Global Petroleum Research Institute to compare technologies in Marcellus Shale

BY ERIC LIDJI FOR GREENING OF OIL

Extracting natural gas and oil from shale requires large amounts of fresh water for both drilling the deep wells and hydraulically fracturing the rock to release the gas and liquids, making shale development troublesome for some communities. A cheap and efficient way to reuse the water could ease those concerns.

To that end, a pilot test begins this month that will compare various methods for treating produced water in the field.

The test, headed up by the Global Petroleum Research Institute at Texas A&M University and involving several other partners, is being funded by the National Energy Technology Laboratory, or NETL.

The partners aim to develop a mobile technology for pre-treating used water. The pilot tests will focus on the Marcellus Shale in New York, Pennsylvania and West Virginia.

Pre-treatment commonly involves removing certain substances, like chemicals and metals, from industrial wastewater before treatment in a municipal water facility, where water is normally brought to drinking water standards.

But for shale development, the normal pre-treatment process is enough to allow much of the water to be reused.

“What we’re doing in the oil field is trying to do that (pre-treatment) on a smaller scale and do it with more precision,” said David Burnett, director of technology at the GPRI at Texas A&M.

Some recycling techniques already exist. In recent years, the Railroad Commission of Texas approved several pilot projects for entrepreneurs to test different technologies for reducing water use in the Barnett Shale that runs across North Texas.

Growing need for domestic oil and gas supplies

The push to improve the technology, though, is becoming more and more important because North America’s prolific shale basins could significantly improve domestic oil and gas production.

And despite the fact that natural gas from shale uses the least amount of water of any other fossil fuel, and a fraction of the water required to produce corn-based ethanol and soy-based biodiesel, the perception that shale development is a comparatively water-intensive affair is causing public relations problems for shale producers. (Shale oil development ranks higher in water use, falling between coal and tar sands, but still requires only a fraction of the water per unit of power that is needed by corn ethanol and soy diesel.)

The main water hog in shale production is hydraulic fracturing.

In shale formations, tight rocks trap oil or gas. To increase permeability, drillers pump large amounts of chemical-laced water and sand underground to crack rock formations and prop open the fissures, allowing the oil or gas to move up to the surface.

In the Barnett Shale stretching over North Texas, fracing a vertical well can require 1.2 million gallons of water, according to recent estimates from the Railroad Commission of Texas. Horizontal wells increase the demand, requiring closer to 3.5 million gallons each.

An average hydraulic fracturing treatment in the Marcellus Shale uses about 3 million gallons of water.

Droughts have stressed freshwater supplies

This need for fresh water isn’t just a problem in the dry counties of North Texas, but also for states in the Appalachian Basin, home to the prolific Marcellus Shale.

“While supplies are relatively plentiful in ‘normal’ years, the fact is that recurrent droughts have resulted in sometimes painful shortage conditions affecting, to various degrees, the region’s streams and groundwater aquifers, leading to sometimes heated controversy, conflict and litigation,” R. Timothy Weston with the law firm K&L Gates and a former assistant attorney general for the Pennsylvania Department of Environmental Resources wrote in a May 2009 look at water use in the Marcellus Shale.

Wastewater disposal also a challenge

And the problem isn’t just finding new freshwater for shale development, but disposing of old water.

During production, water rises to the surface along with oil or gas, picking up additional metals and saline underground to create very salty and metallic brine.

Traditionally, produced water is re-injected underground, into deep disposal wells below the water table. This becomes difficult in more populous areas.

All the water being used for resource extraction is water that can’t be used for other things, a problem in parts of the country with limited water resources. Plus, some people worry that the use of fracturing can damage drinking water supplies in residential areas.

For the pilot study, Burnett told his team: “Let’s try to make seawater,” which would allow the water to be reused for fracturing.

Added funds for community education

The goal of the pilot study, Burnett said, is to test technologies on multiple fronts: How efficiently does each one work? How much energy and labor does each require? How many chemicals does each need to pull metals and other substance from the wastewater?

“It’s my intent to try and document that for a number of different technologies,” he said.

The Global Petroleum Research Institute at Texas A&M is part of an alliance with the Houston Advanced Research Center and other university and government players—many of which are partners in the pilot test—that work together to develop technologies that reduce the impact of drilling.

In the past, the GPRI has used membrane technologies to desalinate produced water, but Burnett said that one advantage of using university resources to approach the problem is that, “We’re testing techniques. We’re not wedded to any particular technique.”

NETL contributed $466,665 to the study, which runs through Sept. 30, 2011.

The partners added $450,000. Burnett said the additional money will go in part toward an aspect of the project he considers crucial, but is not funded by NETL: working with the public, with elected officials, and with regulatory agencies “to show clearly why and how their concerns about the safety of their freshwater resources are being addressed.”

Links of interest

Global Petroleum Research Institute

National Energy Technology Laboratory

Railroad Commission of Texas

Contact Eric Lidji at ericlidji@mac.com