State team investigates Umiat area

In late July and early August a crew of geologists led by Marwan Wartes from Alaska’s Division of Geological & Geophysical Surveys and the state’s Division of Oil and Gas conducted some fieldwork in the area of the Umiat oil field and the Gubik gas field, on the central North Slope , DGGS geologist Dave LePain told Petroleum News Nov. 14. The geologists were doing some detailed bedrock mapping as part of a multiyear program of geologic research along a swathe of territory on the north side of the Brooks Range, gaining new insights into the petroleum systems of the North Slope.

Interest in the Umiat/Gubik area has been heightened by a state proposal to build a resource-access road west from the North Slope Haul Road to Umiat, LePain said. The current field program in the area started in 2010, although a DGGS-led team had previously worked in the Umiat area in the early 2000s. This year’s field program was primarily funded by the state, with some funding assistance from industry, LePain said.

Surface rock exposures in the area are quite limited, and the team has been working its way around all of the available exposures, measuring the orientations of the rocks, measuring stratigraphic sections along the rock exposures and taking rock samples for analysis. The idea is to gain a better understanding of potential oil reservoirs, as well as to better understand the ways in which the strata are faulted and folded, LePain said. Among other things, the state scientists want to elucidate how the style of the faulting and folding may affect reservoir effectiveness, he said.

The team anticipates completing the bedrock mapping next year. During this year’s fieldwork the team found a small oil seep and oil sheen, on the Colville River just south of Umiat Mountain, LePain said. That seep probably relates to the oil pool of a known oil field at Umiat, he said. Linc Energy is planning to drill some delineation wells in the Umiat field this winter.

—Alan Bailey