Aluminum alloys continue to be among the promising materials for manufacture of drill pipes and risers for deepwater and ultra-deepwater environment. Steel tool-joints attached to aluminum alloy pipes increase the number of make-ups and break-outs. Currently, aluminum drill pipes (ADP) are assembled by “cold” or “hot” methods. By the first method, the pin and box are screwed on the pipe with a “sufficiently” high specified make-up torque. By the second method, the pin and box of the tool joint are heated and screwed on the ends of the pipe without effort. After cooling, the shrinkage of the tool joint units creates a reliable permanent threaded “pipe – tool joint” connection. The first method is easier than the second one; however the comparative strength of these ADP connections has not been enough clear. The paper presents the results of comparative strength analysis of both types of connection after assembly at applying tensile load and alternating bending load. The theoretical aspect of the study includes a detailed FEA of “hot” and “cold” assembly connections at applying tensile load and alternating bending load with SCF evaluation. The experimental data are presented as the results of tensile testing of small-scale specimens, removed from different aluminum pipe sections that were heated during “hot” assembly. Finally, full-scale specimens of both types of connections were tested for tensile capacity and fatigue. The comparative strength of both types of connections is concluded.

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Slips, slip elevators, spiders, etc. have been widely used as oilfield service tools to grip and hold drill pipe, drill collars and casings by acting as a wedge. A pipe in a slip with a conical bearing surface is subjected to complex loads comprised of tensile, compressional, radial and bending stresses. To increase the holding force, the bearing surface of the gripping device in the form of a dies set is provided with teeth penetrating into the pipe body. This generates additional drag force on the contact surface that supplements the friction force. This paper presents a new slip model, which uses the dependence of the drag force on the teeth penetration depth. The model is based on an improved dependence of the drag of wedge-shaped die teeth not only on the friction force in the "die-pipe" pair but also on the shearing force arising during teeth penetration in the pipe body. Equation parameters have been verified by multiple finite element (FE) calculations and experimental studies of dependence of the penetration force on the drag of a single tooth. The developed equations are used in the complete drillpipe-slip model. It accounts for pipe wall deformation under compressive stress generated by the slip and the drillstring weight and determines the active bearing length of the slip under load. The paper presents calculations of allowable areas for a slip of a specified length equipped with toothed dies based on the load carrying capacity and pipe strength. The proposed model can be used for operative calculations of the slip carrying capacity, as well as for the development of new slip designs.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOil and Gas industry requires a significant amount of tubular goods to meet their operational objectives. Drill pipe, casing, tubing and risers must be designed and manufactured to accommodate present and future tendencies of drilling deeper, longer, faster and more efficiently while maximizing production for every well drilled. The most important feature of aluminum alloys used as materials for tubular manufacturing is that they provide exceptional strength-toweight ratio. This simply means that the length of aluminum alloy pipe string suspended under its own weight would be about two times longer than steel. This feature allowed development of aluminum drill pipe which has an excellent potential in extended reach drilling of wells of 15 km long. The last five years of field applications in West Siberia have proven that ADP has high reliability and life expectancy. Equally superior performance is projected for aluminum casing, tubing, and line pipe. Use of aluminum drilling riser strings in deep waters of offshore Brazil and GOM helped to establish that aluminum alloy is very reliable construction material for some of the most difficult applications in the petroleum industry. This experience provides us with confidence in continuing to develop new products for the industry, such as completion and production risers.

The purpose of this work is to analyze the prospects for efficiency increasing of high-tech wells construction using a drilling complex based on downhole permanent magnet motor. For the first time, the article provides information about new drilling complex. Considered technology could provide a breakthrough in drilling high-tech wells. This technology combines advantages of drill string with electric wire and an ideal downhole motor with a wide rotational speed range, regardless of the type and flow rate of circulating agent. The article provides a brief comparative analysis of electrodrilling implementation results "generation 70s", the composition of new electric drilling complex and its difference from the previous one are considered in details. Complex meets the requirements of high-tech wells construction and allows automating drilling process using ultra-high-speed bi-directional data transmission channel and quickly assessing the parameters of drilling regime and direction of drilling, characteristics of rocks, pressure and temperature distribution along the wellbore. Permanent magnet motor ensures optimum drilling parameters for rock destruction at the bottomhole, regardless of the well profile and the type of circulating agent, including managed pressured drilling. Effectiveness of accidents prevention and mitigation is increased. Authors propose to discuss the prospects of electrodrilling technology using downhole permanent magnet motor, which is currently at TRL-3 level, to assess and specify adopted concept of electrical drilling complex development.