1. The concept of super basin
The Sichuan Basin is a large superimposed basin developed on the basis of craton, with an area of about 18×104 km2. The world's first gas field, Ziliujing gas field, was found in the basin in the 13th century[1,2]. From 1949 to 2019, the cumulative gas production in the Sichuan Basin was 6487.8 × 108 m3, which is the basin with the largest gas production in China in the same period. The Sichuan Basin has developed sedimentary rocks with a thickness of up to 12 000 m, including 9 sets of source rocks. It has become the basin with the most developed strata of source rocks in China. The Sichuan Basin is rich in natural gas resources, and the remaining recoverable resources of conventional and unconventional natural gas reach 136404×108 m3[3]. The basin contains many oil and gas reservoirs, forming multiple oil and gas layers, including 25 conventional and tight oil and gas producing layers (18 marine facies) and 2 shale gas producing layers. It is the basin with the most industrial oil and gas reservoirs found so far in China[4,5]. The Anyue gas field, the largest gas field in the basin, is also the largest gas field in carbonate reservoirs in China. The geological gas reserves of 11709×108 m3 were proved in 2019, with gas production of 120.13×108 m3 in that year. It is not only the first gas field with an annual output of more than 100×108 m3 in the Sichuan Basin, but also the third gas field with an annual output of more than 100×108 m3 in China. With abundant geological reserves and the development of many large gas fields, the Sichuan Basin has become the second largest gas producing area in China, with an annual gas output of 335×108 m3 in 2019.
The concept of “Super Basin” was first proposed by IHS (information handling services) oil and gas consulting company in 2016[6]. Fryklund and Stark[7] pointed out that there were 49 continental super basins in the world (Fig. 1). The so-called “Super Basin” refers to the cumulative production of more than 50 × 108 BBL oil equivalent (6.82 × 108 t oil or 7 931.66 × 108 m3 of gas), and sedimentary basin with the remaining recoverable resources of more than 50 × 108 BBL oil equivalent. The super basin is mainly characterized by the following five features: (1) The output exceeds 50 × 108 BBL oil equivalent (6.82 × 108 t oil or 7 931.66 × 108 m3 gas); (2) There are often two or more sets of source rocks; (3) Oil and gas system is usually composed of superimposed oil layers; (4) Mature development, such as development with better infrastructure and service industry development, can lead to the downstream market; (5) Contains potential remaining resources of at least 50 × 108 BBL oil equivalent[7]. The basic characteristics of the Sichuan Basin are similar to the five key characteristics of super basins summarized by Fryklund and Stark[7], so it is listed as one of the 49 super basins in the world by Fryklund and Stark[7]. Among the 49 super basins, 25 super basins have cumulative production and remaining recoverable resources exceeding 50 × 108 BBL oil equivalent, which are called the first-tier super basins, such as Songliao Basin and Bohai Bay Basin in China. The remaining 24 basins have slightly less cumulative production or remaining recoverable resources. According to the above standards, they are called second-tier super basins, such as Sichuan Basin, Tarim Basin and Junggar Basin in China[7]. In fact, according to the above criterion of cumulative production and remaining recoverable resources, the Ordos Basin in China can also be listed as a super basin, so the actual number of continental super basins in the world should be 50 at present (Fig. 1).
Fig. 1.
Fig. 1.
Distribution of super basins in the world (Modified and supplemented according to literature [7]).
2. Four advantages of natural gas geology in Sichuan Basin
The Sichuan Basin can become a super gas basin because it has four advantages in natural gas geology: gas source rock, resources, large gas field, and total output.
