Long period, long duration seismic events during hydraulic fracture stimulation of a shale gas reservoir

2011 ◽  
Author(s):  
Indrajit Das ◽  
Mark D. Zoback
Keyword(s):  
Shale Gas ◽  
Hydraulic Fracture ◽  
Seismic Events ◽  
Gas Reservoir ◽  
Long Period ◽  
Shale Gas Reservoir ◽  
Long Duration ◽  
Stimulation Of ◽  
Hydraulic Fracture Stimulation

Long-period long-duration seismic events during hydraulic stimulation of shale and tight-gas reservoirs — Part 2: Location and mechanisms

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. KS109-KS117 ◽  
Author(s):  
Indrajit Das ◽  
Mark D. Zoback
Keyword(s):  
Fluid Pressure ◽  
Seismic Events ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Data Set ◽  
Hydraulic Stimulation ◽  
Tight Gas Reservoirs ◽  
Long Period ◽  
Long Duration ◽  
Stimulation Of

Long-period long-duration (LPLD) seismic events that have been observed during hydraulic stimulation of shale-gas and tight-gas reservoirs appear to represent slow shear slip on relatively large faults. Within the limitations of the recording geometry, we determine the areas in the reservoirs where the events are located in two case studies in the Barnett shale. In one data set, LPLD events appear to occur in the region where the density of natural fractures as well as the fluid pressure during pumping were highest. In the other data set, the LPLD events are observed to occur between two wells and seem to establish a hydraulic connection between them. In both data sets, the LPLD events occur in areas with very few located microearthquakes. A combination of factors such as high fluid pressure and/or high clay content is potentially responsible for the slowly slipping faults. The LPLD events appear to be occurring only on faults large enough to produce a sequence of slow slip events. We suggest that these slowly slipping faults contribute appreciably to the stimulation of these extremely low-permeability reservoirs and hence mapping the distribution of faults and fractures and areas with rock properties that favor slow, sustained slip, can help in optimizing production.

Nanopores to megafractures: Current challenges and methods for shale gas reservoir and hydraulic fracture characterization

2016 ◽  
Vol 31 ◽  
pp. 612-657 ◽  
Author(s):  
C.R. Clarkson ◽  
B. Haghshenas ◽  
A. Ghanizadeh ◽  
F. Qanbari ◽  
J.D. Williams-Kovacs ◽  
...  
Keyword(s):  
Shale Gas ◽  
Hydraulic Fracture ◽  
Gas Reservoir ◽  
Fracture Characterization ◽  
Shale Gas Reservoir

Rock Mechanical Properties of Shale Gas Reservoir and their Influences on Hydraulic Fracture

2013 ◽  
Author(s):  
Qinghui Li ◽  
Mian Chen ◽  
Yu Zhou ◽  
Yan Jin ◽  
Fred P. Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shale Gas ◽  
Hydraulic Fracture ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Rock Mechanical Properties

Long-period, long-duration seismic events during hydraulic stimulation of shale and tight-gas reservoirs — Part 1: Waveform characteristics

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. KS97-KS108 ◽  
Author(s):  
Indrajit Das ◽  
Mark D. Zoback
Keyword(s):  
Hydraulic Fracturing ◽  
Seismic Events ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Hydraulic Stimulation ◽  
Tight Gas Reservoirs ◽  
Long Period ◽  
Long Duration ◽  
Low Amplitude ◽  
Stimulation Of

Long-period long-duration (LPLD) seismic events are relatively low-amplitude signals that have been observed during hydraulic fracturing in several shale-gas and tight-gas reservoirs. These events are similar in appearance to tectonic tremor sequences observed in subduction zones and transform fault boundaries. LPLD events are predominantly composed of S-waves, but weaker P-waves have also been identified. In some cases, microearthquakes are observed during the events. Based on the similarity with tectonic tremors and our observations of several impulsive S-wave arrivals within the LPLD events, we interpret the LPLD events as resulting from the superposition of slow shear-slip events on relatively large faults. Most large LPLD waveforms appear to start as a relatively slower, low-amplitude precursor, lacking clear impulsive arrivals. We estimate the energy carried by the larger LPLD events to be [Formula: see text] times greater than a [Formula: see text] microseismic event that is typical of the events that occur during hydraulic stimulation. Over the course of the entire stimulation activity of five wells in the Barnett formation (each hydraulically fractured ten times), the LPLD events were found to cumulatively release over an order of magnitude higher energy than microearthquakes. The large size of these LPLD events, compared to microearthquakes, suggests that they represent slip on relatively large faults during stimulation of these extremely low-permeability reservoirs. Moreover, they imply that the accompanying slow slip on faults, probably mostly undetected, is a significant deformation process during multistage hydraulic fracturing.

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