China National Petroleum Corp, the country's largest oil and gas producer and supplier, has been stepping up efforts in domestic oil field exploration and exploitation in the past few years, which has further enhanced the nation's energy security.

The company recently started drilling the Manshen-10 oil well with a depth of more than 9,000 meters in the Tarim Basin in the Xinjiang Uygur autonomous region, as part of its efforts to explore ultra-deep oil and gas reserves in the country.

Both the technology applied and the drilling depth are world-leading, said the company.

Located in the northern Tarim Basin, where the geological structure is extremely complex, the Fuman Oilfield area, the main block for crude oil production in the Tarim Oilfield where the Manshen-10 well is, is the country's demonstration area for efficient exploration and development of ultra-deep complex gas reservoirs.

So far, several wells around Manshen-10, including Guole-3, Manshen-301H, Manshen-5 and Manshen-8, have achieved major oil and gas discoveries 8,000 meters below ground.

The company has drilled 41 wells with a depth of more than 8,000 meters, breaking records at home and abroad. It has thus grasped the exploration and development technology of ultra-deep oilfields of more than 8,000 meters, it said.

Tarim Basin is a major petroliferous basin in China, producing one-sixth of the country's total natural gas. Tarim Oilfield said it expects 110 ultra-deep wells this year, while it drilled 23 wells with a depth of over 8,000 meters in 2021.

This is part of the latest efforts by CNPC in oil discovery and exploration in recent years. The company discovered a 1-billion-metric-ton super-deep oil and gas area in the Fuman Oilfield area last year, the largest discovery in the basin in nearly 10 years.

The drilling depth has reached 8,470 meters, and the height of the test oil column hit 550 meters, both marking new records for the deepest oil production and the highest oil column in the desert area of the Tarim Basin, it said.

In February, the company started drilling the Dabei-401 well at the southern foot of the Tianshan Mountains of Xinjiang. With a depth of 8,457 meters, the well is located where the geological structure is extremely complex, according to Tarim Oilfield of China National Petroleum Corp.

China has long relied heavily on oil imports in recent years. However, thanks to increasing efforts by domestic energy companies, including China National Petroleum Corp, China Petroleum and Chemical Corp and China National Offshore Oil Corp, in local oil field exploration and exploitation in the past few years, the country has witnessed a drop in crude imports and decreasing energy import dependency.

CNOOC, the country's top offshore oil and gas driller, for example, has a planned capital expenditure between 90 billion yuan ($14.14 billion) and 100 billion yuan for 2022, with exploration to account for approximately 20 percent of total spending.

Lian Weiliang, deputy director of the National Development and Reform Commission, said earlier that China will drastically step up investment in oil and gas exploration to increase reserves and production in the country.

According to the China Petroleum and Chemical Industry Federation (CPCIF), China's dependence on crude oil imports has dropped for the first time in the past two decades in 2021, from 73.6 percent in 2020 to 72 percent in 2021. Total crude imports declined 5.3 percent year-on-year last year to 513 million tons－the first time it has fallen in the past 20 years, it said.

The country's oil majors have ramped up exploration investment during the past few years with a batch of oil and gas fields coming onstream, which in turn contributed significantly to the country's decreasing reliance on oil imports, said Fu Xiangsheng, vice-chairman of the CPCIF.

According to Luo Zuoxian, head of intelligence and research at the Sinopec Economics and Development Research Institute, Chinese oil majors' consistent efforts have pushed forward the country's ultra-deep oil and gas exploration and development level.

Luo also said that with rising domestic oil and gas production, China is becoming more self-sufficient in energy supplies in recent years.

The country's oil behemoths' mastery of oil exploration technology is on the rise and has, in turn, injected momentum into China's future oil and gas systems and mechanisms, he added.

He suggested China further step up domestic oil and gas exploration, including unconventional oil and gas, as it is still heavily reliant on oil imports.