Deepwater studies aimed at flow assurance launched

Two joint industry studies are underway to bring improved flow assurance for all operators of deepwater installations. "At present, both major oil companies and independents are experiencing flow assurance problems for which there are technical resolutions," says Chuck Horn, subsea-deepwater business manager of Paragon Engineering Services, Inc., contractor for the DeepStar project and leader of the studies, undertaken on behalf of DeepStar and in conjunction with the US Minerals Management Service. "Our goal is to get this technical information to all parties in the deepwater market."

"The industry needs feedback of technical knowledge and experience from the field. This information will effectively improve the design and management of flow assurance systems while also providing understanding of remediation capabilities," said Jim Chitwood, a consultant to the DeepStar flow assurance committee.

The studies, titled Flow Assurance Practices/Methods for Deepwater Facilities and Pipeline Blockage Remediation Strategies for Long Offset Subsea Flowlines and Pipelines, will specifically address difficulties associated with long distances, deepwater subsea tieback of oil, and production systems and capabilities for deepwater intervention.

Over the next 12 months, Horn and his team will interview both US Gulf of Mexico and UK North Sea operators to develop case studies of 20 or more projects to uncover data that will translate into more successful deepwater pursuits. Issues to be addressed include: actual case histories involving hydrate and paraffin formation, fluid dynamics analysis, production profiles, engineering/design, operations/maintenance programs, and overall problem-solving efforts, with input from service companies commissioned to correct difficulties.

"The team also seeks to include trends for each case study and to identify potential risk factors associated with increased water depth. Of course, each company's proprietary engineering data will be protected throughout this process," said Horn.

Separately, the flow assurance workshop has identified several new equipment development needs for flow assurance that will help bring a step-change in deepwater development:

Reliable downhole instrumentation—reliable data from the well becomes more critical with increased water depth.

Subsea pig launching systems—refinements for mechanical pigs and alternative systems are needed to facilitate pig reloading operations on single flowline systems with deepwater tiebacks.

Well control umbilicals—replacement of hydraulic control umbilicals with control buoys near the well(s) may provide more dependability and flexibility. DeepStar studies are under way to evaluate associated risk.

Top tension risers and steel catenary risers—industry is gathering comparative data as more installations are made.

Coiled pipe fatigue data—ongoing use of both coiled/reeled line pipe and coiled tubing is expected to provide sufficient data for evaluating possible fatigue failure risk.

Subsea separators—subsea separation is under study by a number of industry groups and is expected to have positive flow assurance impact within a year or two.

Subsea production pumping systems—the need for this equipment increases with each well completion in deeper waters. The first units are planned for installation off Brazil this year and will be watched with interest.

Ultra-deep pipeline intervention or remediation—an array of equipment concepts is in conceptual development, including robotic taping machines and remotely operated vehicles.

Expanded pipelay depth capability—at present, studies indicate the upper limit in pipe diameter is about 24 inches in 10,500 feet of water; smaller diameter pipe can be laid in greater water depths.

The Paragon/DeepStar team is considering a second flow assurance workshop for first quarter 2001. Topics for discussion include: new pipeline insulation materials, chemical developments for wax deposition control, development of pipeline repair technology for pipe-in-pipe lines, and development of a standard oil analysis testing program for deepwater assessment.

Edited by Dev George
Managing Editor, Oil and Gas Online