Due to its deep depth, high formation pressure and temperature, and complex geological conditions, deep well drilling has very high performance requirements for seamless casing pipe. The following grades of seamless casing pipe are more suitable for deep well drilling:

N80 steel grade
1. Performance characteristics
It has good strength and corrosion resistance, with a yield strength between 552-758MPa and a tensile strength of ≥689MPa, and can withstand certain formation pressure and corrosive environment.
2. Applicable scenarios
It is suitable for deep wells with relatively uncomplicated geological conditions and not particularly deep wells, such as deep wells with a depth of about 3000-5000 meters, and relatively weak formation corrosion.

L80 steel grade
1. Performance characteristics
It is a chromium alloy steel with good corrosion resistance, especially hydrogen sulfide corrosion resistance, yield strength of 552-655MPa, and tensile strength of ≥655MPa.
2. Applicable scenarios
If the deep well contains corrosive gases such as hydrogen sulfide, L80 steel grade seamless casing pipe is a better choice and can be used for deep wells of about 5000-6000 meters.

P110 steel grade
1. Performance characteristics
It has higher strength, yield strength 758-965MPa, tensile strength ≥862MPa, and can withstand greater formation pressure and tensile force.
2. Applicable scenarios
It is suitable for ultra-deep wells with a depth of more than 6000 meters, or deep wells with complex geological conditions and high formation pressure.

Q125 steel grade
1. Performance characteristics
It is a higher strength steel grade, with higher yield strength and tensile strength than P110, and has excellent anti-squeezing and anti-tensile properties.
2. Applicable scenarios
It is mainly used for extremely deep wells or ultra-high pressure deep wells, such as deep wells above 7000 meters, and can maintain good performance under extreme pressure and complex geological conditions.

Summary
In short, when facing the extremely challenging task of deep well drilling, it is crucial to accurately select the appropriate seamless casing pipe grade. Different steel grades such as N80, L80, P110 to Q125 each cope with various formation depths and complex conditions with their unique performance. Only by weighing key factors such as strength and corrosion resistance based on actual well conditions and rationally selecting seamless casing pipe can we lay a solid foundation for deep well drilling operations, ensure the smooth progress of the project, open the door to deep underground energy treasures, and help oil and gas resource development to a new level.