Introduction
Since the founding of the People’s Republic of China 70 years ago, China has made great progress in natural gas exploration and development, and has changed from a gas poor country to the sixth largest gas producing country in the world. The sharp increase in gas reserves and per capita gas reserves is enough to explain China’s process of changing from a gas poor country to a large gas producing country. China’s annual gas production in 1949 was 1117×104 m3[1,2], the annual gas consumption per capita was 0.020 6 m3. The annual gas consumption per capita in 2018 was 1602.7×108 m3[3], and the annual gas consumption per capita was 114.857 6 m3. The annual gas consumption per capita had increased by 5575 times in 70 years. China’s proved geological reserves of natural gas in 1949 were 3.85×108 m3[4], the per capita geological reserves of natural gas were 0.710 7 m3, and the total proved geological reserves of natural gas in 2018 were 167 600.24× 108 m3, the per capita geological reserves of natural gas were 12 011.08 m3, which had increased by 16900 times in 70 years. In 1949, China only discovered Ziliujing, Shiyougou and Shengdengshan gas fields in the Sichuan Basin, and small gas fields such as Jinshui, Zhudong, Niushan and Liuchongxi in Taiwan[5]. In 2018, China discovered 313 gas fields, including 5 shale gas fields, 24 coalbed gas fields and 3 carbon dioxide gas fields. Among them, 72 large gas fields had reserves more than 300×108 m3. The geological reserves of the Sulige and Anyue gas fields are both over 1×1012 m3, and the current annual gas production of these two gas fields are both over 100×108 m3.
In the past 70 years, China has made brilliant achievements in gas production, reserves and number of discovered gas fields, which was mainly attributed to the rapid development of seismic exploration and drilling technology. In 1951, China established the first seismic team, and carried out the first PetroChina seismic exploration[6,7] in the Yanchang mining area of the Ordos Basin. By 2018, China had established 191 petroleum exploration seismic teams. The development of China’s seismic exploration technology can be divided into four stages: (1) Stage of light spot earthquake (1964-1971), using “51” light spot seismograph, recording seismic wave information with light spot photography on sensitive paper. It’s characterized with single point reception, non playback, discovery only anticlinal traps and uplifts, and low efficiency and accuracy. (2) Stage of analog earthquake (1965-1981), using analog tape seismograph. It is mainly used for structural interpretation, trying to identify special lithologic bodies with velocity spectrum data. (3) Stage of digital earthquake (1974-1997), using digital seismograph. At this stage, the technology enjoyed increased coverage times and full digital processing interpretation to expand the application field, and was mainly used for the comprehensive evaluation of structure, petrology and petroliferous properties. (4) Stage of “two wide and one high” (2000 to now), which refers to wide frequency band, wide azimuth and high density. It’s used to increase azimuth seismic information, and to solve the anisotropic problems caused by fractures and stresses, which is applied to the fields from conventional reservoir to unconventional reservoir, such as prediction of source rock quality and engineering quality, optimization deployment and field tracking of horizontal wells. It’s characterized by full digital 3D visualization plus virtual reality, letting you see all that you get.
In 1949, there were only 8 shallow and medium-sized drilling rigs in China[5]. However, in 2018, there were 2719 oil drilling rigs in China, mainly medium and deep drilling rigs, as well as ultra-deep drilling rigs. In recent years, with the help of the ultra-deep drilling with a depth of 6000 m, the Keshen, Dabei and Tazhong-1 large gas fields have been found in the Tarim Basin, and the Yuanba and Longgang large gas fields[8] have been found in the Sichuan Basin, plus, the first deep well in Asia (8 882 m)[9] has been completed in the Tarim Basin. Drilling technology developed from vertical well to horizontal well and acid fracturing operation. The horizontal well technology ensures shale gas production and enables the development of the Fuling, Changning and Weiyuan shale gas fields in China.
1. From gas-poor country to gas-rich country
China’s natural gas industry was very poor in the early days of the founding of the People’s Republic of China. After a long and arduous exploration, it has embraced a fast development, making China’s proved reserves of natural gas rise from negligible to the forefront of the world, and its natural gas production rise from negligible to the sixth largest gas producing country in the world.
1.1. The formation of a major country of natural gas resource
In 1949, China’s proved natural gas reserves were only 3.85×108 m3[1]. In the following decades, the growth of natural gas reserves was slow, but it increased significantly in the 40 years after 1979, especially in the late 20 years. From 1949 to 1993, it took 45 years for China’s total proved natural gas reserves to rise to 1×1012 m3 (excluding Taiwan, the same for the following figures), while for the reserves to rise to 2×1012 m3, it took only six years. In 2009, the total proved reserves of natural gas exceeded 7×1012 m3[10], and in 2014, the proved reserves of natural gas exceeded 10×1012 m3. In 2018, the total proved reserves of natural gas exceeded 15×1012 m3 (excluding shale gas, coalbed gas and other unconventional gas) (Fig. 1). It can also be seen from Fig. 1 that the rapid growth of China’s natural gas reserves is closely related to the growth of coal-derived gas reserves, which is the main force of China’s natural gas reserves growth. In 1999, the cumulative proved reserves of coal-derived gas exceeded 1×1012 m3, after only two years, the reserves reached 2×1012 m3, and by 2018, the cumulative reserves exceeded 9×1012 m3.
Fig. 1.
The cumulative proved reserves of natural gas and coal-derived gas in China from 1949 to 2018 and their relationship with large gas fields.
In China, 188 coal-derived gas fields (including 24 coalbed gas fields) were discovered, accounting for 60.1% of 313 gas fields in total. By the end of 2018, the total proved reserves of coal-derived gas fields in China were 92 556×108 m3, accounting for 61.4% of the total proved reserves of gas reservoirs (150 622.6×108 m3) in China in that year, which is consistent with the conclusion that the number of gas fields and proved reserves in previous studies in China are mainly coal-derived gas[11,12,13,14,15,16,17,18].
1.2. The formation of a major country in natural gas production
In 1949, China’s natural gas production was only 1117×104 m3[1,2], and up to 1957, China’s annual natural gas production was less than 1×108 m3; in 1958, the annual gas production reached 1.064 3×108 m3, and in 1976, the annual production of natural gas exceeded 10 billion cubic meters (100.9501×108 m3). In 1998, the annual production of gas was 222.8×108 m3, and the gas consumption per capita was only 17.9 m3, which indicates China as a country poor in natural gas. The standard of a major gas producing country is a country with an annual gas production of 500×108 m3 or more[19]. In 1929, the United States produced 541×108 m3 of gas, which made it the first major country in producing natural gas; in 1960, Russia (former Soviet Union) produced 452.8×108 m3 of gas, becoming the second major country of natural gas production. From 1929 to 2003, there were only 11 major gas producing countries with an annual production of 500×108 m3 or more. Based on analysis, two basic conditions were found for a country to become a major gas producing country: (1) the recoverable resource of natural gas is more than 13×1012 m3; (2) the minimum remaining recoverable reserves are 1.246 2×1012 m3[19]. In 2003, China’s recoverable natural gas resources were 13.32×1012-17×1012 m3, and the remaining recoverable reserves were 2.089 4×1012 m3. Based on this data, Dai Jinxing[19,20], Jia Wenrui[21], Zhang Kang[22] and Zhao Xianzheng[23] concluded that China could become a major gas producing country in 2005. As expected, in 2005, China’s annual gas production was 499.5×108 m3 (including 261.16× 108 m3 of coal-derived gas, accounting for 52.3% of the total production), becoming the 11th major gas producing country in the world (Fig. 2), and there were 12 major gas producing countries in the world. According to Fig. 2, it can be seen that: (1) before becoming a major gas producing country in 2005, the proportion of coal-derived gas production in China’s natural gas in each year was lower than 50% or even lower; after 2005, the proportion of coal-derived gas production in each year was higher than 50%, with an average annual rate of 56.5%, of which the largest proportion was 66.2% in 2008; (2) after 2005, the annual gas growth rate increased.
