing; and (3) under high horizontal stress differences (4–8 MPa) with maximum and minimum horizontal stress inversions, the main HF formed along the orientation of the maximum horizontal stress, and a new HF perpendicular to the initial HF was formed during refracturing.
Multiple factors affect fracture morphology during refracturing.
Cleats affect the HF growth path and the creation of new branches.
The in situ stress determines the initiation and propagation of new HFs.
American Psychological Association (APA)
Sun, Xun& Zhang, Shicheng& Ma, Xinfang& Zou, Yushi& Lin, Guanyu. 2019. Experimental Investigation on Propagation Behavior of Hydraulic Fractures in Coal Seam during Refracturing. Geofluids،Vol. 2019, no. 2019, pp.1-15.
https://search.emarefa.net/detail/BIM-1153317
Modern Language Association (MLA)
Sun, Xun…[et al.]. Experimental Investigation on Propagation Behavior of Hydraulic Fractures in Coal Seam during Refracturing. Geofluids No. 2019 (2019), pp.1-15.
https://search.emarefa.net/detail/BIM-1153317
American Medical Association (AMA)
Sun, Xun& Zhang, Shicheng& Ma, Xinfang& Zou, Yushi& Lin, Guanyu. Experimental Investigation on Propagation Behavior of Hydraulic Fractures in Coal Seam during Refracturing. Geofluids. 2019. Vol. 2019, no. 2019, pp.1-15.
https://search.emarefa.net/detail/BIM-1153317
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references
Record ID
BIM-1153317