20000psi！MHWirth立管見證歷史一刻

To meet market demands for higher performance in riser technologies, MHWirth has developed the QRT 4000 LS drilling riser system. It can operate at up to 20,000 psi and in up to 10,000 ft of water. The water depth rating can be increased to 15,000 ft by using the QRT 5000 LS.

The goal in designing the system was to reduce cost of ownership by reducing maintenance cost and increasing the ability to perform offshore inspections. After in-depth review, the scope of the project was determined as follows:

? Increased possibility to trip more than 10 joints per hour;

? Maintain connection time as the present system or better;

? Increase stabbing tolerances to reduce stabbing time;

? Replaceable peripheral line boxes and pins without welding;

? Ability to replaceable lock ring on main pipe offshore;

? Ability to inspect critical areas of the connector offshore;

? Reduce critical fasteners to reduce inspection requirements;

? Make the connection scalable from 2,500 kips to 5,000 kips with 15,000- and 20,000-psi rating on kill and choke lines;

? Up to eight peripheral lines;

? Temperature rating of 350°F;

? Distribute load through the kill and choke line;

? Protect the peripheral line seal areas while stabbing to reduce scouring;

? Torque to be taken through the main pipe and not loaded through the peripheral lines;

? Optional hands free connection to optimize HSSE;

? Clear indication on connector indicating when the connector is closed or open;

? Connector design compliance with API 16R, 16F and 16C; and

? DNV-GL and ABS type approval certificates.

After completing the conceptual design, another round of presentations and feedback from users was conducted before finalizing the design. The design work included elastic and plastic analysis of the connector, connector design optimization, kill and choke line thread design, dynamic riser stabbing analysis and riser thermal performance analysis. In addition, dynamic analysis of riser stabbing was performed to optimize the connector self-alignment, obtain smooth and safe stabbing and establish maximum stabbing speed and operating envelopes.

The project underwent qualification and verification in accordance with DNV-RP-A203 “Qualification of New Technology” and API 16R. In addition, ABS helped to establish the qualification program and subsequent testing.

A decision was made to produce prototypes of the 4,000 kips connector and perform the qualification tests on this system first. DNV-GL conducted tests on the connector in Norway, including stabbing and makeup tests, pressure tests to 7,500 psi, connector fatigue tests, system load sharing tests to 5,620 kips and low cycle tests. The kill and choke line threaded connections were fatigue tested at SINTEF in Norway. The qualification tests confirmed the design work and showed that the connector performed better than the requirements. Type approval was obtained from DNV-GL and ABS.

The riser system is designed without high-strength bolts, thus removing the risk for hydrogen-induced corrosion. It can utilize a thermal sprayed aluminium coating for added corrosion resistance.

The spider/gimbal system was redesigned to reduce weight and height. The spider and gimbal are integrated into one unit without any critical welding, thereby reducing the inspection requirements and increasing the possibility to do offshore maintenance and repair. The spider can be outfitted with a hydraulic unit for hands-free closing and opening of the connector and guides.

Tripping speeds reported with the new riser system has been up to 12 joints per hour. Further, MHWirth is working to certify a condition-based maintenance (CBM) system for drilling risers.