From 1949 to 2010, after 61 years, China’s cumulative gas production reached 1×1012 m3 (1.017×1012 m3), and then after 8 years from 2010 to 2018, the cumulative production increased to 2×1012 m3 (2.068×1012 m3), which shows that China’s annual gas production has been increasing.
Fig. 2.
Annual production of natural gas (including coal-derived gas) in China from 1949 to 2018.
2. Exploration and development of large gas fields is the main way to the rapid development of natural gas industry
2.1. Large gas fields are the backbone of natural gas industry
By the end of 2018, 72 large gas fields (including 4 shale gas fields and 4 coalbed gas fields) had been discovered in China. The first large gas field in China, Wolonghe Gas Field, was discovered in 1959, with geological reserves of 380×108 m3[19]. The distribution of China’s large gas fields is shown in Fig. 3. It can be seen from Fig. 3 that China’s large gas fields are mainly distributed in three basins: 25 (4 shale gas fields) in Sichuan Basin, 13 (1 coalbed gas field) in Ordos Basin and 10 in Tarim Basin. Meanwhile, these three basins are also China’s main gas producing areas[24]. In 2018, the natural gas production of large gas fields in Ordos Basin was 408.69×108 m3, that of Sichuan Basin is 399.15×108 m3, and that of Tarim Basin was 231.42×108 m3, with production of large gas fields accounting for 87.9%, 92.9% and 85.4% of the total production of each basin respectively. The total production of these three basins is 1 039.26×108 m3, accounting for 65% of China’s total natural gas production. Therefore, these three basins play a dominant role in China's natural gas production.
Super large gas fields with reserves more than 1×1012 m3 are playing significant roles in large gas producing countries. The Sulige and Anyue gas fields in China are both super large gas fields, with annual gas production of over 100×108 m3 with a total gas production of 302.8×108 m3 in 2018, accounting for 18.9% of the total national gas production. Presently, both Russia and the Netherlands, the two largest gas producing countries in the world, are exploring and developing large gas fields to help them change from gas poor countries to large gas producing countries. In 1958, the recoverable reserves of natural gas in the Netherlands were less than 740×108 m3, and the annual production of natural gas was only 2×108 m3. However, in 1959, Groningen super-large gas field with a recoverable reserve of nearly 3×1012 m3 was discovered, and the annual production of natural gas reached 828.8×108 m3 in 1975. Therefore, the Netherlands exported natural gas to Germany, France and Belgium, becoming a large gas producing country[19]. In the early 1950s, Russia (the former Soviet Union) was a gas poor country with natural gas reserves of less than 2 230×108 m3 and annual gas production of only 57×108 m3. From 1960 to 1990, with the discovery of more than 40 large gas fields, the reserves of natural gas reached 453 069×108 m3, and the annual gas production increased from 453×108 m3 to 8 150×108 m3, making it the largest country in natural gas in the world at that time[19].
Fig. 3.
Distribution of large gas fields in China.
2.2. The peak period of large gas field discovery is also a period of rapid growth of reserves and production in China
In 1949, China’s total proved natural gas geological reserves and annual gas production were extremely low. Until 1990, China’s total proved natural gas reserves were only 7 045×108 m3, with an annual production of 152×108 m3. In that 40 years (1949-1990), China’s natural gas reserves and production increased slowly. The main reason is that the number of large gas fields discovered during this period was very small, and only six large gas fields were discovered in China[25], and none of them was found to have reserves over 1 000×108 m3[26] . However, from 1991 to 2018, over 28 years, 2.4 large gas fields on average were discovered every year, and the reserves of a single large gas field were also large, with 33 large gas fields exceeding 10 000×108 m3, and the reserves of the Sulige and Anyue gas fields exceeding 10 000×108 m3. The discovery of these large gas fields enhanced the rapid growth of China’s natural gas reserves and production (Fig. 1). By the end of 2018, the total proved natural gas geological reserves of 72 large gas fields in China reached 124 504×108 m3, accounting for 75% of the national proved natural gas reserves of 16.7×1012 m3.
Based on comparison of Fig. 1 and Fig. 2, it can be seen that from 1991 to 2000, there is a significant positive correlation between the number of discovered gas fields and the growth rate of natural gas reserves, but the positive correlation between the number of discovered gas fields and the annual production growth rate of natural gas in the same period is not significant. This is because of the time needed for the development of the gas field and the construction of the transportation pipeline. This lag has subsided since 2001, and the data shows a significant positive correlation between the discovery rate of large gas fields and the gas reserve and production.
2.3. Research on the main controlling factors and forming conditions for large gas fields accelerates the discovery of large gas fields
Since the “sixth five year plan” period, with the help of national natural gas science and technology research projects, Chinese scholars have continued to carry out research on the main controlling factors of the formation of large gas fields[27,28,29,30,31,32,33,34], and summed up seven quantitative and semi quantitative main controlling factors of the formation of large gas fields[32], and predicted the favorable exploration fields of China’s gas fields, which accelerated the discovery of a large number of large gas fields. The quantitative and semi quantitative main controlling factors for the formation of large gas fields are summarized as follows[32]: (1) The zone with gas intensity greater than 20×108 m3/km2 in the gas center and its periphery is favorable for the formation of the gas field. (2) The gas field is formed late, mainly in the Cenozoic era, if it is formed many times, it then refers to the last formation period. (3) There are paleouplift traps in the effective gas source area. (4) The large gas fields are mostly formed in coal measures or in traps above or below. (5) In the gas area of the large gas field, pore reservoirs are dominating reservoirs. (6) The low gas potential area is favorable for the accumulation of large gas fields. (7) Outside (between) or inside the abnormal pressure storage box, it is favorable for the formation of large gas fields. Based on the above listed research results on the main controlling factors for the formation of the large gas field, the distribution of the large gas field in China is predicted in advance, which provides a theoretical basis for the discovery and exploration of the large gas field in China and accelerates the exploration and development of the large gas field. Fig. 4 is a comparison of the natural gas favorable area or gas accumulation zone in Ordos Basin predicted by natural gas research project since the “sixth five year plan” and the proved large gas fields in different periods later on. The early research results successfully predicted favorable natural gas areas in the Ordos Basin. By the end of 2018, 12 large gas fields (excluding coalbed gas fields) have been found in the Ordos Basin, with proved geological reserves of 43 461.89× 108 m3/km2, including 9 large gas fields of more than 100 billion cubic meters. These gas fields are distributed in the range of favorable natural gas exploration areas predicted in the early stage, and basically located in the gas generating zones where the gas intensity is more than 20×108 m3/km2. The gas generation intensity controls the distribution of the large gas fields.
Fig. 4.
Proved large gas fields in Ordos Basin at different times.
3. New theory of natural gas enhances faster development of natural gas industry
Different natural gas theories can be divided according to different classification principles. As per organic genesis and inorganic genesis of natural gas atoms, there formed the theories of organic genesis and inorganic genesis of natural gas; as per whether the alkane gas comes from sapropelic kerogen or humic kerogen, there formed the theories of oil-associated gas and coal-derived gas; as per the separation or community of reservoir sources, there formed conventional natural gas theory and unconventional natural gas theory, and the latter also includes reservoir source separation such as tight sandstone gas.
Oil-associated gas theory and coal-derived gas theory are meritorious theories that have guided the development of natural gas industry. Promoted by the “shale gas revolution”, unconventional gas theory shows great potential in guiding the natural gas industry for better development in the future.
