The December 2018 ML 5.7 and January 2019 ML 5.3 Earthquakes in South Sichuan Basin Induced by Shale Gas Hydraulic Fracturing

Lei, Xinglin; Wang, Zhiwei; Su, Jinrong

doi:10.1785/0220190029

Cited by 180 publications

(172 citation statements)

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“…We used the generalized cut and paste (gCAP) method (Zhu LP and Ben‐Zion, ), which was advanced in the simultaneous inversion of the full moment tensor and centroid depth using the full waveforms of body and surface waves, to invert the moment tensor of M W > 3.5 earthquakes that occurred in the Shuanghe area. For the Shangluo area, results from a previous study ( Lei XL et al, ) were used; in this study, we applied the same approach and the same velocity model to the Shuanghe area. The original seismograms were typically filtered with corner frequencies of (0.02, 0.15) or (0.02, 0.1).…”

Section: Methodsmentioning

confidence: 99%

“…In the Sichuan Basin of China, both long‐term injections (of durations ranging from a few years to several tens of years) for disposal of wastewater (Lei XL et al, , , Zhang ZW et al, ) and for deep‐well salt mining (Ruan X et al, , Sun XL et al, ), and short‐term injections (of several months’ duration) for shale gas hydraulic fracturing (HF) (Lei XL et al, , , Meng LY et al, ), have caused palpable induced seismicity, resulting in sizable earthquakes up to M 5.7. Similar to other sites (Atkinson et al, ), a high level of HF‐induced seismicity and moderate magnitude earthquakes have been limited to some sites in the Sichuan Basin.…”

Section: Introductionmentioning

confidence: 99%

“…Similar to other sites (Atkinson et al, ), a high level of HF‐induced seismicity and moderate magnitude earthquakes have been limited to some sites in the Sichuan Basin. Among these several injection sites, the long‐term injection into a deep well in the Changning Shuanghe salt mine (Ruan X et al, , Sun XL et al, ) and HF in the Changning Shangluo shale gas block (Lei XL et al, , , Meng LX et al, ) have demonstrated the highest level of induced seismicity (Figures –). Following the M 5.7 Xingwen earthquake on 18 Dec. 2018, which appears to have been induced by HF activities, a magnitude 6.0 earthquake struck a wide region centered on Shuanghe Town, Changning County, late at night on 17 June 2019.…”

Section: Introductionmentioning

confidence: 99%

“…West of the Changning anticline are a number of NE‐extending, parallel, and very long fold zones (see the index map in Figure ). Due to changes in the regional stress field, most faults are unfavorably orientated for rupturing under the present‐day regional stress field (Lei XL et al, ). As a result, the level of background seismic activity in the area is very low.…”

Section: Introductionmentioning

confidence: 99%

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Possible link between long-term and short-term water injections and earthquakes in salt mine and shale gas site in Changning, south Sichuan Basin, China

Lei

Wang

2019

Earth and Planetary Physics

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Late at night on 17 June 2019, a magnitude 6.0 earthquake struck Shuanghe Town and its surrounding area in Changning County, Sichuan, China, becoming the largest earthquake recorded within the southern Sichuan Basin. A series of earthquakes with magnitudes up to 5.6 occurred during a short period after the mainshock, and we thus refer to these earthquakes as the Changning M6 earthquake sequence (or swarm). The mainshock was located very close to a salt mine, into which for ~3 decades fresh water had been extensively injected through several wells at a depth of 2.7–3 km. It was also near (within ~15 km) the epicenter of the 18 December 2018 M5.7 Xingwen earthquake, which is thought to have been induced by shale gas hydraulic fracturing (HF), prompting questions about the possible involvement of industrial activities in the M6 sequence. Following previous studies, this paper focuses on the relationship between injection and seismicity in the Shuanghe salt field and its adjacent Shangluo shale gas block. Except for a period of serious water loss after the start of cross‐well injection in 2005–2006, the frequency of earthquakes shows a slightly increasing tendency. Overall, there is a good correlation between the event rate in the Shuanghe area and the loss of injected water. More than 400 M ≥ 3 earthquakes, including 40 M ≥ 4 and 5 M ≥ 5 events, had been observed by the end of August 2019. Meanwhile, in the Shangluo area, seismicity has increased during drilling and HF operations (mostly in vertical wells) since about 2009, and dramatically since the end of 2014, coincident with the start of systematic HF in the area. The event rate shows a progressively increasing background with some fluctuations, paralleling the increase in HF operations. More than 700 M ≥ 3 earthquakes, including 10 M ≥ 4 and 3 M ≥ 5 in spatially and temporally clustered seismic events, are correlated closely with active fracturing platforms. Well‐resolved centroid moment tensor results for M ≥ 4 earthquakes were shown to occur at very shallow depths around shale formations with active HF, in agreement with some of the clusters, which occurred within the coverage area of temporary or new permanent monitoring stations and thus have been precisely located. After the Xingwen M5.7 earthquake, seismic activity in the salt well area increased significantly. The Xingwen earthquake may have created a unidirectional rupture to the NNW, with an end point close to the NW‐trending fault of the Shuanghe earthquake. Thus, a fault in the Changning anticline might have terminated the fault rupture of the Xingwen earthquake, possibly giving the Xingwen earthquake a role in promoting the Changning M6 event.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Possible link between long-term and short-term water injections and earthquakes in salt mine and shale gas site in Changning, south Sichuan Basin, China