2.1. The advantage of gas source rock
The number of gas source rocks in the Sichuan Basin ranks first among all basins in China. There are mainly 9 sets of gas source rocks, including Sinian Doushantuo and Dengying formations, Cambrian Qiongzhusi Formation, Ordovician Wufeng-Silurian Longmaxi formations, Permian Qixia, Maokou, Changxing/Dalong, Longtan/Wujiaping formations, and Triassic Xujiahe Formation (Fig. 2). The first 7 sets are mainly source rocks of marine facies. But Longtan/Wujiaping Formation is a set of transitional facies source rocks. The Longtan Formation is a set of coal- measure source rock, similar to Xujiahe Formation, while the Wujiaping Formation is contemporaneous and heteropic with Longtan Formation, and the main body is a set of marine sapropelic source rocks. The Sichuan Basin has the advantage of forming plentiful natural gas resources. The total gas generation amount in the Sichuan Basin is 4286.35 × 1012 m3, of which the gas generation amount of the main gas source rock of the Lower Cambrian Qiongzhusi Formation is 1451.61 × 1012 m3, with the highest gas generation intensity of 360 × 108 m3/km2 in Weiyuan area. The total gas generation amount of gas source rock of Silurian Longmaxi Formation is 819.01 × 1012 m3, with the highest gas intensity of 280 × 108 m3/km2 and 160 × 108 m3/km2 in the Luzhou and Shizhu areas, respectively.
Fig. 2.
Fig. 2.
Comprehensive histogram of source-reservoir-caprock in the Sichuan Basin. T3x-Upper Triassic Xujiahe Formation; T2l-Middle Triassic Leikoupo Formation; T1j-Lower Triassic Jialingjiang Formation; T1f-Lower Triassic Feixianguan Formation; P3ch-Upper Permian Changxing Formation; P2m-Middle Permian Maokou Formation; P2q-Middle Permian Qixia Formation; P1l-Lower Permian Liangshan Formation; C2h-Middle Carboniferous Huanglong Formation.
2.2. The advantage of resources
The Sichuan Basin is rich both in conventional and unconventional natural gas resources. The remaining recoverable resources of conventional natural gas are 59561 × 108 m3, with a total recoverable resource of 73859 × 108 m3. The types of unconventional natural gas include tight sandstone gas, shale gas and coalbed methane. The remaining recoverable resources amount to 76842.86 ×108 m3, with a total recoverable resource of 82 623 × 108 m3. The total remaining recoverable resources in the basin amount to 136 404 × 108 m3, with a total recoverable resource of 156 482 × 108 m3. The remaining recoverable resources (Fig. 3) and total recoverable resources of natural gas in the Sichuan Basin rank the first among all the basins in China, which endorses it with the resource advantages. At the same time, the remaining recoverable resources and total recoverable resources in the Sichuan Basin exceed the oil equivalent index of the world’s super basin[7] (7931.66 × 108 m3 gas). Therefore, Sichuan Basin should be considered as a super gas basin. Norway's total recoverable natural gas resources in 2019 amounted to 7 × 1012 m3, with an annual natural gas output of 1143.9 × 108 m3, becoming the eighth largest gas producer in the world[8]. Presently, the total recoverable natural gas resources in the Sichuan Basin exceed 7 × 1012 m3, so the annual output will exceed 1000 × 108 m3 in the future based on the recoverable resources.
Fig. 3.
Fig. 3.
Comparison of remaining recoverable natural gas resources in Sichuan, Ordos, and Tarim basins in China.
2.3. The advantage of large gas field
Exploration and development of large gas fields is an important way to enhance the rapid development of a country’s natural gas industry. By exploring and developing large gas fields, the Netherlands and Russia (former Soviet Union), the world’s major gas producing countries, have changed 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, with an annual gas output of only 2 × 108 m3. Since the Groningen giant gas field with recoverable reserves of nearly 3 × 1012 m3 was found in 1959, and the annual gas output reached 828.8 × 108 m3 in 1975, the Netherlands thus had become a large gas producer, beginning to export natural gas to Germany, France, and Belgium. In the early 1950s, the natural gas reserves of the Soviet Union were less than 2230 × 108 m3, with an annual gas output of only 57 × 108 m3, being a gas-poor country. From 1960 to 1990, more than 40 large gas fields were discovered, bringing the natural gas reserves to 453 069 × 108 m3, annual natural gas production increasing from 453 × 108 m3 to 8150 × 108 m3, making it the top gas producing country in the world at that time[9]. The slow growth of natural gas reserves and production in China from 1949 to 1990 was mainly due to the very few large gas fields discovered during this period. Only six large gas fields had been proved in China[10], with no large gas field with reserves of more than 1000 × 108 m3[11]. However, during the 29 years from 1991 to 2019, 2.65 large gas fields on average were discovered every year, and the scale of single large gas field also increased. There were 36 large gas fields each with proved reserves of more than 1000 × 108 m3. Among these large gas fields, the Sulige and Anyue large gas fields were found to have reserves exceeding 10000 × 108 m3. By the end of 2019, the total proved geological reserves of natural gas in 74 large gas fields in China had reached 140 035 × 108 m3, and the annual output of large gas fields in that year was 1348 × 108 m3, accounting for 76.5% of both China's total reserves and total annual output. Large gas fields distribute mainly in Sichuan (27) (Fig. 4), Ordos (15), and Tarim (10) basins. The number of large gas fields in the Sichuan Basin ranks the first position among all basins in China, and has the advantage of large gas fields. The Anyue giant gas field in the Sichuan Basin is the first one in China with proved reserves of more than one trillion cubic meters (11 709 × 108 m3) in ancient carbonate rocks (Cambrian Longwangmiao Formation and Sinian Dengying Formation), a giant gas field with an annual output of more than 10 billion cubic meters. At the same time, it is also found that the proved reserves of Fuling, Changning, and Weiyuan shale gas fields are all more than 4000 × 108 m3, with an annual gas output of more than 200 × 108 m3. The Sichuan Basin has obvious national advantages in the number of large gas fields, and in the reserves and quantity of unconventional large gas fields.
