BergerWorld: 2nd Quarter 2007

Although the world has enormous quantities of natural gas, a majority of the recent discoveries are located in isolated areas far from key markets. To transport this environmentally friendly fuel great distances by sea, natural gas must be converted into liquefied natural gas (LNG). LNG is natural gas that has been cooled to -260 慚, changing it from a gas to a liquid 1/600th its original volume. LNG is then transported in specially designed LNG vessels. Upon arriving at its destination, LNG is stored in specially designed tanks and warmed to return to its gaseous state before distribution to users.

Advanced LNG Storage Concept

Large (160,000 cubic meter capacity) LNG storage tanks are needed for both export and import facilities around the globe. For security and safety, the facilities require full-containment tanks that include primary and secondary storage facilities with a full vapor barrier. These storage facilities typically include a nine percent nickel steel primary containment and a concrete secondary containment. Because the cost of nickel has increased dramatically in recent years, and the availability of the material is constrained, costs and delivery schedules have been rapidly rising.

Berger/ABAM (B/A) recently organized a team of LNG storage experts under the Composite Concrete Cryogenic Tank (C?T) Joint Industry Program to develop less costly and more rapid construction methods. The Team began the initial phase of the program, sponsored by three international oil and gas companies and four major contractors, by identifying potential development gaps or flaws in implementing the C?T concept. The results of phase one have been favorable, showing the promise of a 15- to 20-percent reduction in costs and a four- to seven-month shortening of construction schedules.

Floating LNG Terminals

With the current rates for energy near all-time highs, the need to access stranded gas fields (fields with no convenient access to pipelines) has increased significantly. B/A, in association with Mustang Engineering, has undertaken a series of studies involving innovative floating structure technology at a number of gas fields around the globe. The Team evaluated several development options to access and distribute the stranded gas, including the construction of offshore floating liquefaction facilities, fixed offshore facilities with supporting pipeline networks and a near-shore floating LNG plant with an onshore production facility. Costs and schedules for the prototype facilities were prepared to provide owners with appropriate analytical tools to evaluate development options.

LNG Berth Recommissioning

Located on the Chesapeake Bay, the Cove Point, Maryland, LNG terminal was built in the early 1970s to receive, store and process LNG. While the land-based storage and distribution facilities have been in continuous use since commissioning, the berthing facility has been shut down for several years. To meet the increasing demands for LNG, Dominion Transmission, the owners of the facility, initiated the recommissioning of the berths for receiving and unloading larger LNG vessels. Dominion selected Project Technical Liaison Associates, Inc. to evaluate and upgrade the existing berths, ensuring their compliance with new Federal Energy Regulatory Commission (FERC) operational and safety regulations, as well as their ability to accommodate larger LNG vessels.

B/A was retained to assist in the upgrading of the berths. The Team performed several mooring analyses for the larger LNG vessels expected at the facility using the state-of-the-art OPTIMOOR program. After condition assessments and analyses, B/A experts concluded that the existing structures are sufficient to service new operations. The Team then recommended new mooring hardware and minor repairs to the existing fenders and bollards at the berths. B/A also provided procurement and construction support, including preparation of specifications and inspections to assure that the new equipment was properly installed. The terminal is currently one of the largest LNG import facilities in the United States, with a daily send-out capacity of 1 billion cubic feet (BCF) and a storage capacity of 7.8 BCF.

Assisting Offshore Energy Facilities

Glomar Beaufort Sea I and II

In order to do exploratory oil drilling in the Arctic, oil companies are required to construct man-made gravel islands to set up the drilling equipment. When drilling is complete, the islands are dredged up and relocated to another location - an expensive and environmentally adverse procedure. When drilling is required in deeper depths of water, the amount of gravel needed, as well as the resulting sea floor footprint, increases dramatically. To meet the need for drilling in deep waters, Global Marine Company developed the Glomar Beaufort Sea I, a Concrete Island Drilling System (CIDS). The CIDS is composed of a modular concrete "brick" which supports a barge-mounted drilling rig used for oil exploration. The CIDS is towed to a drilling site and ballasted to the bottom with seawater. When drilling operations are completed, the CIDS is deballasted and towed to another drill site. Since gravity load is achieved by ballasting the modules with seawater, dredging and gravel-handling activities are eliminated. Because of its ability to support drilling operations, maneuver in deep waters and withstand extreme ice pressures, the CIDS provides an economically attractive alternative to the single-use gravel islands currently being used.

B/A was commissioned by Global Marine and Exxon to develop and monitor a proactive construction quality assurance plan for the CIDS in Tsu, Japan. The Team's primary tasks included reviewing the construction schedule, developing a practical and effective quality assurance program, and providing design reviews and construction engineering. A comprehensive quality assurance and control manual was prepared to guide overall construction and to ensure compliance with standards set by the American Bureau of Shipping and the U.S. Coast Guard. As project construction activity accelerated, B/A staff served on a top-level troubleshooting team to quickly resolve problems encountered during the complex construction, ensuring the project's cost-efficient and timely completion.

The B/A team was again selected by Global Marine to review the design for the proposed Glomar Beaufort Sea II. The new design took advantage of B/A's experience with composite construction and adopted reliable element connection schemes proven on many past floating structure designs. B/A first recommended a straightforward orthogonal internal bulkhead system to distribute icewall loadings throughout the structure. The composite steel-concrete icewall offers a cost-effective alternative to the original design and has provided lighter and stronger structural members. Additionally, flat precast concrete plates were used for the interior bulkhead construction. This allowed production of the offsite prefabricated precast panels to occur simultaneously with other construction, minimizing activity in the graving dock and accelerating the construction schedule. Finally, B/A evaluated the costs and construction schedule to assure that the design revisions would result in reduced costs and the prompt completion of the Glomar Beaufort Sea II.

Floating Ammonia-Urea Power Plant

B/A was retained by the Swedyard Group to design a series of five football-field-sized floating foundations for a large ammonia-urea processing plant to be transported to Pakistan after off-site prefabrication at a shipyard in Gothenburg, Sweden. The plant was conceived to commercialize onshore natural gas resources in locations where there was no local gas market or pipeline distribution system, creating an exportable product (ammonia-urea) from gas resources that otherwise had no value.

B/A developed a concept using precast concrete haunched flat plates as the basic construction element. The plates were joined using wall-to-wall, cast-in-place joints, a cast-in-place base slab and a topping slab placed over heavy-duty deck planks. The overall structure was post-tensioned to assure water-floating integrity and durability. The modular design and high-load carrying capacity of the various deck elements allowed last-minute revisions as details of equipment loadings and footprints became available. State-of-the-art submersible transport barges were used for open-ocean transport of the units. Platforms were designed for off-loading in moderate sea conditions followed by permanent grounding in a prepared basin at the deployment site. Processing equipment fixings and supports were designed for full open-ocean storm condition forces. The entire facility was checked against the highest earthquake loading possible at the seismically active grounding site. B/A's design took maximum advantage of local construction practices and existing shipyard equipment for the construction of the concrete modules and the installation of the process equipment modules.

The ammonia-urea power plant consists of large deck-mounted equipment and major utility piping and cabling, including reformers and large reactor and pressure vessels. Daily plant production capacity includes 1,350 tons of ammonia, 1,725 tons of urea and 1,750 tons of diammonium phosphate.