Technology Development & Solutions
addition to the mono hull, three floating structure designs ─ TLP,
Semi, and Spar ─ have been successfully developed over
the past several decades. Each of these floater designs has
been evolving along with subsea and riser technology to meet
new field development challenges mainly related to increased
water depth and reservoir operating pressures and temperatures. Design
improvements continue as new developments in offshore technology
are incorporated into the basic designs
The functional requirements for
floating structures can be generalized as;
- Drilling facilities
- Number, type and location of drilling rigs
- Production facilities
- Weight, area and center of gravity
- Drilling/ production risers
- Well systems
- Number of wells, completion and workover methods
minimum well spacing and well bay location
- Hull compartmentsation
- Damage stability considerations
- Air gap requirements
As illustrated in the figure below, the relative hull responses
of the three designs vary considerably. In all cases the
objective is to minimize the response to the environment.
Efficient design of floating structures
is predicated on functionality and performance – it should be capable
of supporting all the necessary equipment for production
and related tasks while meeting all performance criteria.
The structure should provide sufficient space and robustness
to fulfill its intended purpose ,. Also, the floating structure
should be built at a minimum of cost, which is governed mainly
by the hull steel weight.
Hull weight estimates are based on global sizing which is
determined by the naval architectural and structural design.
Global sizing is a key engineering design process in both
the concept selection stage and design phase of a floating
structure. The sizing of a moored floating structure considers
relationships among the payload, the size of the hull, and
the mooring system. During the concept selection phase, efforts
are concentrated on the main dimensions and weights under
the consideration of design standards and performance requirements
without a high degree of engineering detail. Finalized dimensions
and main properties of the floating structures will be determined
in the front-end engineering and design (FEED) stage through
FloaTEC, LLC was formed specifically to provide unbiased
and concept-neutral engineering to support the deepwater
industry. It is unique in that it is the only company that
can offer and deliver a suite of multiple hull forms (TLP,
Spar, and Semi), including moorings and risers from technical
feasibility work to an EPC delivery. FloaTEC, LLC’s
objectivity relative to floating production platform concepts – along
with the worldwide experience and support from the McDermott and
KFELS organizations - means the company is ideally suited
to participate in front end study and technical feasibility
work. It also enables FloaTEC, LLC to employ innovative construction
engineering techniques and provide a high level of confidence
in project estimating and project execution planning. Also,
in dialogue with its clients, FloaTEC, LLC is prepared to
engage in some innovative contracting and delivery models
encompassing EPC strategies as well.
FloaTEC, LLC will spend a great deal of
energy further developing their portfolio of floater designs,
particularly the semi. When one looks at the maturity of platform
designs, the spar is in its fourth generation, the TLP is in
its fifth generation, but for the production semi, the industry
has only scratched the surface. That is the area where FloaTEC,
LLC and its parents will put a lot of effort initially to bring
it up to par with the others - including model testing, motion
analysis and riser issues. The group will focus on creating
a semi design that is applicable for a variety of deepwater
projects – for
both wet tree and dry tree applications. Instead of trying
to come up with multiple semi designs that play to the entire
spectrum, FloaTEC, LLC’s objective will be to find the
sweet spot relative to water depth, payload, and riser issues.
Dry Tree Semi-submersible Technology Development
FloaTEC, LLC has two dry tree semi solutions in its Truss Semi (T-Semi) and Extended Semi (E-Semi) designs, as illustrated below. The designs draw on strengths of FloaTEC, LLC parent companies Keppel FELS and McDermott.
The difference between them is the method of the means to suppress heave. Both use the same basic deep draft hull design. One version employs a single extendable heave plate, while the other employs a truss section with multiple heave plates.
Both concepts have been through initial model testing, and FloaTEC, LLC is moving forward with further testing in 2009, with the objective of commercializing the technology later this year. It is important to note that this is not new technology. FloaTEC, LLC is simply marrying existing technology to add value and create a hybrid to enable dry tree production and direct vertical access into the wellbore.
Both solutions utilize versions of the FloaTEC, LLC proprietary semi-submersible hull design with a deep draft and rely on hydrodynamic interaction between the heave plate and the hull to reduce motions. With the E-Semi, the heave plate is installed under the hull as part of the hull construction, so at location the heave plate is lowered into final position. For the T-Semi, the truss would be launched like a conventional jacket and mated with the hull either near shore or offshore. The E-Semi offers slightly more flexibility in terms of redeployment, while the truss semi is probably more suited for a permanent installation.
