n recent decades, attracted by the global shale gas revolution, China has been enthusiastically applying the new technology of hydraulic fracturing, also known as fracking, a process that injects high-pressured water, sand and chemicals into underground rock to extract natural gas.
According to the US Energy Information Administration, China holds the most important stock of shale gas resources in the world, or about 15 percent of the global total. A 2018 report on shale gas from the United Nations Conference on Trade and Development (UNCTAD) indicates that shale gas resources in China are higher than the combined shale gas resources of the US and Australia.
Although the Chinese government has set ambitious targets for the sector’s development, production of shale gas is low due to obstacles such as complicated geological conditions, a lack of water in areas of high reserves, high costs and problems with developing fracking technology.
The US has profited from the fracking boom as its exploitable gas reserves are concentrated in more accessible areas, such as the plains of the Midwest or the southern states, and at depths of 1,000-2,000 meters. In China, over half of the technically recoverable shale gas resources are found in much deeper underground rocks at depths of 3,000-4,000 meters in the mountainous southwestern Sichuan basin.
Apart from the high costs needed to extract the gas from regions like Sichuan, another area of concern is whether fracking will cause seismic activity, particularly as areas like Sichuan in western China are geologically unstable and prone to large earthquakes.
“Hydraulic fracturing, which causes micro cracking in underground rocks, will definitely lead to minor seismicity – although this is different from earthquakes caused by natural geological movement,” said Zhao Zhengguang from the School of Earth and Environmental Sciences with the University of Queensland, Australia.
“The magnitude of earthquakes caused by fracking activities is normally below zero degrees, equaling the energy released by firecrackers, for example. So people above ground won’t feel any shaking.”
Yu Gang, a seismic expert on hydraulic fracturing with BGP, which describes itself as a “leading geophysical service company” and is part of the China National Petroleum Cooperation, downplayed the risk of earthquakes caused by fracking. He told NewsChina that the deformation of rocks in the Earth’s crust was nowhere near the same as a naturally occurring earthquake. “According to the large amount of data we collected in Sichuan, we found that micro cracking caused by fracking occurs within 100-200 meters horizontally, and dozens of meters maximum vertically, indicating the small scale of movements of reshaped volume of the Earth’s crust. The shift caused by the micro-cracking is at the millimeter level, while an earthquake equaling magnitude 4.0 on the Richter scale may result in a minimum shift of the Earth’s crust up to dozens of centimeters.”
Fracking takes place in Sichuan at depths of 2,000-3,000 meters, Yu said, but the epicenter of earthquakes in that region, which sits on the edge of the Qinghai-Tibet Plateau, is much deeper.
Yet for years, there has been much concern in North America over earthquakes potentially caused by human activity, including fracking for gas or oil.
In 2016, a paper titled “Fault activation by hydraulic fracturing in western Canada” published in the journal Science found that “earthquakes are tightly clustered in space and time near hydraulic fracturing sites.” Furthermore, patterns of seismicity indicate that “stress changes during operations can activate fault slip to an offset distance of over one kilometer, whereas pressurization by hydraulic fracturing into a fault yields episodic seismicity that can persist for months.” NewsChina tried to contact one of the co-authors of the paper, Bao Xuewei, who was then at the department of geoscience, University of Calgary, in Alberta, Canada, and currently at the School of Earth Sciences, Zhejiang University in Hangzhou. Bao refused an interview request.
Other voices proclaim that there is no strong link between hydraulic fracturing and earthquakes. For example, in an article titled “Induced seismicity and hydraulic fracturing for the recovery of hydrocarbons” published in 2013 in the journal Marine and Petroleum Geology, the authors, through studying a total of 198 possible examples of induced earthquakes since 1929 caused by different factors, including mining, reservoir impoundment and waste disposal, found that “to date, hydraulic fracturing has been a relatively benign mechanism compared to other anthropogenic triggers, probably because of the low volumes of fluid and short pumping times used in hydraulic fracturing operations.”
In Bao’s paper, he stated that “seismicity triggered by hydraulic fracturing appears to be strongly localized.” In western Canada, induced seismicity of a magnitude above 3.0 is associated with only around 0.3 percent of hydraulically fractured wells, the paper said.
Zhao Zhengguang said there are two hydraulic injections during the fracturing process for shale gas exploration. The first is to extract the shale gas, and the second occurs when the used injected water is pumped out and recollected as wastewater and injected back underground. “There are already many published papers on wastewater injection-induced micro-earthquakes in Oklahoma and the results have been admitted by the United States Geological Survey (USGS),” Zhao said.