3.1. The coal-derived gas theory enables China to develop from a gas poor country to a major gas producing country
In the 1870s, the theory of marine oil generation began to sprout in the world, and has been developing and improving since then; in the 1920s, the theory of terrestrial oil generation began to form attributed to Chinese scholars’ efforts[35,36]. Both marine and terrestrial oil generation theories admit that sapropelic shale and carbonate rock are the source rocks of oil and gas. The difference in between is that for the former the source rocks are marine facies, while for the latter the source rocks belong to terrestrial facies. Therefore, both theories can be identified as oil-gas theory. It can be seen that the earliest traditional theory guiding natural gas exploration in the world is oil-associated gas theory.
In the 1940s, German scholars proposed that coal measures can form abundant natural gas, and can accumulate into industrial gas fields[37], but they did not pay attention to whether coal measures can form oil and established a simple coal to gas theory. The emergence of this new theory and itsguidance for natural gas exploration in Western Europe have achieved great success: a large number of coal-derived gas fields such as Groningen super large gas field have been found in the Northwest basin of Germany[17], and at least 455 coal-derived gas fields have been found in the England-Netherland basin[38].
China’s modern petroleum industry started in 1878 and has been guided by the theory of oil-associated gas, i.e. “monism”, for 100 years till 1978[19]. The natural gas industry was extremely weak, and the reserves and production of natural gas were very small. The research on coal-derived gas in China began in the late 1970s. In 1979, the article “Petroleum and Natural Gas Generation during Coalification”[39] pointed out the primary and secondary relationship for gas and oil formed by coal measures, stating that coal measures were the source rocks, while the hydrocarbon generation of coal measures were dominated by gas and supplemented by oil[17, 40]. The emergence of the new theory of coal-derived gas made China's natural gas exploration theory develop from “monism” of oil-associated gas to a “dualism” theory of both coal- derived gas and oil-associated gas. The coal-derived gas theory has opened up a new field for China’s natural gas exploration and promoted the fast development of China’s natural gas industry. It can be seen from the following aspects: (1) Coal-derived gas has promoted China to become a major gas producer, and China became the 11th largest gas producer in the world in 2005. As is well known, reserves are the basis of production. Only when the reserves and production of coal-derived gas exceed 50% of total natural gas, can China become a major producer of natural gas. In 2005, the above two proportions were 62.4% and 52.3% respectively, which indicates that the reserves and production of coal-derived gas are the basis for China to become a major producer of natural gas in the world. (2) Coal-derived gas fields are the backbone of major gas producing countries. By the end of 2018, China had discovered 64 conventional gas fields (with a total proved natural gas reserves of 109 425.21×108 m3, excluding 4 shale gas fields and 4 coalbed methane gas fields), including 45 large coal-derived gas fields, with total proved natural gas reserves of 82 912.42×108 m3. The national total proved natural gas reserves were 167 600.24×108 m3 in China. Therefore, the reserves of coal-derived gas field accounted for 49.47% of national natural gas reserve and 75.77% of total reserve of large gas field. In 2018, the national natural gas production was 1 602.7×108 m3, and the large gas field production was 1 081.56×108 m3, among which the production of coal-derived gas fields was 816.27×108 m3, so the production of coal-derived gas field accounts for 50.93% and 75.47% of the national gas production and the large gas field gas production respectively. (3) The new theory of coal-derived gas guides the exploration and development of natural gas and helps to build the largest gas producing areas in China. The Ordos Basin is the first oil field in China to use modern drilling rigs to explore oil and gas. From well Yan-1 in 1907 to the end of the 1970s, it had been guided by the theory of marine and terrestrial oil generation. The coal-bearing strata of Carboniferous to Permian were not regarded as gas source rocks, and there was no progress in natural gas exploration. At the beginning of 1980, especially the launch of the “Sixth Five Year Plan” and “Coal-derived Gas Development and Research” natural gas scientific and technological research projects, Changqing oil field and many scholars[41,42,43,44,45,46] pointed out that Carboniferous-Permian coal series were good source rocks for natural gas, which is still an important target for natural gas exploration in Changqing oil field. Great progress has been made in Ordos Basin in natural gas exploration and development, making it the first large gas producing area in China. Its annual gas production in 2018 was 464.96×108 m3, which was the first basin with annual gas production exceeding 400×108 m3 in China, accounting for 29% of the total national gas production. The Sulige gas field, a gas field with the highest reserves and production in China, has a proved natural gas reserves of 18 598×108 m3 and an annual gas production of 188.68×108 m3 in 2018, accounting for 11.77% of the national gas production. 12 large gas fields had been found in the whole basin (Fig. 4). Except for the Jingbian gas field, which has mixed source of coal-derived gas and oil-associated gas, all others are coal-derived gas fields, 9 of which have reserves exceeding 1000×108 m3. The Ordos large gas producing area plays an important role in improving environmental pollution in Beijing-Tianjin-Hebei and the eastern part of Northwest China. (4) The discovery and development of coal-derived gas field Kela 2 gave birth to the construction of the West-to-East natural gas transmission project pipelines and the Tarim gas area, the third large gas producing area in China. Although at that time there was an opinion holding that the annual natural gas transmission of the West-to-East natural gas transmission project pipelines was 120×108 m3, the reserve guarantee of Tarim Basin was not enough, and the reserve production ratio was only 28, which was not suitable for the construction of the pipeline; there was another opinion contending that the project could be built[46], because there was the “three most” Kela 2 Gas Field as the basis for the geological and development advantages of natural gas: the largest reserve abundance (59.05×108 m3/km2), the highest gas column height (468 m) and the largest single well (Kela 2-7 well) yield (495.6×104 m3/d). At the same time, Kuqa depression has great potential in coal-derived gas, and more reserves can be found. Later, a number of large coal-derived gas fields were discovered in Dina 2, Dabei and Keshen, which made the reserves for the West-to-East natural gas transport project more sufficient. In addition, Tarim Basin has now become the third large gas producing area in China, which proves that coal-derived gas theory is of great significance to the development of China’s natural gas industry.
3.2. The shale gas theory adds new driving force to the faster development of China’s natural gas industry
Shale gas is a kind of source-reservoir integration natural gas produced from a dark and organic rich shale formation system with very low porosity and permeability, which is mainly accumulated in adsorption or free state, and is essentially a continuously generated biogenic gas, thermogenic gas or a mixture of both[47,48,49]. Shale gas, with its wide distribution and large reserves, had risen rapidly in the past decade and attracted attention of more and more countries. Since the drilling of the first shale gas well with a depth of only 8 m in 1821, it took the United States nearly 200 years to develop the technology, which can mainly be divided into four stages[50]: the first stage (1821-1978), the stage of accidental discovery; the second stage (1978-2003), the stage of understanding innovation and technological breakthrough; the third stage (2003-2006), the stage of horizontal well and hydraulic fracturing technology promotion and application (the stage of great development); the fourth stage (from 2007 till now), the stage of globalization. The United States is the only country in the world to achieve large-scale commercial exploitation of shale gas. In 1981, George Michel, known as the father of Barnett shale gas, realized large-scale fracturing of shale section of well C.W.Slay No.1, which made Barnett shale the first large-scale commercial shale gas field in the United States. This trigged the vigorous development and major breakthrough of shale gas exploration and development in the United States, and set off an upsurge of shale gas exploration and development in the world[51]. At present, great development has been achieved in the United States, China, Canada and Argentina (Fig. 5). In 2018, the shale gas production of the United States was 6072 ×108 m3[52], and the proved shale gas reserves accounted for 66% of the total proved natural gas reserves[53], making the United States change from a major gas producing country that imports natural gas to a major gas producing country that exports natural gas.
Fig. 5.
Production of shale gas from countries in 2018 in the world[52].
