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Abstract A soil response framework for use in fatigue assessment of offshore wells and piles is presented. The framework covers clay and sand soil types. It was developed through comprehensive series of physical testing and numerical simulations. It hinges on determination of the unload-reload secant stiffness response of soils degraded under cyclic fatigue loading and reaching a steady-state condition. The framework comprises two calibrated approaches: spring-only and spring-dashpot. The latter is more appropriate when dynamic response of a structure needs to be more accurately determined through for time-domain analysis. Efficacy and validation of the framework are demonstrated through three (3) field monitoring programs involving offshore wells installed in ground conditions ranging from soft clays typically encountered in deepwater to layered sands and clays in shallow waters. Further validation is provided by presenting results from an extensive laboratory testing program involving nine (9) soil samples taken from various geographical locations against the key relationships of the framework. The laboratory tests were conducted in a novel apparatus developed specifically for obtaining soil resistanceโdisplacement relationship for input to fatigue analysis.
A Perspective on the State of Knowledge Regarding Soil-Pipe Interaction for SCR Fatigue Assessments
Clukey, E. C. (Jukes Group) | Aubeny, C. P. (Texas AandM University) | Zakeri, A. (BP America Inc.) | Randolph, M. F. (University of Western Australia) | Sharma, P. P. (Det Norske Veritas) | White, D. J. (University of Western Australia) | Sancio, R. (Geosyntec Consultants Inc.) | Cerkovnik, M. (2HOffshore)
Abstract The paper provides a review of the state of knowledge regarding the impact of soil response in the touchdown point region on Steel Catenary Riser (SCR) fatigue. For almost 20 years the impact of soil-pipe interaction on SCR fatigue has received considerable attention within the offshore geotechnical community. Over this course of time field measurements and a variety of experimental and analytical studies have been performed to determine the soil response necessary to characterize the soil-pipe interaction under long term loading conditions appropriate for fatigue. Little of this work has been integrated into existing codes and standards. This paper will summarize much of the new work to provide better insights on how to address the SCR fatigue problems and to serve as reference for future code modifications.
- Europe (0.93)
- North America > United States > Texas (0.67)
- Overview (0.86)
- Research Report > New Finding (0.46)
- North America > Cuba > Gulf of Mexico (0.89)
- Africa > West Africa (0.89)
- Reservoir Description and Dynamics (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (0.93)
Abstract The paper focuses on the results of full size conductor connector-to-pipe fatigue testing of circumferential weldments, and mitigation techniques to inhibit fatigue failure and to evaluate the level of component life extension. This study utilized a standard conductor connector welded to 559 mm (22 inch) diameter by 25 mm (1 inch) wall thickness X56 line pipe. Resonance fatigue testing was carried out at TWI Limited in Cambridge, England. Standard manufacturing tolerances for pipe ovality, weld joint mismatch, and โflushโ blending of the weld profiles on both the internal and external surfaces were used for each of the fabricated fatigue specimens. All tests specimens were Phased-Array Ultrasonically Tested (PAUT) both before and after fatigue testing, and were run with a relatively low axial mean stress of 10 MPa (1.45 ksi) created by internal water pressure. Results showed at the lower cyclic stress range, 100 MPa (14.5 ksi), that most of the fatigue failures were outside of the connectors, while all of the higher cyclic stress range tests, 150 MPa (21.75 ksi), failed in the conductor connector. A second phase of testing eliminated the stress concentrations from the conductor connector design and welded the connector profile halves together. All phase 2 tests were performed at the higher cyclic stress range, and failed in the X56 piping. Three of the phase 2 tests incorporated mechanical shot peening over the blended internal and external weld surfaces to improve fatigue resistance. All three of these tests also failed in the X56 line pipe material, well outside of the weld area.
- North America > United States (0.46)
- Europe > United Kingdom > England > Cambridgeshire > Cambridge (0.24)
HIPPS-Based No-Burst Design of Flowlines and Risers
Politis, Nikolaos (BP America Inc.) | Banon, Hugh (BP America Inc.) | Curran, Christopher (BP America Inc.)