Yu Gang thinks the conclusion drawn by scientists on the situation in the US or Canada does not apply to China. Most of the nation’s shale gas lies in areas plagued by water shortages on mountains. It is costly to transport water to the mountains, so in China water usage is strictly controlled and recycling is required for use in hydraulic fracturing.
An expert on seismic research who spoke under condition of anonymity told NewsChina that establishing links between shale gas extraction and seismicity required local studies due to the unique rock and geological structures at different locations.
There is much less research on shale gas development in China compared to studies on the issue in North America.
According to the paper “Fault reactivation and earthquakes with magnitudes of up to Mw4.7 induced by shale-gas hydraulic fracturing in Sichuan Basin, China” published in the journal Scientific Report in 2017, evidence suggests that a series of earthquakes with magnitudes of up to 4.7 had been induced by “short-term” (several months at a single well) injections for hydraulic fracturing at depths of 2.3 to three kilometers. Considering the increasing hydraulic fracturing operations in Sichuan, the paper calls for geologists, gas operators, regulators and academic communities to work together to “elucidate the local factors governing the high level of injection-induced seismicity, with the ultimate goal of ensuring that shale gas fracking can be carried out effectively and safely.” Lei Xinglin, lead author of the paper, told media in 2013 that due to lack of transparency in data sharing, it would be hard for researchers to undertake research before there is an earthquake.
The seismic expert also indicated that Chinese researchers don’t have access to the necessary data for research purposes from gas operators. Compared to the big three State players in domestic shale gas exploration – China National Petroleum Corporation (CNPC), China Petroleum and Chemical Corporation (Sinopec) and China National Offshore Oil Corporation (CNOOC), the China Earthquake Administration’s position is weak. The administration is hard pressed to obtain data. NewsChina learned that so far only Chongqing Municipality has set up a coordination scheme with shale gas developers within their jurisdiction in sharing data for research purposes.
Zhao said that in North America, data relating to hydraulic fracturing can be obtained from companies, and scientists can download it from Earthquakes Canada or the USGS. But in China, all the data is held as proprietary information by gas companies, so research institutions or even the government’s own earthquake administration cannot get hold of it.
One industry insider told NewsChina that as personal assets of each gas operator, data is top secret and can only be shared internally or with business partners in China. “To address the causal effects of shale gas exploration and earthquakes, China should set up research projects and require gas operators to share their data with researchers,” said the anonymous insider.
On August 17, 2018, fracking activities triggered a 4.4-magnitude earthquake that struck northeast British Columbia, which was later confirmed by the Canadian province’s energy regulator.
According to regulation of monitoring and prevention measures in British Colombia, “operators must immediately stop drilling if seismic activity exceeds 4.0 magnitude.” Operators can only resume once the Oil and Gas Commission has “approved a mitigation plan that could include reducing drilling volumes or pressure.”
Zhao said that in North America a “traffic light monitoring scheme” is adopted by the oil and gas authorities to monitor and regulate fracking-related seismic activity to mitigate against induced seismicity caused by hydraulic fracturing.
In China, according to an article by Wen Xin from the Sichuan Oil and Natural Gas Development Research Center published in December 2017, at present, there is no designated oil and monitoring organization, and companies implement “self-discipline” while government supervision is merely supplemental.
Due to the lack of professional management policies toward shale gas exploration domestically, many practices in the industry still follow traditional oil and gas operation regulations. But existing regulations on the traditional oil and gas industry are inappropriate for shale gas operations.
Wen Xin stated in her article that: “At the national level, there is no implemented Environmental Impact Assessment (EIA) technical guidance for shale gas development projects, so in practice, EIA institutions follow existing guidance for onshore oil and gas development construction projects, which does not sufficiently reflect the potential environmental risk and the environmental protection measures that should be taken.”
Zhang Dawei, former director of the Mineral Resource Storage Evaluation Center with the Ministry of National Land and Resources (now Ministry of Natural Resources) told NewsChina that the Ministry of Natural Resources (MNR) is planning to set up a national standard for environmental impact assessment for shale gas development.
On March 1, the Strategic Research Center of Oil and Gas Resources under the MNR held its annual work conference, at which it was announced that the first ever index on ecological restrictions within the ecological red lines for oil and gas resource exploration will be published in 2019.