Marine shale is widely developed in China and North America, while transitional facies and continental shale are also developed in China. The types of marine shale organic matter in China and North America are mainly type I or typeⅡ1[54]. The marine shale in China is old and deeply buried (1500-5000 m), with high thermal maturity (Ro value is 2.0%-3.5%). The reservoir formation conditions are complex, and it has experienced multiple stages of structural movement, with poor preservation conditions and high exploration risk. The burial depth of continental shale in China is big, but its thermal maturity is low (Ro value is 0.4%-1.3%)[55]. There are a lot of brittle minerals in shale reservoirs in China, with a brittleness coefficient of 46.15%[56]. The brittleness coefficient of North America is 38.27%[57]. In general, as per brittleness, the shales in China are better than those of the USA.
Compared with American shale, Chinese shale has poor preservation conditions due to its deep burial, multi-stage tectonic movement. The marine shale is old and its maturity is high; while the continental shale is new and its maturity is low and most of them are in the stage of oil generation window. The geological conditions of shale gas in China are worse than those in the United States. In 1980, the United States launched the theoretical and technological research project of shale gas development, while China was about 30 years late. Shale gas exploration and development in China has roughly gone through three stages[58]: (1) Stage of learning (2003- 2008); (2) Stage of evaluation of selected area and implementation of well exploration (2009-2012); (3) Stage of large scale construction and production (2013-present). In 2008, with international cooperation, China completed the first shale gas well, Changxin-1. In 2009, PetroChina implemented shale gas vertical well Wei-201. In 2010, two sets of shale gas target intervals, Wufeng-Longmaxi and Qiongzhusi formations were discovered, and industrial shale gas flow was obtained. As a result, since 2013, Fuling, Weiyuan, Changning, Qirong and other shale gas fields have been discovered and developed successively in the south of Sichuan Basin. By the end of 2018, the total proved geological reserves of shale gas in China were 10 455.67×108 m3, including economic recoverable reserves of 313.29×108 m3, and cumulative gas production was 335.24×108 m3. As the geological resources of shale gas in China are (83.3-166.0)× 1012 m3, and the technical recoverable resources are (10.0-36.1)×1012 m3, China has abundant shale gas resources in general, which has a good development prospect[59]. At present, China has become the second largest shale gas producer in the world, and shale gas is also a new driving force for the development of China’s natural gas industry.
3.3. Coalbed methane
There are 74 countries with CBM resources in the world, 90% of which are distributed in 12 major coal producing countries. Countries with relatively early development of coalbed methane industry include the United States, Russia, Germany, Australia, Britain, India, etc., among which the United States is the country with the most successful coalbed methane development and the largest production[60]. The development of coalbed methane resources in China can be divided into three stages: the stage of mine drainage (1952- 1989), the stage of coalbed methane development technology introduction (1989-1995) and the stage of coalbed methane industry formation (1996 to present)[61]. Since 1995, China has established the national coalbed methane development and utilization engineering research center and coal mine gas control research center. In 1997, the first coalbed methane well was drilled in Zaoyuan, Qinnan. By 2015, 10 coalbed methane industry demonstration project bases, including Qinshui, Eastern Ordos and Yangmei, had been built.
China is rich in coalbed methane resources. The results of “a new round of coalbed methane resource evaluation” organized by the Ministry of Land and Resources in 2006 shows that the total geological resources of shallow coalbed methane with a burial depth of 2000 m in China is 36.81×1012 m3, and the recoverable resources are 10.87×1012 m3. According to the results of “dynamic evaluation of coalbed methane resources” organized by the oil and gas strategy research center of the Ministry of Land and Resources in 2015, the total resources of shallow coalbed methane with a burial depth of 2000 m in China is about 30×1012 m3, and the recoverable resources are about 12.5×1012 m3, ranking the third in the world (Table 1). By the end of 2018, the total proved geological reserves of coalbed methane in China were 6521.9×108 m3, the technical recoverable reserves were more than 3253×108 m3, and the economic recoverable reserves were more than 2625×108 m3.
Table 1 Reserve of CBM resources and coal of different countries[62].
| Country | CBM Resources/1012 m3 | Coal Reserve/1012 t |
|---|---|---|
| Russia | 17.0-113.0 | 6.50 |
| Canada | 6.0-76.0 | 7.00 |
| China | 30.0-36.8 | 5.60 |
| USA | 21.0-28.0 | 3.95 |
| Australia | 8.0-14.0 | 1.70 |
China’s coalbed methane resources are geologically characterized by “multiple coal ranks, multiple burial depths, multi-stage gas generation, multi-source superposition and multi-stage transformation”. It is characterized by various types of coal in each coal rank, large span of burial depth, various coal forming conditions, multiple coal forming stages, superposition of coal metamorphism and multiple episodes of structural change, which lead to complex coalbed methane reservoir formation and various types of gas reservoirs[63]. The overall characteristics of CBM occurrence can be summarized as “four lows and one high”, that is, low gas saturation, low permeability, low resource abundance, low reservoir pressure and high metamorphic degree. Compared with the reservoir characteristics of the main producing areas of coalbed methane in the United States, Australia and other countries, China’s coalbed methane reservoir has not only favorable characteristics such as large coal seam thickness, high gas content and moderate burial depth, but also unfavorable factors such as late formation age, complex structure, low pressure coefficient and low permeability[64]. Therefore, China’s coalbed methane development is difficult, and its conditions and production are not as good as that of the United States. In 2018, only 51.5×108 m3 of coalbed methane was produced.
4. Conclusions
In the past 70 years since the founding of the People’s Republic of China, great progress has been made in natural gas exploration and development. China has changed from a gas poor country to the sixth largest gas producing country in the world. In 1949, China’s annual gas production was 1117×104 m3, the proved natural gas reserves were 3.85×108 m3, and the annual domestic gas consumption and reserves per capita were 0.020 6 m3 and 0.710 7 m3 respectively. However, by 2018, the annual domestic gas consumption per capita was 114.857 6 m3, and the natural gas reserves per capita were 12011.08 m3, with domestic gas consumption and reserves per capita increased by 5575 times and 16 900 times respectively.
Exploration and development of large gas field is the main way to rapidly develop the natural gas industry. By the end of 2018, 72 large gas fields had been discovered in China, of which the proved geological reserves of Sulige and Anyue gas fields were more than 1×1012 m3, and the annual gas production was more than 100×108 m3. Large gas fields are mainly distributed in the Sichuan (25), Ordos (13) and Tarim (10) basins. In 2018, the total gas production of the three basins was 1039.26×108 m3, accounting for 65% of China’s total natural gas production. It can be seen that the large gas fields play dominant roles in China’s gas production. By the end of 2018, the total proved natural gas reserves of 72 large gas fields in China were 124 504×108 m3, accounting for 75% of the national proved natural gas reserves of 16.7×1012 m3, which is enough to show that the large gas fields are very important in the natural gas industry.
The new theory of natural gas enhances China’s natural gas industry to develop better and faster. Before 1979, the traditional oil-associated gas theory, i.e. “monism”, guided the exploration of natural gas. Since 1979, coal-derived gas theory has become a new theory to guide the exploration of natural gas. It helped China’s natural gas exploration theory to develop from “monism” to “dualism” (oil-associated gas and coal-derived gas), enabling China’s natural gas industry to develop rapidly. Coal-derived gas is the main gas that made China a major gas producer. In 2018, China’s natural gas production was 1602.7×108 m3, and the gas production of large gas field was 1081.56×108 m3, including 816.27×108 m3 of coal-derived gas field, which accounted for 50.93% and 75.47% of China’s total gas production and large gas field’s gas production respectively; by the end of 2018, China’s total proved reserves of coal-derived gas field were 92 556×108 m3, accounting for 61.4% of the total proved reserves of the year of 150 622.6× 108 m3. Shale gas theory appeared in China at the beginning of the 21st century, but it had made important progress by 2018. At present, the annual production of shale gas is 108.8× 108 m3, and shale gas fields in Fuling, Changning, Weiyuan and Weirong have been explored and developed. The total proved geological reserves of natural gas are 10 455.67×108 m3, and the cumulative production of gas is 335.24×108 m3. Among the four countries (USA, China, Canada, Agentina) that produce shale gas, the production amount of shale gas in China is only second to that of the United States, which shows that shale gas in China has a good prospect.
