Entering the "deep earth" and seeking technological breakthroughs are the key

On the morning of July 20, the first 10,000-meter deep well in the Sichuan Basin, the "Shendi Chuanke 1 Well", was drilled in Jiange County, Guangyuan City, Sichuan Province, with a designed well depth of 10,520 meters. This is the second 10,000-meter deep well drilled in my country after the "Shendi Ta Ke 1 Well" in the Tarim Basin of Xinjiang on May 30 this year. The "Shendi Ta Ke 1 Well" has a designed depth of 11,100 meters, which marks the beginning of the "10,000-meter deep well" era in my country. The drilling completion cycle is 457 days, which will create the world's shortest record for drilling a 10,000-meter deep well.

In recent years, my country has been continuously advancing into the depths of the earth, breaking the record of "deep earth" development many times, and good news has been coming frequently. On the morning of May 1, Sinopec started drilling the "Deep Earth No. 1" ultra-deep oil and gas well, the "Yuejin 3-3XC oil and gas well", which was deployed on the edge of the Taklimakan Desert. The well is expected to be drilled to a depth of 9,472 meters, 620 meters more than the height of Mount Everest, and will break the record of the deepest oil and gas well in Asia. On the morning of May 2, another ultra-deep well "Deep Earth No. 1" located in the hinterland of the Taklimakan Desert with a depth of 8,591 meters, was drilled and the well test obtained a high-yield oil and gas flow.

The Tarim Basin is the largest inland oil and gas basin in my country. In its center, the Taklimakan Desert, there are currently 120 wells with a depth of more than 8,000 meters and more than 1,700 deep wells over 6,000 meters, accounting for more than 80% of the country's ultra-deep wells and more than 52% of the oil and gas production. These wells have a common task, which is to "invite" out the oil and gas buried thousands of meters under the desert. This task is also known as the "deep earth project." In August 2022, Sinopec Tarim Oilfield began to implement the "deep earth project" drilling in the Tarim Basin, which is a major project in the field of deep earth exploration in my country.

Going up to the sky, going down to the earth, going down to the sea, and reaching the top of the earth are the four great feats of human beings to understand and explore nature. What is the attraction of the "deep earth"? Because it hides the infinite mysteries of the blue planet Earth and the strong curiosity of human beings about the unknown. Carrying out deep earth exploration, innovating deep earth scientific theories, developing deep earth exploration technology, and explaining the mysteries of the deep earth have become important paths to solve the basic problems of energy resources and living space faced by mankind. Therefore, marching into the "deep earth" is an inevitable trend in the development of earth science, and deep earth drilling is the main means to explore these mysteries.

According to common international standards, wells with a depth of 4,500 to 6,000 meters are deep wells, wells with a depth of 6,000 to 9,000 meters are ultra-deep wells, and wells with a depth of more than 9,000 meters are extra-deep wells. Currently, three extra-deep wells with a depth of more than 10,000 meters have been drilled in the world.

my country has achieved the moon landing in the "deep space" and the deep sea with a manned submersible reaching the deepest part of the ocean and reaching the pole long ago, but the "deep earth" exploration has not yet exceeded 10,000 meters. Going beyond the limit and drilling a 10,000-meter ultra-deep well is an inevitable requirement for my country to achieve high-level scientific and technological self-reliance.

"Rich in coal, poor in oil and little in gas" is the current situation facing my country's energy development. Before the large-scale application of new energy, fossil energy is still an important resource for economic and social development, and 83% of my country's deep-earth oil and gas are still to be explored and developed. Entering the deep-earth has become an inevitable choice to ensure national energy security.

As one of the important means of entering the earth, deep drilling is regarded as a "telescope" that penetrates deep into the earth. The average radius of the earth is known to be 6,371 kilometers, but the vertical depth of human deep drilling is only 12.262 kilometers, which means that humans have spent 300 years digging less than 0.2% into the center of the earth. If the earth is compared to an egg, then even the eggshell has not been drilled, so advancing into the deep earth is no less difficult than climbing to the sky.

So, what is the difficulty in advancing into the deep earth? The first problem is high temperature and high pressure. As the drilling depth continues to increase, the temperature and pressure of the formation will gradually increase. The high temperature of more than 200°C in the 10,000-meter formation can make metal drilling tools as soft as noodles, and the high-pressure environment of nearly 1,300 times the atmospheric pressure, or even more than 100,000 atmospheres, also brings unprecedented challenges to tools, equipment, engineering materials, etc. At the same time, when the thousands of connected drill pipes in the wellbore transmit power to the drill bit, the dead weight of six or seven hundred tons will also bring great load to the drilling rig. Drilling itself will also encounter many "gates of hell" such as easy leakage, easy collapse, and easy jamming.

In the Tarim Basin and Sichuan Basin, most deep-earth drilling in my country is even more difficult. The ultra-deep wells drilled in the Tarim and Sichuan Basins this year have been benchmarked against 13 global engineering difficulty indicators, with seven of them ranking first in the world, including high temperature, high pressure, and high sulfur content.

Therefore, seeking technological breakthroughs is the key in the process of advancing into the deep earth. The deeper the drilling, the more advanced the technology is needed. In recent years, the rotary geosteering drilling system independently developed by Sinopec has reached the international advanced level, and the high-temperature and high-pressure logging instruments independently developed have broken the foreign technology monopoly and achieved a leap from "unable to drill" to "accurately drilling" and "fast drilling". All of this has made my country's mainland scientific drilling rank among the top in the world's deep geological research.

(The author is a member of the Hunan Science Writers Association)