Feasible SCR Configuration from FPSO with Large Motions, by Applying Residual Curvature Methods

2021 ◽  
Author(s):  
Andre Amorim Ramiro ◽  
Adekunle Peter Orimolade ◽  
Daniel Nalliah Karunakaran
Keyword(s):  
Fatigue Life ◽  
Gulf Of Mexico ◽  
Water Depth ◽  
Harsh Environments ◽  
Load Case ◽  
Slight Improvement ◽  
Innovative Solution ◽  
Residual Curvature ◽  
State Of Art ◽  
Installation Time

Abstract This paper describes an alternative and innovative solution to Steel Lazy Wave Risers (SLWR) in order to allow the rigid riser be designed in a free hanging configuration from a floater with large hang off vertical motions. This work demonstrates that the residual curvature method can reduce the stress at the touchdown zone (TDZ) within acceptable limits and improves fatigue life when compared to a Steel Catenary Rigid (SCR). The state-of-art concept eliminates the necessity of buoys in a SLWR concept. Further, there will be saving in installation time, this combined reduces the CAPEX to develop new projects, making it a very attractive solution in recent market scenario. The results for Brazil offshore scenario at Santos Basin and in Gulf of Mexico, in a water depth of 2100m indicate a considerable reduction on the stress at the TDZ within acceptable limits. Fatigue results indicate a slight improvement when compared to a SCR in a free hanging configuration. The fatigue performance for the Gulf of Mexico condition has sufficient fatigue life. However, it has potential margin to be developed in the future and achieve better results. The new concept was evaluated numerically through a comprehensive load case matrix contemplating extreme and fatigue analysis. Results indicated the feasibility of the solution, making it a considerable alternative to replace SLWR in harsh environments.

scholarly journals Fatigue Life of Mooring Lines on External Turret Floating LNG for Different Pretension and Water Depth

2019 ◽  
Vol 30 (1) ◽  
pp. 19
Author(s):  
Norman Mahdar Sabana ◽  
Eko Budi Djatmiko ◽  
Rudi Walujo Prastianto
Keyword(s):  
Fatigue Life ◽  
Water Depth ◽  
Mooring Lines

Wet Tree Semi-Submersible With SCRs for 4,000 ft Water Depth in the Gulf of Mexico

2011 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao ◽  
Sherry Xiang
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Cost Effective ◽  
Integrated System ◽  
Fatigue Performance ◽  
Strength Performance ◽  
Field Development ◽  
Vessel Motion ◽  
Optimum Solution ◽  
Mitigation Methods

This paper presents a design of a deep draft wet tree semi-submersible with steel catenary risers (SCRs) for 4,000 ft water depth in the Gulf of Mexico (GoM). The integrated system of hull, mooring, and SCRs is discussed. The design challenges of SCRs are highlighted and results of SCR strength and fatigue performance are presented. A comparison study on strength performance of various types of risers under the GoM environment criteria is performed. The assessment of extreme strength responses from various riser and hull configurations provide guidelines for the best hull selection. Sour service requirement creates challenges in the fatigue design of the production riser system at such water depth. Integrated mooring and riser design provides an optimum solution. It’s found that the majority of riser fatigue damage at touch down zone is generated by wave loading & resultant vessel motion and vortex induced vessel motion (VIM). Several fatigue mitigation methods are suggested to improve the riser fatigue performance, such as planned vessel repositioning. The conclusion of this study is that deep draft wet tree semi-submersible with SCRs can be a cost effective solution for field development at 4,000 ft water depth in the Gulf of Mexico.

