China's three oil majors all reported first-half net profit surges, with their combined bottom lines exceeding 197 billion yuan ($28.49 billion), riding on an increase in oil and gas output and higher energy prices.

China Petroleum and Chemical Corp (Sinopec), the world's largest refiner by capacity, reported that net income in the first six months surged 10.4 percent year-on-year to a record 43.53 billion yuan while revenue was up 27.9 percent from a year earlier at 1.61 trillion yuan, thanks to strong oil and gas prices despite weakened domestic fuel sales.

PetroChina Co Ltd, the listed arm of China National Petroleum Corp, earlier reported a net profit of 82.39 billion yuan in the first half, an increase of 55.3 percent year-on-year. Its first-half revenue rose 35 percent year-on-year to 1.6 trillion yuan, it said.

Meanwhile, China National Offshore Oil Corp Ltd more than doubled its first-half net profit, with its bottom line surging 115.7 percent year-on-year to 71.89 billion yuan while revenue was 75.6 percent higher at 176.68 billion yuan.

An analyst said the historic net profits for Chinese oil giants in the first half was due to surging prices for oil and gas as well as their continuous efforts in speeding up domestic oil and gas exploration over the past few years.

Luo Zuoxian, head of intelligence and research at the Sinopec Economics and Development Research Institute, said China's crude output should reach 200 million metric tons this year.

Luo said he expects a turnaround in the economy to bolster results going forward and the companies are also likely to accelerate spending in the second half as they seek to keep growing oil and gas output to help safeguard the nation's energy security.

The oil majors all stepped up investment in domestic oil and gas exploration amid rising energy prices.

Sinopec said it produced 34.04 million tons of oil and gas equivalent in the first half, up 2.9 percent year-on-year. The company's exploration and development division achieved an operating income of 26.3 billion yuan, up 322 percent year-on-year.

While PetroChina recorded a 3.4 percent year-on-year growth in domestic oil output and a 4.4 percent rise in domestic gas production, CNOOC Ltd has also stepped up oil and gas production during the first six months, with net oil and gas production hitting a record high of 304.8 million barrels of oil equivalent, a year-on-year increase of 9.6 percent, the companies said.

The oil and gas giants are also laying out new energy-related plans as the country goes full throttle on its green energy transition with an aim of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060.