Experimental investigation of propagation mechanisms and fracture morphology for coalbed methane reservoirs

Fracture propagation mechanisms in coalbed methane (CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fractures in coal specimens at different angles between the face cleat and the maxim...

Full description

Saved in:
Bibliographic Details
Published in:Petroleum science 2018-11, Vol.15 (4), p.815-829
Main Authors: Ai, Chi, Li, Xiao-Xuan, Zhang, Jun, Jia, Dan, Tan, Wen-Jing
Format: Article
Language:English
Subjects:
Butt cleat
Coal
Coalbed methane
Coalbed methane reservoir
Crack initiation
Crack propagation
Earth and Environmental Science
Earth Sciences
Economics and Management
Energy Policy
Fracture mechanics
Fracture morphology
Hydraulic fracturing
Industrial and Production Engineering
Industrial Chemistry/Chemical Engineering
Interactions
Methane
Mineral Resources
Morphology
Original Paper
Propagation
Propagation mechanisms
Reservoirs
Step-like fractures
Viscosity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Fracture propagation mechanisms in coalbed methane (CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fractures in coal specimens at different angles between the face cleat and the maximum horizontal principal stress were investigated with hydraulic fracturing tests. The results indicate that the interactions between the hydraulic fractures and the cleat system have a major effect on fracture networks. “Step-like” fractures were formed in most experiments due to the existence of discontinuous butt cleats. The hydraulic fractures were more likely to divert or propagate along the butt cleat with an increase in the angles and a decrease in the horizontal principal stress difference. An increase in the injection rate and a decrease in the fracturing fluid viscosity were more conducive to fracture networks. In addition, the influence on fracture propagation of the residual coal fines in the wellbore was also studied. The existence of coal fines was an obstacle in fracturing, and no effective connection can be formed between fractures. The experimental investigation revealed the fracture propagation mechanisms and can provide guidance for hydraulic fracturing design of CBM reservoirs.
ISSN:1672-5107
1995-8226
DOI:10.1007/s12182-018-0252-z