FHS Semi: A Semisubmersible Design for Dry Tree Applications

2009 ◽  
Author(s):  
Alaa M. Mansour
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Time Domain ◽  
Frequency Range ◽  
Integration Technique ◽  
Natural Period ◽  
Ballast Tank ◽  
New Feature ◽  
Fully Coupled

In this paper the performance of a new conceptual semisubmersible design that provides motion response similar to a Spar is investigated. The new invention introduces a new feature which is the Free-Hanging Solid Ballast Tank, hence the name FHS Semi. The use of the free-hanging Solid Ballast Tank (SBT) significantly increases the heave natural period while controlling the heave response in the wave frequency range and, therefore, enables the use of the FHS Semi in dry tree applications. The new design’s quayside integration technique and its interface with the top tensioned risers are presented in this paper. Case study for the new design to support a 32,000 ST payload including 15 Top Tensioned Risers (TTRs) in an ultra-deepwater of 8,000 ft water depth is considered. Frequency domain and fully coupled time-domain hydrodynamic analyses have been performed and numerical results are presented to illustrate the new semisubmersible design response in extreme Gulf of Mexico hurricane events.

A New Quantitative Assessment of Current Profile Clustering Methods for Riser Engineering

2015 ◽  
Author(s):  
Gus Jeans ◽  
Richard Gibson ◽  
Oliver Jones
Keyword(s):  
Gulf Of Mexico ◽  
Fatigue Damage ◽  
Water Depth ◽  
Quantitative Assessment ◽  
Direct Method ◽  
Superior Performance ◽  
Clustering Methods ◽  
Current Profile ◽  
One Year ◽  
Individual Profiles

This paper presents a new quantitative approach of defining current profiles for application to riser fatigue assessment using profile clustering methods. The analysis presented here was undertaken using a one year long deepwater current profile dataset from the Gulf of Mexico. The data included near full water column measurements in 3250m water depth at one hour intervals, providing nearly 9000 individual profiles. Riser fatigue damage for each profile had been previously computed as part of the Worldwide Approximation of Current Profiles (WACUP) joint industry project. The new assessment described in this paper applies clustering methods not considered in WACUP, including the K-Means Algorithm (KMA) and Maximum Dissimilarity Algorithm (MDA). These both demonstrate superior performance compared to a much simpler direct method of characterisation. Features of the KMA and MDA methods are contrasted, within the context of previously published application to ocean wave data.

The underwater contractor: his role and development

1978 ◽  
Vol 290 (1366) ◽  
pp. 153-159
Keyword(s):  
Cost Effectiveness ◽  
Middle East ◽  
Gulf Of Mexico ◽  
North Sea ◽  
Water Depth ◽  
Equipment Maintenance ◽  
Surface Conditions ◽  
Additional Burden ◽  
Exploitation And Exploration ◽  
Maintenance And Inspection

Recovery of hydrocarbons from the seabed has a long history, particularly in the Gulf of Mexico and Middle East. Steps and processes required to extract oil from the seabed are essentially the same as those for recovery on land, but with the additional burden of bridging water depth. The transition to exploitation of North Sea discoveries brought problems not always fully appreciated, the most persistent of which is still the unpredictable and harsh weather and sea conditions. The rate of exploitation and exploration depended upon the work speed in the more favourable surface conditions. Experience and ingenuity have contributed greatly to reducing downtime. However, worldwide moves into greater depths and even less sheltered waters, stretch the suitability and cost-effectiveness of conventional structures and the techniques employed for seabed equipment maintenance and inspection. Consequently, the recently developed concepts for installation and servicing of engineering complexes on the seabed are providing one of the most significant steps towards the goal of year-round operations.