Fig. 4.
Fig. 4.
Distribution of large gas fields in the Sichuan Basin.
2.4. The advantage of total output
By the end of 2019, the total proved geological reserves of natural gas in the Sichuan Basin were 57 966 × 108 m3 (Fig. 5), with a cumulative total gas production of 6488 × 108 m3 (Fig. 6), ranking the first among all basins in China. However, by the end of 2019, the cumulative oil production was very low, i.e., 729.6 × 104 t (equivalent gas 84.85 × 108 m3), so its total oil and gas production by the end of 2019 was 6569.24 × 108 m3, with a gas-oil ratio of 80:1, which means it is a natural gas basin with absolute advantages in gas production. According to the standard of the cumulative natural gas production of super basin (7931.66 × 108 m3), the current natural gas production in the Sichuan Basin of 6569.24 × 108 m3 is slightly lower than the standard value, so Fryklund and Stark listed the Sichuan Basin as a second-tier super basin[7]. In general, the remaining recoverable resources in the Sichuan Basin amount to 136 404 × 108 m3, with a total oil and gas production of 6569.24 × 108 m3. According to these two indicators and the gas-oil ratio of 80:1, the Sichuan Basin should be considered as a super gas basin. Liu et al. had declared that "the Sichuan Basin is expected to become a 'super' petroliferous basin"[12].
Fig. 5.
Fig. 5.
Cumulative proved geological reserves of natural gas in China's main gas producing basins by the end of 2019.
Fig. 6.
Fig. 6.
Cumulative natural gas production of major gas producing basins in China by the end of 2019.
3. Four major breakthroughs in natural gas exploration and development in Sichuan Basin
The Sichuan Basin has achieved major breakthroughs in the exploration and development of giant shale gas, tight sandstone gas, carbonate rock gas fields with the gas reserves reaching 1012 m3, and ultra-deep gas reservoirs for the first time in China. It has thus been a leader in China's natural gas exploration and development, and has established four new areas and accelerated the development of China's natural gas industry.
3.1. Major breakthrough in shale gas
The "shale gas revolution" in the United States is a major directional breakthrough in the natural gas exploration and development in the world, which has enabled the United States to change from a natural gas importing country to a gas producing country exporting natural gas[13]. Its shale gas production in 2019 was 7140 × 108 m3[14], accounting for 76.8% of the total gas production of the United States in that year. The major breakthrough in shale gas exploration and development in the United States had a far-reaching impact on the development of the world's natural gas industry. Significant achievements have been made in shale gas exploration and development from Ordovician Wufeng Formation to Silurian Longmaxi Formation in the Sichuan Basin, China: by the end of 2019, the cumulative proved geological reserves of shale gas were 18 099.9 × 108 m3, and the cumulative gas production was 492 × 108 m3. Six shale gas fields of Fuling, Changning, Weiyuan, Taiyang, Weirong, and Yongchuan have been proved, of which the first five shale gas fields have proved geological reserves of more than 1000 × 108 m3. However, no major breakthrough has been made in shale gas exploration in other domestic basins. Therefore, the Sichuan Basin is the first successful example in shale gas exploration and development in China. Many scholars have studied and commented on the directional leading role of shale gas from Wufeng-Longmaxi formations in the development of natural gas industry in the Sichuan Basin and even the whole country[15,16].
