Aluminium drillpipe (ADP) is being recognized by major drilling companies as an instrument for reducing drillstring weight and consequently torque and drag. This product has been used in Russia since the 1960s. The combination of the low-capacity drilling rigs, ADP, and turbodrills provided a unique opportunity for development of remote Western Siberia deposits, using cluster directional-drilling technology. The modified aluminium alloy drillpipe known as LAIDP (light-alloy improved dependability pipe) was later introduced for ultradeep wells. This design allowed high-torque application, resulting in the achievement of a world record in drilling 12,262 m in the Kola SG-3 well in 1993. Though LAIDP was initially designed for ultradeep drilling, it has been successfully applied in deep oil and gas exploratory and development drilling, especially in horizontal boreholes, since the early 2000s. The untapped potential of LAIDP is significant. Its successful application in the Arctic and other extreme environments can use this potential and become a catalyst for industry growth.Rough weather, extremely low temperatures, ice, and lack of infrastructure have always made drilling in the Arctic extremely difficult, especially for offshore fields. One of the solutions, in this case, is reaching the target from shore or from an artificial island, using extended-reach drilling (ERD). Existing ERD technology provides wells with horizontal extensions up to 11.5 km. The record ERD well, completed in 2011 at Odoptu field, Sakhalin-1, has reached 12,345 m length. In spite of these amazing results, the industry needs longer wells. LAIDP and similar technologies could advance borehole length for an additional 5 km, as shown by analyses conducted in the past few years. Extensive laboratory tests and field trials would provide more confidence in a 15-km to 20-km well as a target in the near future. Such a possibility may be crucial for development of a number of oil and gas fields in the Arctic.Light alloy pipes would provide other benefits as well, among them, easier transportation and resistance to cold environments.Other important properties of ADP may be found useful, such as corrosion resistance to hydrogen sulfide (H 2 S) and carbon dioxide (CO 2 ), nonmagnetic properties, and good flexibility.

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Development of oil and gas fields with high H 2 S and CO 2 content in formation fluids is one of the challenges for modern technology. Conventional steel casing and tubing strings cannot be used in such environments as they are much prone to corrosion, while the use of specialized corrosion-resistant tubulars with high content of chrome makes well construction and operation times more expensive.Such extreme operating conditions prevail in the fields located in the North of Komi Republic, where H 2 S content is above 15%. In addition to the corrosive environment of the wells, the drilling rigs, which operate in the area have limited load capacity and therefore face difficulties in running a single-section casing strings to depths over 4000 meters.A very promising approach to elimination of these problems may be the application of aluminium alloy casing pipes developed by Aquatic Company. It is known that aluminium alloy pipes remain inert to corrosion even if the formation environment is fully saturated with H 2 S and/or CO 2 . They are also light-weight, have high strength-to-weight ratio, and thus decrease the existing tensions in the string and reduce well construction costs. Description of the oilfield for application testBayandyskoye oilfield, belonging to "LUKOIL-Komi" LLC, where aluminium casing and tubing were planned for trial application, had the major problem of hydrogen sulfide presence in formation fluids: up 18.5% vol. in the Zadonsky horizon of Upper Devon and carbon dioxide up to 1.1% vol. Besides, well conditions were characterized with high formation pressures up to 27 MPa and temperatures up to 90°C.Prevalence of such aggressive conditions set special requirements for well construction, casing, completion type, wellhead, BOP and drilling equipment, as well as for locations of drilling equipment.Because of these reasons, the first two exploratory wells on the Bayandyskoye oilfield were drilled from rigs equipped with a power top drive, with corrosion-resistant BOP with blind rams, pipe rams and shear rams, and with an annular preventer. Initially aluminium tubulars were not considered for the design of the well.The well construction of first two exploratory wells was rather metal-intensive and costly. It included two intermediate strings (D=323.9 mm, L=2460 m and D=244.5 mm, L=3483 m) and a production string D=168.3 mm to target depth of 4588 m.Great care was exercised when selecting the material for casing and their leak-proofness. The upper section of the second intermediate string (D=244.5 mm) utilized 90SS pipes of strength group, and the lower section was made of Sanicro 29 (110) stainless steel pipes.All casing pipes came with highly sealed Tenaris Blue threaded connections. Casing equipment (stage cementing collars, packers, valves) was also made with similar high-strength corrosion-resistant steel grades.The intermediate strings were run in hole by sections with the use of docking tools, which increased the time of construction, risk of faults and emergencies in the process of running in ...

When selecting a casing material for fields with a high content of H2S and CO2, it is recommended to use specialized corrosion-resistant tubulars with high content of chrome of the Sanicro 29 type. The high cost of the material can be critical for the project economy. A promising approach for these problems elimination could be the application of aluminium alloy casing pipes. They are remain inert to corrosion even if the formation environment is fully saturated with H2S and/or CO2. They are also lightweight, have high strength-to-weight ratio, and thus decrease the existing tensions in the string and reduce well construction costs.