North Carolina officials will begin exploratory drilling Wednesday to gauge shale gas potential in the southeastern part of the state, an area that remains unassessed for energy capacity.

All three planned drilling sites are on state government property and are intended to measure the energy potential of the Cumberland-Marlboro basin, which runs diagonally through seven North Carolina counties, including an eastern sliver of Johnston County.

The drilling will involve extracting core samples for laboratory analysis, as opposed to drilling for direct evidence of gas or oil. The core samples will be taken from a depth of about 240 feet to 400 feet; the cores will measure 4 inches across and about 30 feet in length.

The first drilling site will be the N.C. Department of Transportation Maintenance Yard in Raeford. The drilling will get underway at 7 a.m. and could last two to five days, said the contractor, Russ Patterson, founder of Sanford-based Patterson Exploration Services.

The state awarded Patterson Exploration a $145,000 contract to take three core samples. The drilling, and subsequent laboratory analysis, will be overseen by the N.C. Geological Survey.

The second drill location, at the N.C. Wildlife Commission’s Fayetteville Fish Hatchery in Cumberland County, could be drilled this week or next week. The third site is on Laurinburg Highway Patrol property in Scotland County.

Patterson said the contract includes an option to drill a fourth site in Scotland County at the N.C. DOT Maintenance yard in Wagram.