Currently, in the world's shale gas producing countries such as the United States, China, Argentina, and Canada, shale gas comes from marine sapropelic shale. In recent years, important discovery of natural gas has also been obtained in the lacustrine shale of Da’anzhai section of Lower Jurassic Ziliujing Formation in Yuanba and Fuling areas of the Sichuan Basin. The organic matter type of shale in Da’anzhai section is Ⅱ2 or Ⅲ, with TOC value of 0.33%- 3.78% and RO value of 1.11%-1.82%. High-yield oil and gas flow, mainly gas production, have been achieved in 12 wells. Among the 9 wells in Yuanba area, 8 are gas wells, with only 1 well being oil and gas co-production (well YB161), and the daily gas production of well YB21 is up to 50.70 × 104 m3[17,18]. This example provides directional enlightenment and great significance for the exploration and development of terrigenous humic shale gas.
3.2. Major breakthrough in tight shale gas
The Zhongba gas field in northwestern Sichuan Basin consists of two main gas reservoirs: (1) the carbonate gas reservoir in member 3 of Middle Triassic Leikoupo Formation, discovered in December 1972, with proved reserves of 86.3 × 108 m3; (2) the sandstone gas reservoir in member 2 of Upper Triassic Xujiahe Formation was discovered in January 1973 with proved reserves of 100× 108 m3. Based on the statistics of 1435 porosity samples from 5 coring wells in member 2 of Xujiahe Formation, the porosity is 0.08%-16.63%, with an average of 6.20%; based on the permeability statistics of 1319 samples, the maximum value is 22.230 × 10-3 μm2, and the minimum value is less than 0.001 × 10-3 μm2, with the average value of 0.080 × 10-3 μm2. It can be seen that the reservoir matrix has poor physical properties and is a tight sandstone reservoir with low porosity and low permeability[19]. It was put into trial production in August 1973. By the end of 2005, the cumulative gas production was 72.81×108 m3, with a recovery rate of 72.81%. The gas reservoir in member 2 of Xujiahe Formation in the Zhongba gas field is the first developed tight sandstone gas reservoir with high recovery not only in the Sichuan Basin, but also in China. It has been a directional enlightenment in the exploration and development of tight sandstone gas. Presently, 1/4 of the national annual gas output is tight sandstone gas, benefited from the successful pilot development of tight sandstone gas reservoirs in member 2 of Xujiahe Formation.
3.3. Major breakthrough in ancient carbonate giant gas fields
The lithologies of the three main reservoirs of the Cambrian Longwangmiao Formation and members 2 and 4 of the Sinian Dengying Formation developed in Anyue gas field are carbonate rocks[20]. According to the sample analysis of the Sinian Cambrian natural gas, source rock, and reservoir bitumen in the gas field, the comprehensive research and comparison of gas-gas, gas-source, and reservoir bitumen-source rock correlations were conducted[21,22,23]. It was concluded that the natural gas of Longwangmiao Formation mainly came from the source rocks of Cambrian Qiongzhusi Formation. Natural gases in members 2 and 4 of Dengying Formation are both oil-cracking gases[20,21,22] and mainly came from the source rocks of Sinian Dengying Formation and Cambrian Qiongzhusi Formation[21]. The discovery and development of Anyue giant carbonate gas field has played a directional leading role in the exploration and development of giant gas field of more than trillion cubic meters in the lower Paleozoic carbonate rocks of Sichuan, Tarim, and Ordos basins[23]. For example, Well Jiaotan 1 on the Moxi North Slope in the paleouplift of central Sichuan produces gas of 51.62×104 m3/d in member 1 of Cambrian Canglangpu Formation, which is another major breakthrough in natural gas exploration after the discovery of Longwangmiao Formation gas reservoirs of Anyue giant gas field[24,25,26,27]. This indicates that Moxi North Slope in the ancient uplift of central Sichuan may be a gas area of trillion cubic meters.
