Xi-jie Chen, Li-qiong Jia, Ting Jia

Development and Research Center of China Geological Survey, Ministry of Natural Resources, Beijing 100037, China

2021 is the year with the least amount of oil and gas exploration and discoveries in the past 75 years. The world’s new proven oil and gas reserves were 6.6×109barrels of oil equivalent, compared with 19×109barrels of oil equivalent in 2020, with a significant decline in new proven oil and gas reserves.

In 2021, the three major oil companies of China,PetroChina, Sinopec and China National Offshore Oil Corporation (CNOOC), achieved good results in the exploration and development of oil-shale gas-coalbed methane -unconventional oil and gas which is mainly reflected in three aspects, the first is to achieve a breakthrough in 7500 m deep exploration, the second is a breakthrough in offshore oil and gas exploration, and the third is a major breakthrough in unconventional shale oil exploration, adding 5.393×109t of proven oil and gas reserves. The following highlights the top 10 achievements of China ’s oil and gas exploration in 2021.

(i) “Bozhong 13-2 ” in Bohai Oilfield discovered a 100 million-ton scale oil and gas field. On February 22, 2021,CNOOC announced that the oil and gas field is located in the central waters of the Bohai Sea, about 140 km away from Tianjin, with an average water depth of about 23.2 m. It belongs to the type of buried hill covered by the sea area, and has important promotion value for the future exploration of the same type of buried hill in the Bohai Sea and offshore China.

(ii) The “Kenli 10-2 ” billion-ton scale oil and gas field was discovered in Bohai Oilfield. On September 30, 2021,CNOOC announced that the oilfield is about 245 km away from Tianjin City, with an average water depth of about 15.7 m, drilling into an oil layer of 27 m, and drilling to a depth of 1520 m. The daily crude oil production per well can reach 81.55 t. This is the first time that a 100-million-ton scale lithologic and lithologic reservoir has been obtained in the shallow layer of the sag belt of the Bohai Oilfield, which has broad exploration prospects.

(iii) “Huizhou 26-6 ” in the eastern South China Sea discovered a 50×106m3oil equivalent oil and gas field. On January 25, 2021, CNOOC announced that the oil and gas field is located in the Pearl River Mouth Basin of China, 162 km southeast of Hong Kong SAR, with an average water depth of about 113 m, and the thickness of the oil and gas layers drilled by exploration wells is about 422.2 m,belonging to the ancient buried hill type in the sea. The daily output of the test well exceeds 500 m3of crude oil and more than 60 m3of natural gas, breaking the 40-year history of no commercial discoveries in the area and showing good exploration prospects.

(iv) A tight gas field with reserves of 101×109m3was discovered in Linxing, Shanxi. On February 28, 2021,CNOOC announced that the gas field is located in the Carboniferous-Permian in the Linxing area of the Jinxi flexural fold belt in the eastern Ordos Basin. It is a “multilayer and quasi-continuous” accumulation model. In the next three years, the Linxing gas field will build a large gas field with an annual output of 2.7×109m3.

(v) The Ordos Changqing Oilfield discovered 1×109t of shale oil. On June 20, 2021, PetroChina announced that the oil field is located in the laminar shale of the Chang 7 Member of the Triassic Yanchang Formation in the Ordos Basin. Since the discovery of the Qingcheng shale oil field in 2019, the cumulative proven reserves so far have reached 1.052×109t. It is the largest shale oil integrated oilfield with the largest proven reserves in China. For the first time, the oilbearing mechanism and new accumulation model of mud shale in large inland freshwater lake basins have been revealed.

(vi) On August 25, 2021, Daqing Oilfield announced that 1.268×109t of shale oil was discovered in Gulong shale oil of Daqing Oilfield. Daqing Oilfield, discovered on September 26, 1959, is a world-class super-large sandstone oilfield. The annual oil output from 1975 to 2002 was 50×106t, the annual oil output from 2003 to 2014 was 40×106t, the annual oil output from 2015 to 2019 was between 3850 t and 3200 t, and it reached 43×106t in 2020. The oil field entered an unstable period of withering. In recent years, Daqing Oilfield has introduced unconventional oil and gas theory to guide oil and gas exploration, and discovered 1.268×109t of shale oil in the shale of the Upper Cretaceous Qingshankou Formation in the Songliao Basin, which has brought new life to Daqing Oilfield.