Reference
Statistical communique of the
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PMID:12264023
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In 1979 China's total industrial and agricultural output value reached 617,500 million yuan, exceeding the economic plan by 1.5%. National income was 337,000 million yuan, which was 7% over 1978. This progress was achieved under the leadership of the Communist Party of China and the people's government through conscientious implementation of the policy of readjustment, restructuring, consolidation, and improvement in the national economy. Discussion of the 1979 economic plan focuses on the following: industry; agriculture; capital construction; transport and post and telecommunications; domestic trade; foreign trade and tourism; science and technology and education and culture; health work and sports; the people's livelihood; and the population. The total 1979 industrial output value was 459,100 million yuan, 0.6% above the plan and 8.5% over 1978. The rate of increase of light industry exceeded that of heavy industry. Plans were met or surpassed for the output of 89 of 100 major products. The total value of agricultural output for 1979 was 158,400 million yuan, 4.2% above the plan and 8.6% higher than the previous year. The fixed assets turned over for use by capital construction units all over China came to 41,800 million yuan, a 17.4% increase over 1978. In 1979 the volume of railway freight transport was 558,800 million ton-kilometers, a 4.8% increase over 1978. The value of commodities purchased by commercial departments totaled 199,240 million yuan, topping 1978 by 14.5%. China had a population of 970.92 million by the end of 1979, 12.83 million people more than the 1978 figure. The birth rate was 17.9/1000 and the death rate was 6.2/1000. China's natural population growth rate was 11.7/1000.
Natural gas geology accelerated the growth of natural gas reserve in large scale in China
Significant advancement in natural gas exploration and development in China during the past sixty years
DOI:10.1016/j.foodchem.2019.125957
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PMID:31864191
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The main aim of this work was to characterize the volatile profile of virgin pistachio oils produced from eight cultivars (Aegina, Avdat, Kastel, Kerman, Larnaka, Mateur, Napoletana and Sirora), under different technological conditions (temperature, roasting, use of whole nuts, screw speed and nozzle diameter), and compare it with those of commercial pistachio oils. Terpenes (15.57-41.05 mg/kg), accounting for ~97% of total volatiles, were associated with appreciated sensory properties, with α-pinene as the main volatile (14.47-37.09 mg/kg). Other terpene compounds such as limonene (0.11-3.58 mg/kg), terpinolene (0.00-1.61 mg/kg), β-pinene (0.12-1.20 mg/kg) and α-terpineol (0.00-1.17 mg/kg) were quantified at lower concentrations. Acids, alcohols, aldehydes, esters and hydrocarbons only summed to ~3% of the total volatile compounds. The volatiles content greatly depended on the pistachio cultivar employed. The influence of extraction conditions was also very relevant; in particular, terpenes doubled (28.38-53.84 mg/kg) using whole pistachios for oil extraction, also being incremented by mild processing conditions. On the contrary, higher temperature or roasting decreased the terpene content (~50-25% respectively), and pyrazines appeared (up to 3.12 mg/kg).
Notes on the early development history of geophysical exploration in petroleum industry (1939-1952)
50 years of technical progress in land petroleum seismic exploration
Based on some accumulated data working in former Ministry of Petroleum Industry，the author briefly reviewed development history of land seismic crew belonging in Chinese petroleum industry (former Ministry of Fuel Industry，Ministry of Petroleum and Chemical Industry，Ministry of Petroleum Industry and today's CNPC )，and development history of amount of works，crew types and field equipment in 50 years after liberation. Under the correct decision of a leading body at a higher level and after the effects of geophysists of several generations，some complete sets of seismic survey technologies having a Chinese land feature have been formed;seismic data processing grew out of nothing， processing level improved steadily;interpretation developed from working by hand to digitized interpretation and from an single structural interpretation to an integrated interpretation (including structural，stratigraphic and lithologic) and a reservoir description;seismic dato processing software and seismic data interpretation software having an independent copyrights have been developed in seismic prospecting softwares. Learning advanced management experiences in production management，the Chinese seismic crew have stepped out of state and gone to world，there are footmarks left by Chinese seismic prospector in Asia Europe，American and Latin American.
Geochemical characteristics of ultra-deep natural gas in the Sichuan Basin, SW China
The first deep well on land in Asia was born in Tarim
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Major developments of coal-formed gas exploration in the last 30 years in China
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DOI:10.1016/S1876-3804(09)60125-7
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Abstract
Since its formation in China 30 years ago, the theory of coal-derived gas has not only opened a new field of coal-derived gas exploration, but also increased the proved reserves of coal-derived gas from 1/10 to 7/10 in the total gas of China; the nation's proved gas reserves rise sharply from 2 264×108 m3 to 6.4×1012 m3; the annual production of gas rises from 137.34×108 m3 to 760×108 m3; and the nation's coal-derived gas fields (reservoirs) increases from less than 10 (excluding Taiwan) to 124. After briefing the major developments of China's coal-derived gas exploration, this paper concentrates on the exploration development of coal-derived gas in Ordos Basin, Tarim Basin and Sichuan Basin where large numbers of coal-derived gas fields have been discovered. With carbon isotopic data of alkane gases, it also demonstrates that some gas fields of controversial origin (Jingbian, Kekeya and Akemomu gas fields) are of, or predominantly of, coal-derived gas, and that a few gas reservoirs (Wolonghe, Naxi, Hejiang gas fields) in the Xujiahe Formation coals of Sichuan Basin are oil-associated gas.
The controlling factors of oil and gas from coal in the Kuqa Depression of Tarim Basin, China
DOI:10.1016/j.coal.2006.04.011 URL [Cited within: 1]
Formation mechanism of tight coal-derived-gas reservoirs with medium-low abundance in T3x Formation
DOI:10.1016/j.marpetgeo.2017.06.032 URL [Cited within: 1]
Geochemical evidence for in situ accumulation of tight gas in the Xujiahe Formation coal measures in the central Sichuan Basin, China
DOI:10.1016/j.coal.2018.07.009 URL [Cited within: 1]
Carbon isotopes of Middle-Lower Jurassic coal-derived alkane gases from the major basins of northwestern China
DOI:10.1016/j.coal.2009.08.007
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Abstract
Coal-derived hydrocarbons from Middle–Lower Jurassic coal-bearing strata in northwestern China are distributed in the Tarim, Junggar, Qaidam, and Turpan-Harmi basins. The former three basins are dominated by coal-derived gas fields, distributed in Cretaceous and Tertiary strata. Turpan-Harmi basin is characterized by coal-derived oil fields which occur in the coal measures. Based on analysis of gas components and carbon isotopic compositions from these basins, three conclusions are drawn in this contribution: 1) Alkane gases with reservoirs of coal measures have no carbon isotopic reversal, whereas alkane gases with reservoirs not of coal measures the extent of carbon isotopic reversal increases with increasing maturity; 2) Coal-derived alkane gases with high δ13C values are found in the Tarim and Qaidam basins (δ13C1: − 19.0 to − 29.9‰; δ13C2: − 18.8 to − 27.1‰), and those with lowest δ13C values occur in the Turpan-Harmi and Junggar basins (δ13C1: − 40.1 to − 44.0‰; δ13C2: − 24.7 to − 27.9‰); and 3) Individual specific carbon isotopic compositions of light hydrocarbons (C5–8) in the coal-derived gases are lower than those in the oil-associated gases. The discovered carbon isotopic reversal of coal-derived gases is caused by isotopic fractionation during migration and secondary alteration. The high and low carbon isotopic values of coal-derived gases in China may have some significance on global natural gas research, especially the low carbon isotope value of methane may provide some information for early thermogenic gases. Coal-derived methane typically has much heavier δ13C than that of oil-associated methane, and this can be used for gas–source rock correlation. The heavy carbon isotope of coal-derived ethane is a common phenomenon in China and it shed lights on the discrimination of gas origin. Since most giant gas fields are of coal-derived origin, comparative studies on coal-derived and oil-associated gases have great significance on future natural gas exploration in the world.