3.4. Major breakthrough in ultra-deep gas reservoirs
Gas reservoirs deeper than 6000 m are regarded as ultra-deep gas reservoirs[4]. The Permian Maokou Formation gas reservoir (7153.5-7175.0 m) in Laoguanmiao gas field is the first ultra-deep gas reservoir discovered in China[4,28]. In the first ten days of June 1978, the open hole test was carried out on the well section 7053.57-7175.00 m in Maokou Formation of Guanji well, and an industrial gas flow of 4.88×104 m3/d was obtained. This provided valuable experience for the subsequent gas testing technology of deep wells and ultra-deep wells[29], and played a directional leading role in the exploration and development of ultra-deep gas reservoirs in the Sichuan Basin and the whole country. At present, the main production layers of Yuanba and Longgang gas fields in the Sichuan Basin, and Keshen and Dabei gas fields in Tarim Basin are ultra-deep gas reservoirs[4,30-32], showing the great potential of ultra-deep gas exploration in China[33].
4. Classification of super basins
Super basins can be classified according to different criteria. According to the total production and remaining recoverable resources of oil and gas for super basin with 50×108 BBL oil equivalent (6.82 × 108 t oil or 7931.66× 108 m3 gas), the basins whose amount is higher than this standard are considered as the first-tier super basins, and the basins slightly less than this standard are considered as the second-tier super basins[7].
According to the geotectonic attributes of super basins, super basins can be classified into five categories: (1) Foreland super basins, typical examples include Western Canada Sedimentary Basin (WCSB) in Alberta and Permian Basin; (2) The intracontinental cratonic super basin, typical examples include West Siberian Basin and Williston Basin; (3) Thrust belt type super basin, with Zagros basin as a typical example; (4) Rift type super basin, with Songliao Basin and Anadako Basin as typical examples; (5) Passive continental margin super basins, typical examples include the Gulf of Mexico Basin and the Niger Delta Basin[12]. With the highest contribution, foreland super basins account for 47% of the cumulative oil and gas production of super basins and 62% of the remaining recoverable oil and gas reserves. The super basins with less cumulative oil and gas production are catonic super basins, passive continental margin super basins, and thrust belt super basins. Rift super basins account for the lowest proportion[12].
According to the percentage of oil and percentage of gas in the total oil and gas production, super basins are classified into three categories in this study (Table 1): (1) Super oil basins, where oil accounts for more than 80% of the total oil and gas production with the percentage of gas less than 20%, examples are Songliao, Bohai Bay, Campos, and Williston basins, of which the oil production of Songliao Basin and Campos Basin accounts for 94.71%; (2) Super oil and gas basins, with oil production of 20%- 80%, most super basins are of this type, with typical examples of Alberta, Permian, and West Siberia basins; (3) Super gas basins, where gas accounts for more than 80% of the total oil and gas production, while oil accounts for less than 20%. The examples are the Sichuan Basin and Appalachian Foreland Basin. Natural gas in the Sichuan Basin accounts for 98.76% of the total oil and gas production, which suggests that the basin is almost a super pure gas basin.
Table 1 Oil and gas production and oil-gas ratio of some super basins in the world.
