Effect of Injection Site on Fault Activation and Seismicity during Hydraulic Fracturing

Energies. 2017;10(10):1619 DOI 10.3390/en10101619

 

Journal Homepage

Journal Title: Energies

ISSN: 1996-1073 (Print)

Publisher: MDPI AG

LCC Subject Category: Technology

Country of publisher: Switzerland

Language of fulltext: English

Full-text formats available: PDF, HTML

 

AUTHORS

Zhaohui Chong (Key Laboratory of Deep Coal Resource, Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China)
Xuehua Li (Key Laboratory of Deep Coal Resource, Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China)
Xiangyu Chen (Key Laboratory of Deep Coal Resource, Ministry of Education of China, School of Mines, China University of Mining and Technology, Xuzhou 221116, China)

EDITORIAL INFORMATION

Blind peer review

Editorial Board

Instructions for authors

Time From Submission to Publication: 11 weeks

 

Abstract | Full Text

Hydraulic fracturing is a key technology to stimulate oil and gas wells to increase production in shale reservoirs with low permeability. Generally, the stimulated reservoir volume is performed based on pre-existing natural fractures (NF). Hydraulic fracturing in shale reservoirs with large natural fractures (i.e., faults) often results in fault activation and seismicity. In this paper, a coupled hydro-mechanical model was employed to investigate the effects of injection site on fault activation and seismicity. A moment tensor method was used to evaluate the magnitude and affected areas of seismic events. The micro-parameters of the proposed model were calibrated through analytical solutions of the interaction between hydraulic fractures (HF) and the fault. The results indicated that the slip displacement and activation range of the fault first decreased, then remained stable with the increase in the distance between the injection hole and the fault (Lif). In the scenario of the shortest Lif (Lif = 10 m), the b-value—which represents the proportion of frequency of small events in comparison with large events—reached its maximum value, and the magnitude of concentrated seismic events were in the range of −3.5 to −1.5. The frequency of seismic events containing only one crack was the lowest, and that of seismic events containing more than ten cracks was the highest. The interaction between the injection-induced stress disturbance and fault slip was gentle when Lif was longer than the critical distance (Lif = 40–50 m). The results may help optimize the fracturing treatment designs during hydraulic fracturing.