Stable carbon and hydrogen isotopes of natural gases sourced from the Xujiahe Formation in the Sichuan Basin, China
DOI:10.1016/j.orggeochem.2011.10.006
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The compound specific hydrogen and carbon stable isotope ratios of alkanes in natural gases from the Xujiahe and Jurassic formations in the western Sichuan Basin were investigated to distinguish between coal-derived and oil-associated gases. All gases were determined to be coal-derived and sourced from the Xujiahe Formation. Thermal maturities of the source rocks are expected to vary from 0.8-1.8% vitrinite reflectance (%R-o) according to the empirical relationship between the measured delta C-13(CH4) values and % R-o, which is within the scope of the maturities of source rocks (0.7-2.1%). In particular, C1-3 alkanes of primary coal-derived gases which have not undergone any secondary alteration become more enriched in deuterium with increasing molecular mass and the delta D-CH4 values increase with increasing thermal maturity of source rocks. In the Sichuan Basin, delta D values of coal-derived gases sourced from terrigenous source rocks of the Xujiahe Formation are more negative than those of oil-associated gases sourced from marine organic matter of the Sinian, Permian and Triassic formations. (C) 2011 Elsevier Ltd.
Stable carbon isotopes of coal-derived gases sourced from the Mesozoic coal measures in China
DOI:10.1016/j.orggeochem.2014.04.002
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Coal-derived, large scale gas fields derived from the Mesozoic coal measures in China are mainly distributed in the Middle-Lower Jurassic coal measures in the Tarim, Junggar and Turpan-Hami basins in northwest China, and the Upper Triassic Xujiahe Formation coal measure in Sichuan Basin, central China. In 2011, the annual production was 21.6 x 10(9) m(3) and the proved geological reserves were 2485 x 10(9) m(3), accounting for 21% and 30% of the total in China, respectively. Based on analyses of gas composition and stable carbon isotopes ratios of 203 samples and stable carbon isotopes of 102 CO2 samples, the following conclusions were made. (a) Based on diagnostic plots using the stable carbon isotopic and molecular composition of gas samples, alkane gas from the Mesozoic coal measures in China is shown to be coal-derived. (b) According to the delta C-13(2) vs. C2H6 plot of a great number of oil-derived and coal-derived gases in China, it is concluded that gases with delta C-13(2) > -28.5% are coal-derived and those with delta C-13(2) < -28.5% are oil-derived in most cases. (c) Among the natural gases from the Mesozoic coal measures in China, primary coal-derived gases with normal carbon isotopic distribution pattern among the C-1-C-4 alkanes (i.e. delta C-13(1) < delta C-13(2) < delta C-13(3) < delta C-13(4)) are dominant. (d) Carbon isotopic pattern reversal mainly results from the mixing of coal-derived gases having different maturities but the same source and secondly from microbial oxidation of propane (e.g. Mu 3 and Mu 4 wells in the Gumudi gas field, Junggar Basin). (e) CO2 in the coal-derived gases from the Mesozoic coal measures in China has both biogenic and abiogenic origins. The biogenic origin is dominant and the abiogenic CO2 is mainly found in the Kuqa Depression in the Tarim Basin and western Sichuan Basin. (f) Isotopic differences between heavy hydrocarbon gases and methane become less with increasing maturity. (C) 2014 Elsevier Ltd.
The significance of coal-derived gas in major gas producing countries
Origin and migration model of natural gas in L gas field, eastern slope of Yinggehai Sag, China
Chinese great advance: From a gas-shortage country to a giant gas-Producer
Natural gas resources and its prospect in China
DOI:10.3184/003685018X15294876706211
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PMID:30025551
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A review is presented of the manufacture and use of different types of plastic, and the effects of pollution by these materials on animal, human and environmental health, insofar as this is known. Since 2004, the world has made as much plastic as it did in the previous half century, and it has been reckoned that the total mass of virgin plastics ever made amounts to 8.3 billion tonnes, mainly derived from natural gas and crude oil, used as chemical feedstocks and fuel sources. Between 1950 and 2015, a total of 6.3 billion tonnes of primary and secondary (recycled) plastic waste was generated, of which around 9% has been recycled, and 12% incinerated, with the remaining 79% either being stored in landfills or having been released directly into the natural environment. In 2015, 407 million tonnes (Mt) of plastic was produced, of which 164 Mt was consumed by packaging (36% of the total). Although quoted values vary, packaging probably accounts for around one third of all plastics used, of which approximately 40% goes to landfill, while 32% escapes the collection system. It has been deduced that around 9 Mt of plastic entered the oceans in 2010, as a result of mismanaged waste, along with up to 0.5 Mt each of microplastics from washing synthetic textiles, and from the abrasion of tyres on road surfaces. However, the amount of plastics actually measured in the oceans represents less than 1% of the (at least) 150 Mt reckoned to have been released into the oceans over time. Plastic accounts for around 10% by mass of municipal waste, but up to 85% of marine debris items - most of which arrive from land-based sources. Geographically, the five heaviest plastic polluters are P. R. China, Indonesia, Philippines, Vietnam and Sri Lanka, which between them contribute 56% of global plastic waste. Larger, primary plastic items can undergo progressive fragmentation to yield a greater number of increasingly smaller 'secondary' microplastic particles, thus increasing the overall surface area of the plastic material, which enhances its ability to absorb, and concentrate, persistent organic pollutants (POPs) such as dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs), with the potential to transfer them to the tissues of animals that ingest the microplastic particles, particularly in marine environments. Although fears that such microparticles and their toxins may be passed via food webs to humans are not as yet substantiated, the direct ingestion of microplastics by humans via drinking water is a distinct possibility - since 92% of samples taken in the USA and 72% in Europe showed their presence - although any consequent health effects are as yet unclear. Foodstuffs may also become contaminated by microplastics from the air, although any consequent health effects are also unknown. In regard to such airborne sources, it is noteworthy that small plastic particles have been found in human lung tissue, which might prove an adverse health issue under given circumstances. It is also very striking that microplastics have been detected in mountain soils in Switzerland, which are most likely windborne in origin. Arctic ice core samples too have revealed the presence of microplastics, which were most likely carried on ocean currents from the Pacific garbage patch, and from local pollution from shipping and fishing. Thus, sea ice traps large amounts of microplastics and transports them across the Arctic Ocean, but these particles will be released into the global environment when the ice melts, particularly under the influence of a rising mean global temperature. While there is a growing emphasis toward the substitution of petrochemically derived plastics by bioplastics, controversy has arisen in regard to how biodegradable the latter actually are in the open environment, and they presently only account for 0.5% of the total mass of plastics manufactured globally. Since the majority of bioplastics are made from sugar and starch materials, to expand their use significantly raises the prospect of competition between growing crops to supply food or plastics, similarly to the diversion of food crops for the manufacture of primary biofuels. The use of oxo-plastics, which contain additives that assist the material to degrade, is also a matter of concern, since it is claimed that they merely fragment and add to the environmental burden of microplastics; hence, the European Union has moved to restrict their use. Since 6% of the current global oil (including natural gas liquids, NGLs) production is used to manufacture plastic commodities - predicted to rise to 20% by 2050 - the current approaches for the manufacture and use of plastics (including their end-use) demand immediate revision. More extensive collection and recycling of plastic items at the end of their life, for re-use in new production, to offset the use of virgin plastic, is a critical aspect both for reducing the amount of plastic waste entering the environment, and in improving the efficiency of fossil resource use. This is central to the ideology underpinning the circular economy, which has common elements with permaculture, the latter being a regenerative design system based on 'nature as teacher', which could help optimise the use of resources in town and city environments, while minimising and repurposing 'waste'. Thus, food might be produced more on the local than the global scale, with smaller inputs of fuels (including transportation fuels for importing and distributing food), water and fertilisers, and with a marked reduction in the use of plastic packaging. Such an approach, adopted by billions of individuals, could prove of immense significance in ensuring future food security, and in reducing waste and pollution - of all kinds.