Summary A methodology is proposed for design of subsea flowlines and risers coupled with a subsea high-integrity pressure protection system (HIPPS) for fields with high shut-in tubing pressure (SITP). The proposed approach uses a design pressure that is lower than the SITP while maintaining a high reliability against burst failure. This approach enables an inherently safer design and ensures that the system integrity is not compromised in the unlikely event that HIPPS valves fail to close upon demand. The proposed design methodology is supported by a combination of analytical and experimental results. Further, an example is provided for demonstration purposes.
This paper describes how the desire for real world data must be matched by an equal determination to use it efficiently and in a timely manner to benefit a facility's operating performance, management of longer term risks, and enhance future projects. The paper addresses how balance between data collection and its use can be achieved through influencing design and operating performance.
THE THUNDER HORSE PROJECT: A NEW BENCHMARK IN THE GULF OF MEXICO
Walker, B. L. (BP America Inc.) | Milburn, Frank (ExxonMobil Development Company Inc.) | Steel, J. M. (BP America Inc.) | Wulf, Gary T. (BP America Inc.) | Erb, Paul R. (BP America Inc.) | Healey, Michael W. (BP America Inc.) | Saha, Lynn E. (BP America Inc.)
Abstract The Thunder Horse Field is located in 6,000 feet (1,800 metres) water depth in the U.S. Gulf of Mexico. Thunder Horse is a giant field that will set new benchmarks with respect to scale, cycle time, and several technical features in the region. General characteristics influencing the development of this deep hightemperature, high-pressure field are outlined. The field development approach, based on subsea completions and a large, permanently moored semisubmersible Production Drilling Quarters (PDQ) platform, is discussed. Environmental conditions in the U.S. Gulf of Mexico are briefly compared with other deepwater development locations. Driving elements in concept selection are then reviewed against that context. An outline discussion of the distinctive design features and related technical challenges is presented for all the major components of the development system. Finally, an overview of the project execution plan for the large semisubmersible production and drilling platform is given. Ongoing contributions of the many members of the Thunder Horse team worldwide are gratefully acknowledged. Introduction The Thunder Horse development is located in the Mississippi Canyon area of the U.S. Gulf of Mexico about 150 miles (240 kilometres) southeast of New Orleans, Louisiana. Water depth in the area ranges from 5,800 to 6,500 feet (1,768 to 1,981 metres). The initial Thunder Horse discovery well (MC778 #1) was completed on July 4, 1999. BP America Inc. holds a 75% working interest in 8 contiguous blocks that make up the greater Thunder Horse development area. ExxonMobil Inc. owns the remaining 25% interest. At the time of this report, 5 exploration and appraisal penetrations have been completed in the field. The partners have announced discoveries that total an estimated 1.5 Billion Barrels of Oil Equivalent (Recoverable). Thunder Horse is, therefore, the largest find in the U.S. Gulf of Mexico, and among the largest deepwater fields yet discovered worldwide. Figure 1 provides a colourful view of the subsurface structures that constitute Thunder Horse. The salt dome is a distinctive feature in the area and can be seen as the light blue-topped extrusion. BLOCK 1 - - FORUM 1 61 THE THUNDER HORSE PROJECT: A NEW BENCHMARK IN THE GULF OF MEXICO Figure 1: Thunder Horse Subsurface Representation Development of Thunder Horse is a significant challenge, in terms of both technology and project execution. Challenges arise from the following distinctive features that characterize the area:Overhanging and abutting salt layers Elongated shape (~12 miles or 19 kilometres in the longest lateral dimension) Deep Drilling (in excess of 25,000 feet or 7,620 metres vertical depth below sea surface) High Temperature and
- North America > United States > Louisiana > Orleans Parish > New Orleans (0.24)
- North America > United States > Gulf of Mexico > Central GOM (0.24)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Mississippi Canyon > Block 822 > Thunder Horse Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Mississippi Canyon > Block 778 > Thunder Horse Field (0.99)