Application of Aluminum Alloy Tube Semis: Problems and Solutions in the Development of Exploration, Production and Transportation Business of Hydrocarbons in the Arctic
Authors: Gelfgat M.. , Chizhikov V.. , Kolesov S.. , Alkhimenko A.. , Shaposhnikov V.. 
Published: October 2013

This article continues and extends the topic addressed at the last conference held in Moscow in 2011 – prospects of aluminum tubes in well construction in the Arctic1. In addition to well-known successful practices of using aluminum drill pipes, it highlights the results of manufacturing and application of tubing and casing, as well as risers made of structural aluminum alloy tube semis (SAA). Attention is also paid to the fact that though there are some obvious and proven SAA advantages in comparison with conventional tube semis, application of aluminum tubular products remains rather limited. This circumstance can be explained by certain conservatism of the engineering community that still relies on generally accepted dogmas of aluminum alloy deficiencies. These include low hardness contributing to increased wear of the surface in contact with rock or other material and limited corrosion resistance in some conditions, for example, with increased chloride content. Many experts believe that these negative circumstances prevail over such advantages as hydrogen sulfide corrosion resistance, stability of properties at low temperatures and, finally, a huge advantage in strength-to-weight ratio of the tubular structure – a freely suspended SAS string is almost twice as long as the string made of steel. Such approach, subject to a wide offering of advanced high-strength steel tubes and special alloy tubes resistant to hydrogen sulfide corrosion, helps to solve current problems in a traditional conservative way. However, increasingly difficult conditions of field development result in substantially higher costs of well drilling, completion and operation, and the Artic is one of the brightest examples of this tendency. This is precisely why the authors again offer to consider alternative "aluminum" solutions of the problems.

The article describes the results of using advanced techniques for SAA surface treatment that enable to minimize low strength and wear problems. Among them are ultrasound treatment and different coatings. Also, the examples of solutions are given that enabled adaptation of SAA tubes for use in corrosive environment – 7" production casing installed in the well with more than 18 % hydrogen sulfide content in the produced oil; 22" offshore drilling riser operated at the water depth of more than 2,000 meters. Business success by enjoying SAA advantages is possible when a comprehensive multidisciplinary approach is used to design tubular or other structures for operations in extreme conditions whether these are drilling pipes, tubing or casing, risers or pipelines. The experience in other industries, for example, in shipbuilding, demonstrates the possibilities for solving great challenges by combining the efforts of experts in the sphere of materials science, metallurgy, machine building and structural design in this industry. In view of the tasks that are set, in particular, in arctic field development, building of specialized expert teams on the base on well-known research centers and scientific communities will allow making effective innovative decisions promptly and with the required reliability.