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Rotary-Shouldered Connections

Grant Prideco Inc. has introduced its TurboTorque rotary-shouldered drillpipe connections for extreme drilling environments (Fig. 1). The connection is designed for use in deepwater, ultradeepwater, extended-reach high-pressure/high-temperature, and horizontal wells to enable operators to drill deeper and faster than with conventional connections. In addition to faster makeup and breakout speeds, the connections deliver increased torque capacity, optimized hydraulics, improved clearance and fishability, reduced risk of failure, and extended life. The new connections provide better mechanical and hydraulic performance than earlier-model connections, yet they run as fast as or faster than standard connections. The family of connections was engineered and tested to validate design and performance across all sizes. Tests included finite-element analysis, stress-concentration-factor determination, torque to yield, multiple make and break, comparative fatigue testing, and multiple field trials. The connections are rotary shouldered with double-start threads. Dual-thread forms, 180° apart, reduce the number of turns from stab to makeup by 50%. The increased thread-lead angle provides an increased torque capacity of up to 12%. These connections are engineered for use with 130-ksi-specified minimum-yield-strength material, while meeting the increased fracture toughness required by proprietary manufacturing standards. In addition, the thread-form and tool-joint geometries were engineered to provide a step-change improvement in fatigue performance.

For additional information, visit www.GrantPrideco.com/TurboTorque.

Fig. 1—Grant Prideco Inc.’s TurboTorque rotary-shouldered drillpipe connection.

Downhole Rod Pump

Muth Pump LLC is replacing conventional sucker-rod-pump plungers with a new design. Solids (e.g., sand and coal fines) have plagued downhole pumps. The Farr plunger reduces plunger wear to reduce the chance of sand entry sticking the plunger in the barrel. Generally, conventional plungers have a 0.002- to 0.003-in. clearance between the plunger and the pump-barrel wall. However, the rod connector at the top of the plunger has a 0.06-in. clearance. This gap at the top of the plunger causes most of the problems associated with conventional plungers. As the plunger starts its upward movement, sand is forced outward into the gap because of the shape of the connector. When the well is shut in, even for a short period of time, sand will settle out and fall on top of the plunger connector. When the well is placed back on production and the plunger starts its upward movement, sand is wedged into the gap, sticking the plunger inside the pump barrel. In the Farr plunger, the connector was moved from the top to the bottom of the plunger (Fig. 2), which eliminated the 0.06-in. gap between the connector and the pump barrel at the top of the plunger. The angle at the top of the plunger was reversed to force sand inward. This new design allows sand to be pumped out of the wellbore with the fluid, thus reducing instances of sticking the pump with sand.

For additional information, visit www.muthpump.com.

Fig. 2—Conventional pump plunger on the left and Muth Pump’s Farr plunger on the right.

Subsea Boosting

Aker Kværner’s MultiBooster subsea multiphase-pump system (Fig. 3) increases oil recovery and enables longer step-out distances between subsea assets and host facilities by adding energy to the wellstream, which lowers the wellhead pressure and increases production rates. The design enables handling multiphase flow with a wide performance envelope and high-pressure boost at high gas content. The system consists of one or multiple booster units integrated into a subsea process system. The multiphase pumps can be arranged in parallel for increasing capacity of well-fluid boosting or in series for increasing differential boosting pressure for well fluid across the pumping process system. The multiphase-pump module uses twin-screw technology and consists of the pump unit and electrical motor in one common pressure housing; cooling and lubrication system, including accumulators; signals and high-voltage-electrical-power connectors and penetrators; controls and instrumentation; condition monitoring; and modular construction.

For additional information, e-mail neil.holder@akerkvaerner.com.

Fig. 3—Aker Kværner’s MultiBooster system deployment in the Lyell field offshore Scotland.

Riserless Drilling

The first North Sea well to use AGR Subsea’s Riserless Mud Recovery technology was drilled with a semisubmersible rig in 113 m of water. During the past 8 years, the company has developed methods to deal with seabed drilling-cuttings disposal, and then to eliminate the practice of “pump and dump” for tophole drilling by recovering the returning stream of mud and cuttings back to the rig rather than dumping it on the seabed. On the seabed, the riserless system has a 1-m-diameter suction module mounted on the drilling template and connected to the top of the well’s upper-conductor pipe, along with a nearby subsea mud pump (Fig. 4). This system sends drilling mud and cuttings back up to the surface drilling rig through an 8-in.-diameter flexible hose. Power and control systems also are carried on the rig. The emphasis on dual-gradient development in general has moved to tophole drilling. The system also was deployed off Sakhalin Island in eastern Russia and in the Barents Sea where drilling discharges are not permitted. Other applications have been in areas of poor hole stability, which require an engineered fluid system. The technology can be deployed in water depths to 400 m. Development work is under way to make the technology operational in water depths to 1500 m. Field trials at these depths are planned for 2007.

For additional information, e-mail sveinung.olsen@agr.no.

Fig. 4—The AGR Subsea Riserless Mud Recovery system.

Workflow Efficiencies

Landmark has released its Engineer’s Desktop (EDT) software Version 2003.16, which provides an integrated environment for well design and analysis, drilling, and completions by leveraging a common database for rapid access to information and safe data storage. The software provides an integrated engineering environment for one-time entry of design or actual data into a common database, which becomes accessible immediately to all other applications. Engineers can test various well configurations against other pre-entered data, and the multiuser environment allows several engineers to work on a common well design in a collaborative environment. Data ownership allows users to lock their data and applications, permitting only selected individuals to read or modify it. Both industry-standard and user-definable catalogs can be shared by all applications, ensuring data consistency between applications and reducing data errors. Information can be made available to the geosciences community through data sharing with common visualization, interpretation, and reservoir-modeling applications. A change to the reservoir model imposed by a geoscientist may affect well design and completion. The software environment enables quick changes to cascade through each application, updating every aspect of the design.

For additional information, visit www.lgc.com.

Subsea Production System

Cameron Intl. Corp. will supply Total E&P Nederland B.V. with its CameronDC all-electric subsea production systems (Fig. 5) for a multiwell subsea development in the North Sea. This system is powered by direct current. It has no batteries, hydraulics, or accumulators, and much of the conventional electrohydraulic equipment has been simplified or eliminated. The system provides production capability at virtually any water depth and at long-distance step-outs (beyond 100 miles). By eliminating hydraulics for power and signals, the control-system commands can be sent in rapid succession, thus avoiding the lag time required for accumulator charging. High-speed communication provides near-instantaneous communication with equipment as well as feedback on subsea conditions. The all-electric system eliminates the potential for hydraulic leaks and the issue of hydraulic-fluid disposal. This system includes an electric subsea-control module, a power-regulation and communications module, electrically actuated chemical-injection valves, annulus and production gate valves, and an electrically actuated choke.

For additional information, visit www.c-a-m.com.

Fig. 5—The CameronDC all-electric subsea production system for K5F field evelopment.

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