On Drilling Rigs During the successful drilling process of Well Shenlidi - Takeke - 1 at a depth of 10,910 meters underground, the 10 - kilometer - long scientific exploration well has become a super project in the global oil and gas exploration field. There are more than 1,130 drill pipes connected end - to - end in the wellbore, with a self - weight of over 350 tons.
The thinnest drill pipe is only as big as the mouth of a cup, and the 10 - kilometer - long drill pipe is as soft as a noodle in the wellbore, with a high risk of fracture. To improve the drilling capacity of ultra - deep wells, most drilling equipment suppliers should focus on upgrading drilling rigs to enhance their capabilities and developing new drilling process equipment. Meanwhile, some research institutions have taken an alternative approach and carried out innovative work in terms of reducing the mass of the drill string, etc., proposing new ideas for light - weight high - strength steel drill pipes and non - steel material drill pipes.
Among them, relatively mature materials include aluminum alloy, titanium alloy, and carbon - fiber composite materials. Drill pipe materials need to be used in specific drilling environments under specific geological and technical conditions and should possess special physical and mechanical properties. The basic requirements for drill pipe materials for drilling operations are high specific strength, optimal elastic and shear modulus, corrosion resistance, wear resistance, etc. The aluminum alloy drill pipe was successfully developed by the Swedish Corrius Company in the 1960s. Some countries have carried out serial development and applied it to various well types in difficult - to - access areas, etc. For example, in the SG - 3 scientific ultra - deep well in the former Soviet Union, the proportion of aluminum alloy drill pipes used in the drill string reached 92% before the well was completed, making great contributions to the exploration of underground space.
The aluminum alloy drill pipe has the advantages of light weight, high specific strength, large drilling depth, and low energy consumption. It can be divided into three categories according to different joints, among which the one with steel joints is the most widely used. It can play the greatest role in well types such as horizontal wells, can reduce the weight of equipment, is convenient for transportation, reduces the hook load, shortens the operation time, and improves work efficiency and economic benefits. It has been successfully applied in "Songke - 2 Well", demonstrating its advantages such as reducing the power consumption of drilling rigs, but it also has problems such as low high - temperature strength and low self - hardness. Titanium alloy is a drill pipe material with strong physical properties, chemical corrosion resistance, and long service life. Its weight is about half that of steel drilling tools, and its flexibility is twice that of steel drilling tools. It is an excellent material for drilling wells with short radius, etc. In 1999, titanium alloy drill pipes were first put into commercial use, and they have been applied in hundreds of small - curvature wells in an overseas oilfield, and also in operations such as ultra - deep wells. They can reduce the hook load and torque, and improve the safety factor of drilling tools and the ability to handle accidents.
In 2023, two new high - toughness titanium alloy drill pipes independently developed by the China Petroleum Engineering Materials Research Institute completed their first down - hole tests in two ultra - deep wells in the Tarim Oilfield, filling the domestic R & D and application gap of 120 - ksi - level titanium alloy drill pipes. The carbon - fiber composite drill pipe is made of carbon fiber and epoxy resin, with a weight less than half that of steel and mechanical properties equivalent to those of steel. It can bring vitality to early idle oil wells and is highly economical compared to drilling new wells. In terms of cost, its production cost is 3 to 5 times that of the "standard" S - 135 steel drill pipe, but the total drill string cost/performance can be optimized and it can be "custom - made" for use in scenarios such as extended - reach wells, which can significantly reduce the transmission load and the supporting weight of the drilling platform and save costs.
In conclusion, light - weight drilling tools such as aluminum alloy and titanium alloy play important roles in ultra - deep drilling, "reduce the burden" on drilling rigs, and promote the continuous progress of oil and gas exploration and development towards deeper levels.