| Basin | Oil output | Natural gas output | Total oil and gas output | Oil and gas proportions/% | Source | ||||
|---|---|---|---|---|---|---|---|---|---|
| 106 bbl | 108 t | 106 bbl | 108 m3 | 106 bbl | 108 m3 | Oil | Natural gas | ||
| Alberta WCSB | 40 530.02 | 55.28 | 36 682.26 | 60 243.28 | 77 212.28 | 124 537.34 | 51.63 | 48.37 | [34] |
| Williston | 10 327.50 | 14.09 | 1987.86 | 3264.66 | 12 315.36 | 19 647.51 | 83.38 | 16.62 | |
| Anadako | 2828.96 | 3.86 | 3908.49 | 6418.91 | 6737.45 | 10 906.58 | 41.15 | 58.85 | |
| Appalachian Foreland | 1337.29 | 1.82 | 10 292.49 | 16 903.36 | 11 629.78 | 19 024.74 | 11.15 | 88.85 | |
| Permian | 9106.78 | 12.42 | 4000.95 | 6570.76 | 13 107.73 | 21 017.14 | 68.74 | 31.26 | |
| Campos | 13 134.27 | 17.92 | 708.68 | 1163.87 | 13 842.95 | 21 999.18 | 94.71 | 5.29 | |
| Santos & Santos Deep Sea | 2285.06 | 3.12 | 369.48 | 606.80 | 2654.54 | 4231.66 | 85.66 | 14.34 | |
| Northwest German | 1919.00 | 2.62 | 5296.74 | 8698.84 | 7215.74 | 11 743.01 | 25.92 | 74.08 | |
| Timan-Pechora | 7024.28 | 9.58 | 2813.48 | 4620.58 | 9837.76 | 15 763.42 | 70.69 | 29.31 | |
| West Siberia | 100 496.85 | 137.08 | 130 529.20 | 214 368.11 | 231 026.05 | 373 789.47 | 42.65 | 57.35 | |
| North Ustyurt | 518.18 | 0.71 | 410.58 | 674.30 | 928.76 | 1496.30 | 54.94 | 45.06 | |
| North Carnarvon | 3062.88 | 4.18 | 5497.42 | 9028.41 | 8560.30 | 13 887.16 | 34.99 | 65.01 | |
| Songliao | 18 797.65 | 25.64 | 1014.14 | 1665.52 | 19 811.79 | 31 484.84 | 94.71 | 5.29 | This study |
| Bohai Bay | 17 030.79 | 23.23 | 1460.48 | 2398.55 | 18 491.27 | 29 415.04 | 91.85 | 8.15 | |
| Junggar | 2939.88 | 4.01 | 479.05 | 786.75 | 3418.94 | 5450.38 | 85.57 | 14.43 | |
| Tarim | 1788.86 | 2.44 | 2005.59 | 3293.78 | 3794.45 | 6131.50 | 46.28 | 53.72 | |
| Ordos | 3196.48 | 4.36 | 3005.53 | 4935.98 | 6202.01 | 10 006.66 | 50.67 | 49.33 | |
| Sichuan | 51.32 | 0.07 | 3950.45 | 6487.83 | 4001.77 | 6569.24 | 1.24 | 98.76 | |
Among the above classification of super basins in three different criteria, the classification in the geotectonic attribute does not change with the change of oil and gas production time. However, under the criterion of total oil and gas production, as time goes by, the category of first-tier super basins and second-tier super basins may change from second-tier super basins to first-tier super basins with the progress of oil and gas production. Under the criterion of oil and gas proportions, the category of super oil basins, super oil and gas basins, and super gas basins may also change with the change of the proportions of oil and gas production.
5. Conclusions
To classify the super basins in the first criterion, there are two conditions: (1) The cumulative output exceeds 50 × 108 BBL oil equivalent (6.82 × 108 t oil or 7931.66 × 108 m3 gas). (2) The remaining recoverable resources shall be at least 50 × 108 BBL oil equivalent. Those basins that meet the two conditions are called first-tier super basins, while those with slightly less cumulative production or remaining recoverable resources are called second-tier super basins. According to the geotectonic attributes of super basins, they can be divided into five categories: foreland super basins, intracontinental cratonic super basins, thrust belt super basins, rift super basins, and passive continental margin super basins. According to the oil and gas proportions in the total output of oil and gas, it can be divided into three categories: (1) Super oil basins, in which oil accounts for more than 80% of the total output; (2) Super oil and gas basins, in which oil accounts for 20%-80% of the total production; (3) Super gas basins, in which gas accounts for more than 80% of the total production.
The cumulative oil and gas production of the Sichuan Basin by the end of 2019 was 6569.24 × 108 m3 with the gas proportion of 98.76%, and the remaining recoverable resources amounted to 136 404 × 108 m3, so it is a super gas basin. The Sichuan basin can become a super gas basin because it has four advantages in natural gas geology: (1) There are nine sets of main gas source rocks (Doushantuo, Dengying, Qiongzhusi, Wufeng-Longmaxi, Qixia, Maokou, Changxing/Dalong, Longtan/Wujiaping, and Xujiahe formations), and the number of gas source rock sets is the largest in all basins in China; (2) The total recoverable resources are 156 482 × 108 m3, and the total remaining recoverable resources is 136 404 × 108 m3, ranking first among all basins in China; (3) The exploration and development of large gas field is an important way to rapidly develop natural gas industry. In 2019, there were 74 large gas fields in China, and their production and total reserves accounted for 76.5% and 76.5% of the total amounts, respectively. There were 27 large gas fields in the Sichuan Basin, accounting for 36.5% of the total number of national large gas fields, so it has the national advantage of large gas fields; (4) Total production advantage: the cumulative total gas production of the Sichuan Basin by the end of 2019 is 6488 × 108 m3, ranking first in all basins in China.
