Back azimuth constrained double-difference seismic location and tomography for downhole microseismic monitoring

Chen, Yukuan; Zhang, Haijiang; Miao, Yuanyuan; Zhang, Yinsheng; Liu, Qiang

doi:10.1016/j.pepi.2016.10.003

Cited by 36 publications

(16 citation statements)

References 32 publications

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“…Figure 2a shows that the earthquakes are generally within the low V p and V s zones. Based on the results of laboratory test (Christensen, 1989) and real case study (Chen et al, 2017), we speculate that the infiltration of high-pressure fluids into the fault zones is the cause of the velocity reduction. It can be seen that the V p /V s ratio in the earthquake source regions (i.e., 1.608-1.626) is about 6-7% lower than the background value of 1.73.…”

Section: Geophysical Research Lettersmentioning

confidence: 94%

Hydraulic Fracturing Induced Seismicity in the Southern Sichuan Basin Due to Fluid Diffusion Inferred From Seismic and Injection Data Analysis

Tan

Zhang

et al. 2020

Geophysical Research Letters

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In the southern Sichuan Basin, China, the recent increase in the seismic activity has been suspected to be related to hydraulic fracturing stimulation for producing the shale gas. In this study, we used the monitoring data from a local seismic network within the shale gas blocks to study the earthquakes near the shale gas production wells that have detailed injection data. Comparison of the timing of earthquakes and stimulation schedule of the studied well pads indicates an apparent correlation between the seismic activity and hydraulic fracturing. The results of seismic velocity tomography reveal that the reactivation of preexisting faults due to fluid diffusion is the primary cause of the observed earthquakes. Focal mechanism analysis combined with geomechanical modeling indicates that the increased pore pressures resulted from hydraulic fracturing are sufficient to trigger seismic slip on the faults.

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Section: Geophysical Research Lettersmentioning

confidence: 94%

Hydraulic Fracturing Induced Seismicity in the Southern Sichuan Basin Due to Fluid Diffusion Inferred From Seismic and Injection Data Analysis

Tan

Zhang

et al. 2020

Geophysical Research Letters

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“…We apply the new reverse‐time imaging method to a downhole microseismic data set to characterize potential fractures and impedance interfaces in the proximity of the microseismic events. This downhole microseismic data set is from a shale gas HF treatment (Chen et al, ). The target shale formation is located at about 2,400 m in depth, and in total 15 stages of HF are performed.…”

Section: Application To a Downhole Field Data Setmentioning

confidence: 99%

“…Figure shows the trajectories of fracturing well and monitoring well, as well as the locations of treatment stages and borehole geophones. Chen et al () determined accurate microseismic locations for Stages 10–13 and inverted for the velocity model by the back‐azimuth constrained double‐difference location and tomography method. At 2.432 km in depth, there is an obvious low‐velocity anomaly to the southwest of the monitoring well (Figure a), which is likely caused by the existence of fluids and fractures.…”

Section: Application To a Downhole Field Data Setmentioning

confidence: 99%

“…Using various detection algorithms such as the widely used STA/LTA (Short Term Average over Long Term Average) method (Vaezi & Van Der Baan, ), microseismic events could be found from the continuous data. The detected microseismic events can then be located by traveltime‐based or migration‐based location methods (Chen et al, ; Nakata & Beroza, ). From the temporal and spatial distributions, we can evaluate the HF process and characterize the spatial attributes of the fractures, from which the stimulated reservoir volume can be estimated and the effectiveness of the treatment can be assessed.…”

Section: Introductionmentioning

confidence: 99%

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Source‐Independent Passive Seismic Reverse‐Time Structure Imaging With Grouping Imaging Condition: Method and Application to Microseismic Events Induced by Hydraulic Fracturing

et al. 2020

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Seismic imaging with active seismic sources can be used to image subsurface structures such as faults, fractures, and layer interfaces with higher resolutions than tomographic methods. However, for characterizing large‐scale three‐dimensional structures, oftentimes it is too expensive and thus impractical to conduct active seismic survey. Seismic imaging using passive sources has been used to image structures through the “pseudoactive” source imaging by assuming source information is known. However, in practice there exist some uncertainties on source information including location, origin time, source time function, and radiation pattern, which can inevitably affect the final imaging result. In this study, we propose a new source‐independent passive seismic imaging method based on reverse‐time imaging with converted waves and a new imaging condition. This method uses the interference between P and S waves at conversion points for structure imaging by back‐propagating seismograms recorded by all receivers. Since no forward modeling is needed in this method, source information is not needed. A new grouping imaging condition is proposed to improve the image resolution, in which seismic receivers are divided into several groups and the separated P and S wavefields of different groups are multiplied and then stacked over time to get an image. We test the new method on both synthetic and real data sets based on a downhole microseismic system that is used for monitoring a shale gas hydraulic fracturing treatment. The results show that the proposed passive seismic imaging method does not depend on knowing source information and can achieve higher imaging resolution.

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“…Compared to surface monitoring, the obvious advantage of downhole microseismic monitoring is that the detection is nearer the reservoir leading to a high S/N ratio, many more P and S waves, etc. for determining accurate event locations (Song et al, 2013;Chen et al, 2017;Hawthorne and Ampuero, 2017). Fig.…”

Section: Microseismic Monitoring Techniquementioning

confidence: 99%

Downhole Microseismic Source Location Based on a Multi‐Dimensional DIRECT Algorithm for Unconventional Oil and Gas Reservoir Exploration

Yin

Tao

Zheng

et al. 2019

Acta Geologica Sinica (Eng)

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Downhole microseismic data has the significant advantages of high signal-to-noise ratio and well-developed P and S waves and the core component of microseismic monitoring is microseismic event location associated with hydraulic fracturing in a relatively high confidence level and accuracy. In this study, we present a multidimensional DIRECT inversion method for microseismic locations and applicability tests over modeling data based on a downhole microseismic monitoring system. Synthetic tests inidcate that the objective function of locations can be defined as a multi-dimensional matrix space by employing the global optimization DIRECT algorithm, because it can be run without the initial value and objective function derivation, and the discretely scattered objective points lead to an expeditious contraction of objective functions in each dimension. This study shows that the DIRECT algorithm can be extensively applied in real downhole microseismic monitoring data from hydraulic fracturing completions. Therefore, the methodology, based on a multidimensional DIRECT algorithm, can provide significant high accuracy and convergent efficiency as well as robust computation for interpretable spatiotemporal microseismic evolution, which is more suitable for real-time processing of a large amount of downhole microseismic monitoring data.

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Back azimuth constrained double-difference seismic location and tomography for downhole microseismic monitoring

Cited by 36 publications

References 32 publications

Hydraulic Fracturing Induced Seismicity in the Southern Sichuan Basin Due to Fluid Diffusion Inferred From Seismic and Injection Data Analysis

Hydraulic Fracturing Induced Seismicity in the Southern Sichuan Basin Due to Fluid Diffusion Inferred From Seismic and Injection Data Analysis

Source‐Independent Passive Seismic Reverse‐Time Structure Imaging With Grouping Imaging Condition: Method and Application to Microseismic Events Induced by Hydraulic Fracturing

Downhole Microseismic Source Location Based on a Multi‐Dimensional DIRECT Algorithm for Unconventional Oil and Gas Reservoir Exploration

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