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| | | | CNPC has established drilling technologies and capabilities applicable to various complicated surfaces and subsurface geological conditions.
Our drilling operations with complex borehole trajectory can be conducted to meet the demands of exploration and development for complex reservoirs, such as lithostratigraphic reservoirs, foreland basins and low-permeability reservoirs.
When drilling well Moshen-1 in Xinjiang, we safely set Φ244.5mm and Φ250.8mm tapered casings (523 tons in weight) down to a depth of 6,403 meters with a borehole deviation of 2.6°, despite the well's unfavorably high temperature and high pressure. This was thanks to the high pumping pressure and displacement, optimized drilling parameters, a high temperature and high density KDF water-based drilling fluid system and PDC drilling bits we selected.
 Ancillary Technologies for Rapid Drilling
The Sichuan Basin has the largest gas reservoirs in China. However, the region is characterized by complicated geological conditions. Factors such as high formation temperatures and pressures, a tendency for borehole collapse, borehole deviation, poor drillability and low drilling speed have long hampered gas prospecting and production there.
In order to raise the penetration rate, we researched technologies for rapid drilling at the Moxi and Qilibei gas fields of the Sichuan Basin by introducing air-drilling and gas-drilling technologies, optimizing well parameters, and carefully selecting drill bits and drilling fluids.
As a result, the average drilling speed has increased 2.6 times and the average drilling cycle has been reduced from 138 to 57.4 days. At the same time, the reservoir has been effectively protected and the output by under-balanced horizontal wells has increased to 3 to 8 times that of the vertical wells.
3000HP Rig for Ultra-deep Wells
We have developed and manufactured an AC variable-frequency electric rig for ultra-deep wells (9,000m+) and acquired the independent intellectual property rights. As well as having digitized AC variable-frequency controls, this highly reliable and adaptable new rig has a modularized design and a top-drive device.
This rig is resistant to temperature, leaks, erosion, explosions and sand. Our designers have managed to overcome several technological bottlenecks in crucial areas such as the control systems for the AC variable-frequency power output, single-shaft power transmission drawworks, high-pressure mud pumps and foundations for the heavy-load derricks. This rig now holds 5 national patents.
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