It is significant to note that the motions are limited to enable the use of commercially available tensioners, currently limited to under 30ft stroke. Longer stroke tensioners beyond 30ft would require more real estate to accommodate and are currently not commercially available. Not to mention that they would also be prohibitively expensive. FloaTEC, LLC is developing base case designs of the dry tree semi for Gulf of Mexico conditions for two different water depths - 4,300 ft and 8,000 ft.
FloaTEC, LLC believes the industry will like not only the ability to quayside integrate the platform, but the flexibility that comes with the well bay design of the dry tree semi as well. There are efficiencies in both well bay and deck layout, thus resulting in more efficient drilling and production operations.
FloaTEC, LLC offers both T-Semi and E-Semi to field developers who are looking to capture all the advantages of dry tree drilling and production and direct vertical access to the wellbore; which of the two solutions is ultimately selected for the field development will depend on operator preference and the metocean and marine/installation vessel availability in the area.
FloaTEC R&D Initiatives
FloaTEC, LLC has a core technology R&D group of specialists in hull and mooring performance, riser design and analysis and offshore structure design and analysis. Most members of the research group hold a PhD in their respective fields of expertise and have varying degrees of experience from one to 20 years. The base R&D activities are aimed at developing tools and techniques that provide accurate sizes and related quantities of the three products, the Extended Tension Leg Platform (ETLP)®, the Truss Spar, and the Semi-submersible with deep draft (DDS).
In addition to these products, FloaTEC, LLC is engaged in other R&D efforts including the development of a dry tree semi (as outlined above), extending the operating depth of the ETLP® to 7,000 ft, developing tensioning systems for risers in ultra deep water and designing hull architecture to decrease fabricated steel weights and increase payload.
The R&D focus areas and related efforts are:
Tool enhancement is an ongoing effort focused on identifying new and alternative methods that advance the design and analysis tools to support our products. These include continued development of a fully coupled model for all floater designs, including hull, risers and moorings. Specialized computer models for individual hulls, risers and mooring and tendon systems are also considered.
Product portfolio Maturity and Performance Enhancement
Dry centerwell involves the technical evaluation of using a dry centerwell in a Truss Spar hull. The basic idea is to utilize the void in the centerwell to provide buoyancy to the hull. The result is an increased payload for a smaller hull diameter, a saving in hull steel to support the same payload as compared to a conventional open well and, because of the smaller hull diameter, a reduction in the size of the mooring system. The scope of work included hull sizing, performance evaluation and delivery model.
The Dry Tree Semi is a concept under development as an alternative deep water dry tree concept.
The ETLP® has a R&D program to extend its operating depth to 7,000 ft. At present the deepest TLP design is the Magnolia in 4,700 ft. This is a FloaTEC ETLP® design. The main focus in the effort is the tendon length required for operation in this water depth. Two patented designs for the extension of these tendons for this water depth are under investigation. Following structural analysis and assessment, physical model tests are planned to evaluate the predicted performance.
Portfolio of Solutions
Under the FloaTEC, LLC umbrella,
the joint venture boasts an unmatched portfolio of
three floating production solutions for its clients,
represented by their brand names – SparTEC®;
SemiTEC™ and TlpTEC™. FloaTEC, LLC’s
objectivity relative to floating production platform
concepts – along with the worldwide experience
and support from the McDermott and KFELS organizations - means
the company is ideally suited to participate in front
end study and technical feasibility work. The company was formed specifically
to provide unbiased and concept-neutral engineering to
support the industry. FloaTEC, LLC is unique in that
it is the only company that can offer and deliver a suite
of three distinctly different hull forms (TLP, Spar,
and Semi), including moorings and risers from technical
feasibility work to delivery of an EPC contract. Click
here for our Portfolio of Solutions PDF Document.
Scope of Services:
• Technical Feasibility Studies
• Unbiased Concept Screening Studies
• Front-End Engineering and Design (FEED)
• Detailed Engineering Design
• Engineer, Procure, and Construct (EPC)
• Engineer, Procure, Construct and Install (EPCI)
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