China on Thursday begun drilling a second borehole over 10,000 meters deep for scientific exploration in Sichuan Province, with workers having to overcome multiple hurdles brought by the complex geological structure. 

With a design depth of 10,520 meters, the borehole is located in Jian'ge County, in Guangyuan City of Sichuan. After the borehole is completed, it is expected that new trillion-square-meter-level gas fields may be discovered. 

The stratum in the Jian'ge area of Sichuan is complex, bringing great challenges to the drilling process. According to global standards on engineering difficulties, the drilling project covers seven world-class engineering problems. 

"The formation in Sichuan is relatively old, with relatively poor drill ability, making it difficult to drill through. In addition, we have more than 29 sets of multi-pressure systems, so the difficulty and risk in well control, oil and gas drilling, have reached the highest level in the world," said Luo Xin, general manager of the PetroChina Chuanqing Chuanxi Drilling Company. 

"This location has the geological conditions for drilling 10,000-meter-level wells. The formation has the conditions for gas generation, and it also has the aerosphere structure that makes good geological conditions for oil and gas accumulation," said Zhao Luzi, a technician with the PetroChina Southwest Oil and Gas Field Company. 

The whole drilling process will go through 650 million years of stratigraphic history, providing an opportunity to study areas of the planet deep beneath the surface. In addition to searching for oil and gas resources, the deep well can also play a role in studying the evolution of the earth, the origin of life and climate change.