Resource potentials and supply-demand trend of natural gas in China
China is rich in natural gas resources but they are unequally distributed over the country with a low degree of exploration and development. The natural gas industry is sitting in a rapid expansion stage with great potentialities and the gas reserves and production will be increased at a high speed in a period of time in the future because of having a clear gas exploration aim. Coalbed methane is an important unconventional gas and its development potentials are considerable. Gas consumption will rise uninterruptedly and the relation between supply and demand is becoming strain day by day. It is predicted that in china a basic balance between supply and demand will be achieved before 2005; the natural gas produced at home will not meet the demands after 2010; and (50～80)×108m3 of gas will be inputted in 2020 . Therefore it is necessary to use the foreign pipeline gas or LNG for meeting the demands on natural gas in China
The four major onshore gas provinces in China
Main controlling factors for the formation of large and medium-sized gas fields in China
Distribution of large-middle sized gas fields in China: Geological characteristics and key controlling factors
Formation conditions and main controlling factors of large gas fields in China
Significances of studies on natural gas geology and geochemistry for natural gas industry in China
DOI:10.1016/S1876-3804(09)60085-9
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[Cited within: 1]
Abstract
In the recent decade, great development has been made in the natural gas industry. By the end of 2007, the total proved geological reserves of natural gas were 6 × 1012 m3. At the same time, the increase rate of annual production has been greater and greater. From the 100 × 108 m3/year in 1976 to 500 × 108 m3/year in 2005, the required time for an increase of 100 × 108 m3 has been 20 years, 5 years, 3 years, and 1 year, respectively. The significance of studies on natural gas geology and geochemistry are: in the 1970s, it was proposed that coal measure be good gas source rocks, and that the coal measure hydrocarbon generation be dominated by gas generation with some oil generation, which opened new opportunity for coal gas exploration and made coal gas increase from 9% to 70% of the total natural gas in China; according to studies on the semi-quantitative and quantitative controlling factors on large gas fields formation and natural gas accumulation zones, 7 out of 11 large gas fields of more than 1 000 × 108 m3 were predicted in advance by 4–11 years; the gas sources of Feixianguan Formation accumulations are various, and the authors expect that there is a coal gas generation center from Longtan Formation in Bazhong, north Sichuan, which is favorable for large coal gas fields.
Some problems in the study of petroleum geology
DOI:10.1016/j.envpol.2017.05.052
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PMID:28624130
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Rapid economic expansion poses serious problems for groundwater resources in arid areas, which typically have high rates of groundwater depletion. In this study, integration of hydrochemical investigations involving chemical and statistical analyses are conducted to assess the factors controlling hydrochemistry and potential pollution in an arid region. Fifty-four groundwater samples were collected from the Dhurma aquifer in Saudi Arabia, and twenty-one physicochemical variables were examined for each sample. Spatial patterns of salinity and nitrate were mapped using fitted variograms. The nitrate spatial distribution shows that nitrate pollution is a persistent problem affecting a wide area of the aquifer. The hydrochemical investigations and cluster analysis reveal four significant clusters of groundwater zones. Five main factors were extracted, which explain &gt;77% of the total data variance. These factors indicated that the chemical characteristics of the groundwater were influenced by rock-water interactions and anthropogenic factors. The identified clusters and factors were validated with hydrochemical investigations. The geogenic factors include the dissolution of various minerals (calcite, aragonite, gypsum, anhydrite, halite and fluorite) and ion exchange processes. The anthropogenic factors include the impact of irrigation return flows and the application of potassium, nitrate, and phosphate fertilizers. Over time, these anthropogenic factors will most likely contribute to further declines in groundwater quality.
A study of methan carbon isotope of coal-formed gas in FRG and its inspiration to us
On the basis of quoting largely the research results of methane carbon isotope of coal-formed gas in FRG, this article summarizes the characteristics of methane carbon isotope of coal-fomred gas in our cou ntry. It is pointed out that the methane carbon isotope is the most reliable indicatiun to distinguish between the coal formed gas and the oil-formed gas. The distribution of coal-fonned gas in coal mine is in two zones: the original zone and the desorption zone. The methane carbon isotope contained in the two zones is obviously different. In the desorption zone, there are three factors which make the methane carbon isotope of coal-formed gas lighter, the desorption diffusion is the main one.
Petroleum and natural gas generation in coalification
Coal-derived gas theory and its discrimination
Preliminary research on natural gas in coal series in China
Estimtion of natural gas resources and reserves in China: With concerning to reserves for West- East gas pipeline project
DOI:10.1016/j.foodchem.2019.125957
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PMID:31864191
[Cited within: 2]
The main aim of this work was to characterize the volatile profile of virgin pistachio oils produced from eight cultivars (Aegina, Avdat, Kastel, Kerman, Larnaka, Mateur, Napoletana and Sirora), under different technological conditions (temperature, roasting, use of whole nuts, screw speed and nozzle diameter), and compare it with those of commercial pistachio oils. Terpenes (15.57-41.05 mg/kg), accounting for ~97% of total volatiles, were associated with appreciated sensory properties, with α-pinene as the main volatile (14.47-37.09 mg/kg). Other terpene compounds such as limonene (0.11-3.58 mg/kg), terpinolene (0.00-1.61 mg/kg), β-pinene (0.12-1.20 mg/kg) and α-terpineol (0.00-1.17 mg/kg) were quantified at lower concentrations. Acids, alcohols, aldehydes, esters and hydrocarbons only summed to ~3% of the total volatile compounds. The volatiles content greatly depended on the pistachio cultivar employed. The influence of extraction conditions was also very relevant; in particular, terpenes doubled (28.38-53.84 mg/kg) using whole pistachios for oil extraction, also being incremented by mild processing conditions. On the contrary, higher temperature or roasting decreased the terpene content (~50-25% respectively), and pyrazines appeared (up to 3.12 mg/kg).
Fractured shale-gas systems
DOI:10.17116/kurort20199605166
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PMID:31626162
[Cited within: 1]
Russia has almost all hydrochemical types of underground mineral waters; however, unlike the well-known and popular resorts in the world, they are used very limitedly. In addition to their high medicinal value, mineral waters, when properly marketed, is a natural product that is comparable, and, in many cases, superior in price to that of similar volumes of high-octane gasoline. In addition to the characteristics of the chemical and gas composition, some underground mineral waters in their native state have an elevated temperature and are thermal and hyperthermal. Low-mineralized nitrogen thermae are one of the large groups of mineral waters; they are common in the areas of young tectonic faults in the earth's crust, which frame the mountainous areas. The deposits of thermae within the blocky and folded-blocky structures are fractured water-pressure systems; the thermal waters in the sedimentary and volcanic-sedimentary rocks saturate the reservoir or fissure-interstitial aquifers and are typical artesian basins. The successful development of health resort business in Russia should be, first of all, based on the extensive use of natural therapeutic factors. As clearly confirmed by the experience with spa treatment in both Russia and world practice, accumulated data from researches, thermal mineral waters determine the possibility of creating large spa centers that provide high economic efficiency.