The Sichuan Basin has made four major breakthroughs in China's natural gas exploration and development: (1) A major breakthrough in shale gas production, successfully discovered and developed shale gas from Wufeng- Longmaxi formations; (2) A major breakthrough in tight sandstone gas, with the discovery and high recovery rate of tight sandstone gas reservoirs in member 2 of Xujiahe Formation in Zhongba gas field; (3) A major breakthrough in the giant carbonate gas field, successfully discovered and developed the Anyue giant carbonate gas field with the gas reserves exceeding 1012 m3; (4) A major breakthrough in ultra-deep gas reservoirs. Maokou Formation gas reservoir (7153.5-7175.0 m) in Laoguanmiao gas field is the first ultra-deep gas reservoir discovered in China, leading the exploration and development of ultra-deep gas fields (e.g., Yuanba, Longgang, Keshen, Dabei) in China.
Acknowledgements
The authors extend sincere thanks to senior engineer Zhao Zhe and Professor Wang Hongjun from Research Institute of Petroleum Exploration and Development, PetroChina for their help and guidance in collecting the relevant foreign super basin data in this study.
Reference
Geographical distribution of oil and gas discovered in ancient China
Developments in Mainland China
Geochemical characteristics of ultra-deep natural gas in the Sichuan Basin, SW China
DOI:10.1016/S1876-3804(18)30067-3 URL [Cited within: 4]
The four major onshore gas provinces in China
Super basins: New paradigm for oil and gas supply
DOI:10.1306/09182017314 URL [Cited within: 9]
2021-2025 is a period of great development of China's natural gas industry: Suggestions on the exploration and development of natural gas during the 14th Five-Year Plan in China
Chinese great advance: From a gas-shortage country to a giant gas-producer
May Sichuan Basin be a super petroliferous basin?
Some essential geological and geochemical issues about shale gas research in China
U.S. crude oil and natural gas proved reserves, year-end 2019
China’s shale gas exploration and development: Understanding and practice
A golden era for natural gas development in the Sichuan Basin
Geological characteristics of continental shale gas reservoir in the Jurassic Da’anzhai Member in the northeastern Sichuan Basin
Formation conditions and exploration and development potential of continental shale gas: A case of Dongyuemiao Member of the Jurassic in north Fuling area, eastern Sichuan Basin
Giant gas discovery in the Precambrian deeply buried reservoirs in the Sichuan Basin, China: Implications for gas exploration in old Cratonic Basins
DOI:10.1016/j.precamres.2015.02.023 URL [Cited within: 3]
Features and origin of natural gas in the Sinian—Cambrian of central Sichuan paleo-uplift, Sichuan Basin, SW China
The complexity, secondary geochemical process, genetic mechanism and distribution prediction of deep marine oil and gas in the Tarim Basin
Great discovery of oil and gas exploration in Cambrian Canglangpu Formation of the Sichuan Basin and its implications
New understandings and potential of Sinian-Lower Paleozoic natural gas exploration in the central Sichuan paleo-uplift of the Sichuan Basin
Sedimentary evolution characteristics and large-scale natural gas accumulation pattern of microbial carbonate in the slope area of major paleouplift, the Sichuan Basin
Distribution and exploration direction of medium- and large-sized marine carbonate gas fields in Sichuan Basin, SW China
DOI:10.1016/S1876-3804(19)30001-1 URL [Cited within: 1]
Distribution characteristics of gas pool in China
Geochemical comparison of the deep gases from the Sichuan and Tarim Basins, China
Genetic types of natural gas and gas-source correlation in different strata of the Yuanba gas field, Sichuan Basin, SW China
DOI:10.1016/j.jseaes.2019.103906 URL [Cited within: 1]
Petroleum exploration potential and favorable areas of ultra-deep marine strata deeper than 8000 meters in Tarim Basin
