Advanced Technology

Petrobras testing drilling, production, marine systems this summer

A one mile-long flight runway suspended on a continuous semisubmersible pontoon framework has been designed by Kvaerner Maritime and Boeing for the US Office of Naval Research and the two have been awarded a feasibility study on the structure. The $5 billion structure, complete with flight facilites, airplane storage, and flight crew and troop quartering can be sectioned and transported around the world.

Petrobras is preparing to deploy or test a number of technical solutions to more efficiently and less expensively develop deepwater fields:

Multiphase pump: Petrobras and Westinghouse are conducting runs at the Atalaia test site of the subsea pump. The unit features a Leistritz multiphase twin-screw pump and Westinghouse motor driver to move as much as 75,000 b/d of liquids and gas from depths exceeding 3,000 ft. The system will be deployed on Marlim in 1998.
Multiphase flow meter: Petrobras and Fluenta begin tests on a new meter next month, with deployment on an Albacora field well later this year.
Differential compliance mooring: The system is spread mooring with partial weathervaning for floating production tankers with differential stiffness at the bow and stern. The system eliminates a costly turret and is ideal for areas with prevailing wind, wave, and current conditions.
Steel catenary riser: As an option to costly flexible flowlines, Petrobras plans to install a test 10-in. steel catenary riser this summer on the P-18 semisubmersible to better understand riser behavior.
Taut leg mooring: Petrobras will replace all conventional catenary mooring systems with taut leg systems, beginning on Bijupira-Salema next month.
Suction piles: Petrobras intends to install several test systems at the end of this year as a complementary to other new mooring components.
Multilateral wells: In an effort to reduce well numbers, Petrobras is planning to drill and complete multilateral wells on the South Marlim and East Albacora fields, beginning in 1999.
Extended reach wells: Petrobras hopes to push the lateral reach of displacement wells out to 5,000 meters on the South Marlim field. The longer extensions are planned for 1999.
Deepwater shallow reservoirs: Petrobras is developing new well stability and control equipment and techniques to tackle a number of reservoirs in very deep water that lie only 700-1,000 meters below the mudline. Most of these are on South Marlim and development will begin in 1998.
Slimhole drilling: Petrobras sees slimhole drilling as the solution to drilling in very deep water and has scheduled a number of wells with slimhole equipment in 1999.

Researchers study manufacture of seabed gas hydrates

Researchers at Texas A&M's Geochem-ical and Environmental Research Group are testing various ways of converting natural gas escaping from the seafloor into gas hydrates, storing it in blimb-like containers, and towing the containers to shoreline plants for re-gasification and pipelining to consumers. One cu ft of gas hydrate contains about 164 cu ft of free gas.

Roger Sassen and Ian MacDonald have developed a quick method of creating the gas hydrates and are investigating methods of trapping natural gas escaping from seafloor fissures. Currently, gas is being trapped offshore California with large square funnels and piped ashore, but the effluent is transported in gaseous form. The environmental effects of such endeavors are significant, since the natural gas escaping from the seafloor enters the atmosphere and turns into a greenhouse gas.

Trials completed on electron beam, diffusion pipe welding systems

Successful trials have been completed in recent months on two welding systems for pipelines:

An electron beam system that is ideal for single-station J-Lay pipelaying systems has been tested off Italy. Electron beam systems, developed by The Welding Institute in Cambridge, England, can completely weld pipe girths up to 1 in. in wall thickness with one pass, unlike other systems that require 3-5 welding passes and multiple welding stations. The vertical arrangement of J-Lay systems permits only one station and is ideal for electron beam.
The drawback to electron beam is the 1 millibar vaccuum required. The vaccuum conditions were successfully completed for the most part and an assessment of the weld fusion quality and number of defects is underway. A prototype portable system was used. The development was funded by the European Union.
A diffusion welding process developed by Napan National Oil Corporation allows quick joining of lengths of alloyed seamless tubing. The process developes a liquid bonding between the base metal and filler metal at less than the melting point of steel. Diffusion welding retains the fatigue properties of the base metal and allows the joining of normally difficult-to-weld alloys. The filler metal completely diffues into the base metal leaving a joint that resembles a smooth base metal appearance.

Virtual reality system developed for projects

A program to model and display facilities and plants in real time before they are constructed has been developed by Bechtel Research & Development of San Francisco. The systems have been deployed on downstream plants onshore and are being modified for upstream oil and gas facilities. The system combines advanced visualization and virtual reality on 3D computer-aided design systems. In effect, the process allows a producer to walk through a photo realistic similation of a facility and anticipate problems before final design.