Lei

Wang

2019

Earth and Planetary Physics

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“…For example, the M s 5.7 Wenchuan aftershock in the western Sichuan Basin was located at 3 km depth ; the M s 5.1 Suining-Tongnan earthquake in the center of the Sichuan Basin had a centroid depth of 2 km (Luo et al, 2011); the M L 3.8 Chongqing earthquake in the eastern Sichuan Basin was as shallow as 3 km (Han et al, 2017), and more induced earthquakes with similarly shallow depth (Lei et al, 2019). For example, the M s 5.7 Wenchuan aftershock in the western Sichuan Basin was located at 3 km depth ; the M s 5.1 Suining-Tongnan earthquake in the center of the Sichuan Basin had a centroid depth of 2 km (Luo et al, 2011); the M L 3.8 Chongqing earthquake in the eastern Sichuan Basin was as shallow as 3 km (Han et al, 2017), and more induced earthquakes with similarly shallow depth (Lei et al, 2019).…”

Section: Geophysical Research Lettersmentioning

confidence: 99%

An Extremely Shallow M_w4.1 Thrust Earthquake in the Eastern Sichuan Basin (China) Likely Triggered by Unloading During Infrastructure Construction

Qian

Chen

Luo³

et al. 2019

Geophysical Research Letters

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Triggered or induced earthquakes have been widely reported as resulting from various human activities, yet seismicity triggered by small-scale infrastructure construction is rare. Here, we report on an investigation of an extremely shallow M w 4.1 earthquake which occurred on 11 August 2016 in the Sichuan Basin (China), a region with historically low seismicity. Our seismic waveform analyses indicate an almost pure thrust focal mechanism at a centroid depth of~1 km. Furthermore, 18 Sentinel-1 synthetic aperture radar interferograms, stacked to obtain subcentimeter accuracy, reveal up to 3 cm line-of-sight deformation which overlaps with an automotive testing site constructed in 2014. Removal of 10 m of a surface rock layer during the construction may have produced an unloading effect and resulted in up to 0.11 MPa Coulomb stress changes on a blind fault, larger than the 0.01 MPa threshold typically invoked in studies of tectonic earthquakes. However, the delayed triggering still requires further investigation. Plain Language SummaryWhile induced earthquakes in the shallow part of the crust have been observed globally, a remaining knowledge gap is whether small-scale infrastructure construction can trigger earthquakes or not. We investigate these questions on an extremely shallow M w 4.1 earthquake in the eastern Sichuan Basin (China). To determine earthquake source parameters, we combine seismological data with satellite imaging. We find this thrust event ruptured at the depth of~1 km, located just beneath an automotive testing site constructed in 2014. Crucially, we note the testing site construction involved removal of a large volume of surface rock. We further analyze the stress changes produced by the unloading of the surface rock. We find a possible triggering relationship between the infrastructure construction and the occurrence of this shallow earthquake. Our results thus shed new light on the causes of shallow earthquakes associated with small-scale infrastructure construction.

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Frictional stability of Longmaxi shale gouges and its implication for deep seismic potential in the southeastern Sichuan Basin

Zhang

Cui

et al. 2022

Deep Underground Science and Engineering

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Microearthquakes accompanying shale gas recovery highlight the importance of exploring the frictional and stability properties of shale gouges. Aiming to reveal the influencing factors on fault stability, this paper explores the impact of mineral compositions, effective stress and temperature on the frictional stability of Longmaxi shale gouges in deep reservoirs located in the Luzhou area, southeastern Sichuan Basin. Eleven shear experiments were conducted to define the frictional strength and stability of five shale gouges. The specific experimental conditions were as follows: temperatures: 90-270°C; a confining stress: 95 MPa; and pore fluid pressures: 25-55 MPa. The results show that all five shale gouges generally display high frictional strength with friction coefficients ranging from 0.60 to 0.70 at the aforementioned experiment condition of pressures, and temperatures. Frictional stability is significantly affected by temperature and mineral compositions, but is insensitive to variation in pore fluid pressures. Fault instability is enhanced at higher temperatures (especially at >200°C) and with higher tectosilicate/carbonate contents. The results demonstrate that the combined effect of mineral composition and temperature is particularly important for induced seismicity during hydraulic fracturing in deep shale reservoirs.

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The December 2018 ML 5.7 and January 2019 ML 5.3 Earthquakes in South Sichuan Basin Induced by Shale Gas Hydraulic Fracturing

Cited by 180 publications

References 27 publications

Possible link between long-term and short-term water injections and earthquakes in salt mine and shale gas site in Changning, south Sichuan Basin, China

Possible link between long-term and short-term water injections and earthquakes in salt mine and shale gas site in Changning, south Sichuan Basin, China

An Extremely Shallow M_w4.1 Thrust Earthquake in the Eastern Sichuan Basin (China) Likely Triggered by Unloading During Infrastructure Construction

Frictional stability of Longmaxi shale gouges and its implication for deep seismic potential in the southeastern Sichuan Basin

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The December 2018 ML 5.7 and January 2019 ML 5.3 Earthquakes in South Sichuan Basin Induced by Shale Gas Hydraulic Fracturing

Cited by 180 publications

References 27 publications

Possible link between long-term and short-term water injections and earthquakes in salt mine and shale gas site in Changning, south Sichuan Basin, China

Possible link between long-term and short-term water injections and earthquakes in salt mine and shale gas site in Changning, south Sichuan Basin, China

An Extremely Shallow Mw4.1 Thrust Earthquake in the Eastern Sichuan Basin (China) Likely Triggered by Unloading During Infrastructure Construction

Frictional stability of Longmaxi shale gouges and its implication for deep seismic potential in the southeastern Sichuan Basin

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An Extremely Shallow M_w4.1 Thrust Earthquake in the Eastern Sichuan Basin (China) Likely Triggered by Unloading During Infrastructure Construction