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Arctic and fuid fow. Using analogues such optimized for measuring oil under sea ice as the Mid-Norway shelf to deepwater with antennae designed to increase the transition can aid safe drilling within the directionality of the transmitted signal.

Labrador basin. Signifcant discoveries The GPR project focused on the can be made in these deepwater settings, development of new hardware for higher- including the deep-sea Nise formation powered, directional radar systems that fan reservoirs. can be tested in arctic feld environments

The Nise formation consists of deep-sea using light helicopters. The goal of the fan deposits that are combined locally so project was to expand the operating win- that overpressures in the aquifer are the dow for oil detection with GPR, to cover same or similar, and are considered to a wider range of sea ice and climate con- form part of the hydrodynamic system, ditions, extending to thicker and warmer despite the deep burial depth. In more ice sheets in late winter.

stratigraphically-isolated areas of the fans, Tests done on crude oil spilled overpressures can be similar to the encas- underneath an artifcially-grown 92cm- ing shale pressures. thick ice sheet at

These differential pres- the US Army Cold sures, similar to deep- Regions Environmental water complexes found Laboratory (CRREL) in in the Labrador region, New Hampshire, and enhance seal capacity over natural sea ice and create opportunities ranging between 1.7-2m for hydrodynamic trap- thick off Prudhoe Bay, ping—reducing hydro- revealed weak currents carbon permeability within the underlying to near zero. The Base water body can pro-

Tertiary Ormen Lange duce strong anisotropy reservoir is hydrody- in the sea ice crystal namic, with a tilted contact, affecting structure. Containment skirts inserted estimates of reserves and development of during ice growth appeared to alter water the feld. circulation patterns. Similar effects were

Mud weights in several Labrador Shelf also experienced in natural sea ice and wells are low, but there are instances were noted for utilization in future radar of high kicks taken, suggesting that the design and operation.

pore pressure regime was misunderstood Following completion of the radar and the wells may have been drilled surveys, CRREL personnel recorded the underbalanced. Many basins in Eastern temperature and salinity of the ice, ice

Canada, such as Jeanne d’Arc, Flemish thickness, oil thickness, and the distri-

Pass, and Orphan, are similarly associ- bution of oil through a series of cores ated with kicks. This approach could and drill holes. When a hole was drilled possibly be used in the Labrador basins completely through the sample sheet of to give an indication of shale pres- ice, it was possible to detect the bottom sures, based on picking the seismic Base of the parent ice (at the time of the spill),

Tertiary refector. and the top of the new ice layer, which measured the depth of the oil layer. This

Oil Spill Detection Under Sea Ice made it possible to distinguish between

Arctic freshwater ecosystems’ rapid drill holes encountering oil and drill response to climate changes, over the last holes that did not.

50 years, has caused thinning of lakes According to a report from the CRREL, and rivers during seasonal ice cover. the utility of the system could be

This increases winter-water supply for improved by developing a third proto- industrial withdrawal, and permafrost type based on what was learned from the degradation. trials. Increasing oscillator frequencies

The radar development team at Boise and reducing levels at critical mixers will

Stand: F62

State University (BSU) custom-designed both increase the order of the spurious a ground penetrating radar (GPR) system products, reduce their magnitude—which of a higher grade than the commercial will move them further from frequency products currently available. The new and amplitude regions that could result system operates in a frequency range in false responses. oedigital.com December 2013 | OE 59 058_OE1213_Arctic1.indd 59 11/24/13 1:35 PM