Design Of The COGNAC Platform For 1025 Feet Water Depth, Gulf Of Mexico

1979 ◽  
Author(s):  
G.H. Sterling ◽  
B.E. Cox ◽  
R.M. Warrington
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth

A Study of Hydrocarbon Releases in the Gulf of Mexico, 1996 Thru 2010

2012 ◽  
Author(s):  
Louise Matilde Smith ◽  
John Rogers Smith ◽  
Lauren Pattee ◽  
Julius Langlinais
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Deepwater Horizon ◽  
Activity Level ◽  
Release Point ◽  
Environmental Enforcement ◽  
The Past ◽  
Operational Risks ◽  
Starting Point ◽  
The Face

The events surrounding the Deepwater Horizon (Macondo) disaster have changed the face of deepwater operations. Safety and environmental systems (SEMS) plans and capping or containment capabilities are required to meet current Bureau of Safety and Environmental Enforcement (BSEE) permitting requirements for the Gulf of Mexico (GOM). More generally, industry must identify the operational risks associated with future deepwater operations and specify their plans for responding to those risks, in order to maximize the effectiveness of methods to prevent and respond to potential future releases of hazardous, polluting hydrocarbons. This paper describes a study of public BSEE (previously MMS and BOEMRE) data on incidents involving releases of formation fluids to the environment. The purpose of this study was to provide a factual basis for identifying the operational risk of hydrocarbon releases in offshore operations as a starting point for additional work on identifying opportunities to reduce the frequency, severity, and consequences of such releases, especially for deepwater operations. Incidents reported over the past 15 years were reviewed and organized in a spreadsheet. A total of 90 non-pipeline incidents were identified as including enough description to be useful. Most of these incidents were spills greater than 50 barrels (bbls), but blowouts, fires, and explosions are important and included. To the extent possible, the review determined: the flow path taken from the formation to the point in the well or production system where the fluids were released, the release point, the barriers that were used to reestablish control, and what can these events tell us about potential future deepwater events. It is notable that most of these releases occurred in shelf operations rather than deepwater (water depth ≥ 1,000 ft), which was expected due to the much larger number of wells on the GOM shelf. Nearly two-thirds of the releases happened during active drilling, completion, workover, or well-servicing operations. The remaining events occurred during other operations, particularly production, and include two spills after the wells were plugged and abandoned (P&A’d). The number of blowouts per year was relatively small, varying from 2 to 9 for the 15 year period. The number of blowouts has remained roughly constant despite the recent decrease in the rig activity level. Similarly, the size of most spills was relatively small, if the Macondo event is excluded. Nevertheless, the data gives a factual basis for identifying the kinds of events that could lead to future catastrophes if not prevented or identified and controlled successfully.

An empirical time-depth model for calculating water depth, northwest Gulf of Mexico

1993 ◽  
Vol 13 (4) ◽  
pp. 207-211 ◽  
Author(s):  
D. M. Advocate ◽  
K. C. Hood
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth

The State of Dry-Tree Semi-Submersible Platforms for Deepwater Gulf of Mexico

2014 ◽  
Author(s):  
Ming-Yao Lee ◽  
Jack Zeng ◽  
Philip Poll
Keyword(s):  
Gulf Of Mexico ◽  
Technology Acceptance ◽  
Model Test ◽  
Water Depth ◽  
Technology Development ◽  
Cost Effective ◽  
Test Results ◽  
Scaled Model ◽  
Size Limits ◽  
Long Stroke

The use of semi-submersible platforms has become increasingly popular due to its ability to carry large topsides and the possibility for quayside integration. With recent exploration successes in ultra-deepwater fields of the Gulf of Mexico, major oil and engineering companies are keen to look for a safe, reliable and cost-effective dry-tree option to maximize the value of deepwater field developments. Dry-tree semi-submersible (DTS) emerges as such an option to overcome the water depth and size limits imposed by TLP and Spar, respectively, and enables the platform to carry a large well array and payloads in ultra-deep water. This paper presents the offshore industry’s multi-year efforts to mature two promising semi-submersible platform concepts that can accommodate long-stroke dry-tree risers and have large drilling and production capabilities. Results of technology development and qualification will be highlighted with details on hull performance and hull/riser interfaces. Key structural, mooring and riser analyses and scaled model test results including the long-stroke riser tensioning system will be presented. Remaining challenges that need to be overcome to advance the DTS concepts from “technology acceptance” to “project readiness” will also be discussed.

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