Shale gas and its reservoir formation mechanism
DOI:10.1002/1520-6696(198110)17:4&lt;466::aid-jhbs2300170403&gt;3.0.co;2-1
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PMID:7040542
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This paper has two related goals. First, it seeks to show that the theory of perception found in William James's Principles of Psychology is thoroughly consistent if it is approached through the framework of perceptual realism versus constructionism rather than the nativism versus empiricism debate. As such, this paper offers an alternative to Nicholas Pastore's claim that there are two contradictory theories of perception in the Principles. James's commitment of perceptual realism is articulated within the contexts of his (1) critique of constructionist perception theories, (2) notion of the spatial quale, and (3) formulation of the role of knowledge in adult perception. The second goal of this paper deals with the historical development of James's perceptual realism. Here it is argued that Shadworth Hodgson's method of reflection-an anticipation of Husserl's phenomenological reduction-served as the basis of James's commitment of perceptual realism.
Resource potential exploration and development prospect of shale gas in the whole world
Shale gas: Analysis of its role in the global energy market
DOI:10.1007/s11356-019-05388-4
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PMID:31115807
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For the last three decades, both China and India are considered as the largest emerging market economies in the world. Both of these economies play an essential role in the global economy in terms of economic output and CO2 emissions. Hence, these countries are expected to play an important role in setting up environmental and sustainable development policies. Therefore, our paper aims to examine the role of natural gas and renewable energy consumptions on CO2 emissions and economic growth during 1965-2016 within a multivariate framework. The autoregressive distributed lag bounds testing approach to cointegration and vector error correction model (VECM) is employed to explore the long-run and causal nexus among the natural gas consumption, renewable energy consumption, coal and petroleum consumption, CO2 emissions, and economic growth, respectively. The empirical results show existence of long-run equilibrium association among the variables. The Granger causality results indicate that the short-run bidirectional causality between renewable energy consumption and economic growth in India, while no causality is found between these two variables in China. However, natural gas consumption causes economic growth in China whereas no causality is confirmed in India in the short-run. The findings further suggest that there is long-run bidirectional causality among the considered variables in both countries. Our paper addresses several important policy implications.
Energy Information Administration
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DOI:10.3389/fimmu.2019.02714
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PMID:31849940
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Coal is one of the most abundant and economic sources for global energy production. However, the burning of coal is widely recognized as a significant contributor to atmospheric particulate matter linked to deleterious respiratory impacts. Recently, we have discovered that burning coal generates large quantities of otherwise rare Magnéli phase titanium suboxides from TiO2 minerals naturally present in coal. These nanoscale Magnéli phases are biologically active without photostimulation and toxic to airway epithelial cells in vitro and to zebrafish in vivo. Here, we sought to determine the clinical and physiological impact of pulmonary exposure to Magnéli phases using mice as mammalian model organisms. Mice were exposed to the most frequently found Magnéli phases, Ti6O11, at 100 parts per million (ppm) via intratracheal administration. Local and systemic titanium concentrations, lung pathology, and changes in airway mechanics were assessed. Additional mechanistic studies were conducted with primary bone marrow derived macrophages. Our results indicate that macrophages are the cell type most impacted by exposure to these nanoscale particles. Following phagocytosis, macrophages fail to properly eliminate Magnéli phases, resulting in increased oxidative stress, mitochondrial dysfunction, and ultimately apoptosis. In the lungs, these nanoparticles become concentrated in macrophages, resulting in a feedback loop of reactive oxygen species production, cell death, and the initiation of gene expression profiles consistent with lung injury within 6 weeks of exposure. Chronic exposure and accumulation of Magnéli phases ultimately results in significantly reduced lung function impacting airway resistance, compliance, and elastance. Together, these studies demonstrate that Magnéli phases are toxic in the mammalian airway and are likely a significant nanoscale environmental pollutant, especially in geographic regions where coal combustion is a major contributor to atmospheric particulate matter.
Energy Information Administration. U.S. crude oil and natural gas proved reserves, year-end 2018. Washington: U.S
Comparison of the formation condition of shale gas between domestic and abroad and favorable areas evaluation
DOI:10.11764/j.issn.1672-1926.2015.05.0986
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[Cited within: 1]
In order to optimize the favorable area and strata of shale gas,we investigate the latest literature about organic-rich shale in basins of America and China.According to the comparison and analysis of the regional tectonic background,organic carbon content,sedimentary environment,organic carbon content,reservoir property,gas content and so on of the shale between North America and China,the following results have been reached:(1)Both China marine shale and America shale have similar organic matter abundance and types(typeⅠor type Ⅱ1).The thermal maturities of China′s marine shale are higher than America′s,which indicate that China′s marine shale have already generated adequate hydrocarbon;TOC(total organic carbon)of terrestrial shale is lower than that of America′s.Their organic type belongs to typeⅡ2 or type Ⅲ and maturity varies from 2% to 4.5%.Those indicate that the potential to generate hydrocarbon of terrestrial shale is lower than that of marine shale.(2)With similar content of clay mineral,China′s marine shale contains more brittle mineral,which is conductive to fracturing|In contrast,terrestrial shale contains less brittle mineral than that of America′s.(3)With similar pore types and porosity,China′s marine shale shows as good quality of reservoir as America′s.But terrestrial shale shows relatively lower porosity compared with the marine shale of America′s.(4)Burial depth of china′s marine shale distributes from 1 200m to 5 300m,which is wider than that of America′s(1 300-4 000m).Meanwhile,due to the much more complicated tectonic evolution than the stable geotectonic background of America′s shale,those factors result in poor preservation condition of China′s marine shale and terrestrial shale.Therefore we propose an evaluation criterion of shale gas that suits for the marine/terrestrial shale in China according to the result of comparison and the exploration practice.An evaluation of favorable area and strata is carried out on the base of the shale gas assessment criterion.The result shows that the optimum strata of marine shale are the O3w-S1l of Chongqing and its adjacent area,the ∈1q and S1l of Weiyuan area.And the optimum strata of continental shale are T3y of Ordos Basin and K1q of Songliao Basin.
Shale gas in China: Characteristics, challenges and prospects(II)
In fluence factors and evaluation methods of the gas shale fracability
Natural fractures in the Barnett Shale and their importance for hydraulic fracture treatments
DOI:10.1306/11010606061 URL [Cited within: 1]
Has China ushered in the shale oil and gas revolution?
DOI:10.1016/j.foodchem.2019.125957
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PMID:31864191
[Cited within: 1]
The main aim of this work was to characterize the volatile profile of virgin pistachio oils produced from eight cultivars (Aegina, Avdat, Kastel, Kerman, Larnaka, Mateur, Napoletana and Sirora), under different technological conditions (temperature, roasting, use of whole nuts, screw speed and nozzle diameter), and compare it with those of commercial pistachio oils. Terpenes (15.57-41.05 mg/kg), accounting for ~97% of total volatiles, were associated with appreciated sensory properties, with α-pinene as the main volatile (14.47-37.09 mg/kg). Other terpene compounds such as limonene (0.11-3.58 mg/kg), terpinolene (0.00-1.61 mg/kg), β-pinene (0.12-1.20 mg/kg) and α-terpineol (0.00-1.17 mg/kg) were quantified at lower concentrations. Acids, alcohols, aldehydes, esters and hydrocarbons only summed to ~3% of the total volatile compounds. The volatiles content greatly depended on the pistachio cultivar employed. The influence of extraction conditions was also very relevant; in particular, terpenes doubled (28.38-53.84 mg/kg) using whole pistachios for oil extraction, also being incremented by mild processing conditions. On the contrary, higher temperature or roasting decreased the terpene content (~50-25% respectively), and pyrazines appeared (up to 3.12 mg/kg).
The inspire of overseas coal-bed methane’s exploitation and utilization
Pondering on CBM geological features and research trend in China
Whether the coal-bed methane can be reversed into the “Chinese shale gas”?
