How Long Does It Take to Drill an 8,000-Meter Deep Well?

Drilling a well deeper than 8,000 meters is never just a question of time. It is a test of technology, endurance, and engineering limits. In China’s Tarim Basin, we have been pushing further into the Earth’s depths year after year, facing some of the most complex geological conditions on the planet.

So how long does it actually take to complete an ultra-deep well?

The answer has changed dramatically over the past two decades.

In 2007, drilling a well beyond 8,000 meters typically required more than 700 days. By 2015, that figure was reduced to over 400 days. In 2018, it dropped again to around 300 days. Today, the average drilling cycle is about 220 days. In the Fuman Oilfield, the fastest 8,000-meter-class well has been completed in just 118 days.

This progress is not accidental.

The Tarim Basin holds a significant share of China’s ultra-deep oil and gas resources. More than 80% of the country’s resources deeper than 6,000 meters are concentrated here, accounting for nearly one-fifth of the world’s ultra-deep reserves. At the same time, the region is known for extreme drilling difficulty. Among the industry’s 13 recognized drilling challenge indicators, Tarim ranks first in five categories.

For many years, complex formations, such as thick, steep gravel layers, severely limited drilling speed. Traditional roller cone bits and conventional PDC bits wore out quickly, required frequent replacement, and extended single-well drilling cycles to over 500 days.

We realized that the breakthrough had to start with rock-breaking technology.

By continuously testing new drilling tools and bottom-hole assemblies, we introduced a composite rock-breaking concept that combines localized high stress with compression, tension, and shear. This led to the development of new hybrid drill bits featuring multi-edged teeth, conical teeth, and arrow-shaped polyhedral cutters. These designs significantly improved impact resistance and adaptability in hard, abrasive formations.

At the same time, we optimized drilling assemblies using vibration reducers or mud motors, vertical drilling systems, and high-efficiency PDC bits as an integrated solution. This combination has now been applied in over 90% of complex wells, increasing single-bit footage and mechanical drilling speed by more than 50% compared with neighboring wells that did not use the technology.

The results speak clearly.

So far, 72 wells deeper than 8,000 meters have been drilled in the Tarim Basin. Several wells have repeatedly set new regional records for drilling cycle time, proving that deep and ultra-deep drilling can be both faster and more controllable.

Through sustained technical innovation, we have built a drilling acceleration system with independent intellectual property rights. These technologies are now fully integrated into geological-engineering planning and applied across the field.

As we continue to move toward deeper targets, each meter drilled represents not only progress in depth, but also progress in capability. Ultra-deep drilling remains challenging, but the path forward is becoming clearer—and faster—than ever before.