Click here to subscribe Make us your homepage
Published November 02, 2012, 12:00 AM

ENERGY: Proppant potential

State geologists examine North Dakota clay formations for use in hydraulic fracturing

By: Kris Bevill, Prairie Business Magazine

The North Dakota State Geological Survey recently completed a mapping project to investigate the potential for clay deposits located in the southwestern part of the state to be mined for the production of ceramic beads used as a proppant in hydraulic fracturing activities. Ceramic proppant is one of two types of proppants currently used in hydraulic fracturing activities in the Bakken region.

State geologist Ed Murphy collected approximately 200 rock samples from 61 sites in two kaolinite-rich geologic formations stretching across an area that includes the cities of Dickinson and Bowman. Collected samples were then analyzed for aluminum oxide content, which is a desired component for proppant material. According to Murphy, clay containing at least 20 percent alumina has the potential for use as a proppant. A small number of initial samples displayed an aluminum oxide content ranging from 26 to 38 percent. The larger sample pool showed to contain lower percentages of aluminum oxide, but Murphy believes the content could still be high enough to be useful. The state’s mapping project will serve to assist interested parties in further exploring the potential resource. “We’ve laid the groundwork for a company to come in and do a more detailed investigation,” he says. “Ultimately, they will need to do some small-scale mining and run that clay back into their plants” to see if it works.

Kaolinite is a clay mineral known for its strength and stability when baked, properties which are beneficial to hydraulic fracturing applications. According to Murphy, proppants are named as such because, when injected along with hydraulic fracturing fluid, they serve to “prop open” cracks in the rock, preventing those cracks from sealing shut. Kaolinite is also used to manufacture bricks. North Dakota’s only brick manufacturer, Hebron Brick Co., currently mines one of the state’s kaolin-rich formations for its operations.

The North Dakota Geological Survey estimates there are 1.7 billion tons of economically mineable kaolin in the state. Because companies working in the Bakken region currently use ceramic proppant, natural white sand proppant, or a combination of the two, it is difficult to estimate the current rate of ceramic proppant usage in the area. However, Murphy says a typical Bakken oil well uses between 3 million to 5 million pounds of proppant. By the end of 2012, an estimated 2,400 oil wells will be completed in North Dakota, requiring roughly 5 million tons of proppant. Most of the natural white sand used in Bakken wells originates from Wisconsin and Illinois, while the majority of ceramic proppant is imported from China. Hydraulic fracturing is a significant expense associated with oil production in the Bakken, accounting for about a quarter of the total $9 million to $11 million spent to complete each well, according to Murphy. He says the kaolin formations could help reduce those costs and prove to be a significant resource for the state.

Land explored for the mapping project varies in use, but the majority is pastureland. Owners of the clay material can vary depending on the terms of each mineral deed, so each deed would need to be examined to determine if the surface owner or mineral rights owner controls that resource, Murphy says.

A full report of the state’s findings, including clay mineralogy conducted by researchers at North Dakota State University’s Center for Nanoscale Science and Engineering Laboratory, is expected to be published by the end of this year. According to Murphy, the main goal is to provide answers to industry questions in advance. “If a dozen companies come in to investigate the potential for these clays for ceramic proppant they would all have to do the first three or four steps that we’ve done,” he says. “Now they can pick up this report and go from there.” PB

Kris Bevill

Editor, Prairie Business