(vii) Shengli Oilfield in Shandong Province has discovered 458×106t of shale oil, with prospective reserves of 1.85×109t. In October 2021, Sinopec announced that Well Fanyeping 1 deployed in the fourth member of Shahejie Formation in Boxing Sag of Jiyang Depression achieved peak daily production of 171 t of oil and 16000 m3of gas. For the first time, a breakthrough in the commercial productivity of shale oil in the Jiyang Depression has been achieved, proving that matrix shale oil with a medium degree of evolution has good development value.

(viii) 350×106t of shale oil resources were discovered in the North Jiangsu Basin. On December 15, 2021, Sinopec announced that shale oil was discovered in Well Shaduo 1 in the risk exploration of the second section of the deep-sag zone in Qintong Sag, North Jiangsu Basin, with a maximum daily oil production of 50.9 t and a resource of 350×106t. The newly added oil reserves are 31.86×106t. The discovery has important guiding significance for the exploration of shale oil in small and medium-sized fault depression basins in the East China.

(ix) A one billion-ton scale ultra-deep fault-controlled super-large Fuman oil and gas field was discovered in the Tarim Basin. On June 18, 2021, PetroChina announced that the oil and gas field is located in the Fuman area in the hinterland of the Taklimakan Desert and the southern part of the Tarim River. The drilling depth reaches 8470 m, and the test oil column height reaches 550 m, setting the deepest oil production record and the highest oil column height record in the large desert area of the Tarim Basin, and confirming the ultra-deep fault-controlled oil and gas reservoir area of about 20000 km2.

(x) The Shunbei oil and gas field in the Tarim Basin has obtained a new block of 100-million-tons scale. In August 2021, Sinopec announced that the oil and gas field is an ultradeep carbonate oil and gas field. The key exploration well deployed in the Tarim Basin in 2021, Well Shunbei 44X, has obtained a daily oil and gas equivalent output of over 1000 t,marking the major discovery of the 100-million-ton scale oil and gas area in the No. 4 fault zone of the Shunbei Oil and Gas Field. So far, the proven oil and gas reserves of the No. 4 fault zone have exceeded 200×106t.

At the same time, in 2021, China’s domestic production of crude oil will be 198.976×106t, a year-on-year increase of 2.4%; natural gas production will be 205.26×109m3, a yearon-year increase of 8.2%. The 2021 production for the Big Four oil and gas companies is as follows:

(i) PetroChina: In 2021, the output of oil and gas will exceed 210×106t, the output of natural gas will exceed 100×106t, and the output of crude oil will continue to grow for three years. There are three main oil fields, and the production volume is: (1) Changqing Oilfield is the largest oil and gas field in China, and it is also the oil and gas field with the largest oil and gas production in the past 10 years. In 2021, it will produce 25.36×106t of crude oil and 46.5×109m3of natural gas. Oil and gas production equivalent reached 62.44×106t. (2) Daqing Oilfield will produce 30×106t of domestic crude oil and 5.02×109m3of natural gas in 2021.Oil and gas production equivalent reached 43.22×106t. (3) The oil and gas production equivalent of Tarim Oilfield will reach a record high of 31.82×106t in 2021, achieving an increase of over 1×106t for five consecutive years.

(ii) Sinopec: In 2021, it will produce 35.15×106t of crude oil and 33.9×109m3of natural gas, an increase of 12%.Among them, Sinopec Shengli Oilfield has made outstanding achievements in exploration and development. The oil and gas equivalent of Shengli Oilfield in 2021 will be about 23.9×106t,and four major breakthroughs and four commercial discoveries have been made, consolidating the foundation for stable production in the old area, and the effective and stable production of more than 23.4×106t for five consecutive years.

(iii) CNOOC: CNOOC ’s domestic crude oil production was 48.64×106t, a year-on-year increase of 3.23×106t, and the increase accounted for about 80% of the total domestic crude oil increase.

(iv) Yanchang Petroleum Group: In 2021, the oil and gas equivalent of Shaanxi Yanchang Petroleum Group will reach 16.6×106t, ranking the eighth largest oil and gas field in China, of which 11.3379×106t of crude oil will be produced.

(According to the data of the Ministry of Natural Resources and major oil and gas companies)