Offshore in depth

I spent two days in September at the Ultra Deepwater Technology Conference in Houston, hosted by Research Partnership for Secure Energy in America
(RPSEA). During the conference, engineers and scientists from industry, government and academia presented interim reports on research projects that are funded jointly by the U.S. Department of Energy (DOE) and private industry partners.

Programs are managed by the DOE’s National Energy Technology Laboratory (NETL). RPSEA President James Pappas noted that the solution to most deepwater challenges can be found through good science, transparency and the sharing of information.

Subsea measurement technology. Several presentations discussed the feasibility, design, or prototype testing of equipment and structures to be used in deepwater exploration and development. For example, Chip Letton of the Letton-Hall Group described an ROV-compatible, fluid-sampling prototype; a live production stream sensor scheduled to be tested at NASA’s neutral buoyancy lab; clamp-on flow meters designed to be attached to electromagnetic-transparent carbon fiber pipe sections on subsea installations; and an early kick detection system based on a sensor package placed just above the BOP. These projects are being carried out with involvement by experts at operators and service companies, and their rapid progress has been the result of “attacking these problems in a concerted way,” Letton pointed out.

Chemical storage on the ocean floor. Art Schroeder, of Safe Marine Transfer LLC, presented the concept of deploying a 3,000-bbl subsea storage reservoir to provide production chemicals for subsea fields, simplifying logistics and eliminating the need for tote tanks or chemical umbilicals. The storage reservoir would be mounted on a submersible barge and towed to location by two low-cost supply boats. Ballast tanks on the barge would be filled with seawater, and tow-lines connected to the supply boats would control the barge’s descent to the sea floor. Chemical flowlines would be connected to subsea wells using ROVs.

The pressure-compensated bladder (or bladders) on the barge could supply three to six months of methanol or other chemicals, depending on the number of wells served. Once empty, the whole system can be retrieved to the surface. Schroeder pointed out that this deployment and retrieval concept can be applied to supply dispersant for spill response, or to enable surface maintenance of complex subsea equipment, like multiphase pumps.

Nano-seismic surveys. A project conducted by Paulsson, Inc., Fluidion and Southwestern Energy has demonstrated the ability to introduce tiny seismic sources into frac fluid while using fiber-optic sensors to detect the nano-seismic events from a parallel monitoring well. Hollow plastic chips from Fluidion are pumped with the proppant and collapse during the stimulation treatment, creating sounds that give a direct measurement of the extent of the fractures. The dual-fiber measurement system is deployed on special drill pipe and detects the seismic events. The system can sense data at intervals as small as 3 ft, and the biggest challenge may be processing all the acquired data, which is already a limitation of more conventional microseismic services.

Waves and currents. Grant Stuart of Fugro Environmental and Ocean Sciences, Inc., discussed projects aimed at measuring currents on the ocean floor and the surface of the Gulf of Mexico. Computer modeling and sensor buoys tethered to the seabed showed that local currents vary tremendously, based on subsea topography and other factors, which should be taken into account as engineers design subsea pipelines and production facilities. Stuart also presented preliminary results of a project that used aerial photographs of wave action to calculate the speed and direction of near-surface currents. The method could, ultimately, be used to forecast wave action and currents ahead of approaching hurricanes.

Metaocean studies. Big data comes into play in Metocean studies, combining meterology and oceanography, when analyzing ocean temperatures, wave patterns, and climate change, in an effort to predict the frequency, intensity and impact of hurricanes. Cindy Bruyere, of the University Corporation of Atmospheric Research, presented results of extensive modeling and statistical tools, studying atmospheric and ocean effects, and loop currents, in the Gulf of Mexico and globally. These studies involved more than 500 terabytes of data, including 250 years of past data and 150 years of projected data. Analysis indicates that while the frequency of hurricanes probably won’t increase in the future, their intensity and damage potential are likely to grow.

NETL’s important contribution. Ray Long of NETL described the laboratory’s role in developing cooperative agreements between government, industry and universities, and in providing financial assistance to conduct research to advance energy development in the U.S. Before the Macondo accident, most NETL projects were aimed at improving recovery and operating efficiency. After the 2010 blowout, NETL’s priorities shifted to process safety, geologic uncertainty, and controlling risk during drilling, completion and subsea production.

Much of NETL’s budget under the Section 999 fossil energy program (which also supports unconventional and EOR technology development) will expire at the end of September 2016. It remains to be seen whether Congress will continue to fund its projects in FY 2017. Let’s hope that our elected representatives come to their senses to renew support for NETL and RPSEA. As Chip Letton remarked during the conference, “RPSEA projects have been of great value to everyone involved, and to the industry in general.”

About the Authors

Ron Bitto

Contributing Editor

Ron Bitto has more than 30 years of experience as a technology marketer and writer in the upstream oil and gas industry. RON.BITTO@GMAIL.COM