Research reveals best well site reclamation practices

By Staff | October 02, 2017

Jay Norton, an associate professor at the University of Wyoming and director of the university’s Soil Resource Laboratory, spent seven years studying reclamation on three gas well pads in different areas of Wyoming.

He will present the results of his research on Oct. 23 at the Managing Global Resources for a Secure Future annual meeting in Tampa, Florida. The event is sponsored by the American Society of Agronomy, Crop Science Society of America and the Soil Science Society of America.

“Soil Changes Before, During, and After Natural Gas Drilling” is the title of the paper Norton coauthored with Calvin Strom, University of Wyoming, Laramie, and Emad Aboukila, natural resources and agricultural engineering, Damanhour University, Damanhour, Egypt. Norton discussed the results of the study with North American Shale Magazine.

What are the issues with well site reclamation that your research covers?

There are questions about topsoil management—especially on these difficult, arid sites—and how to get a desirable plant community reestablished. There are some real challenges with saline and sodic soils. In arid areas, there’s usually a thin topsoil layer (A horizon) that’s desirable for plant germination and establishment. And then there’s a more saline or sodic subsoil two or three inches down—or less even—of undisturbed soil. What happens when the salvaged topsoil is mixed with more saline or sodic subsoil and, often times, finer textured clay is that you get a fine-textured saline or sodic soil that crusts over really bad. Then it’s really hard to get native plants reestablished.

Where were the wells that you studied located in Wyoming?

For this study, we looked at three well pads in each of three different well fields in the Wamsutter area, the Jonah Field and the Pinedale Anticline. They’re along a gradient of lower precipitation. The anticline has more precipitation and is a little more forgiving. We tracked this for two years, skipped about five years and then resampled everything last year. We tracked it over seven years total.

What did your research show that could be done differently or better to improve well site reclamation?

One of the real takeaways for me was just how important the weather is. Back when we started in 2009 and 2011, we had a series of dry years. Reclamation operators were wringing their hands about how to get anything going because very little would grow out there. But then we got a series of wetter years in 2013, 2014, 2015 and 2016 that were pretty moist for the sites in the fall and a little above average all year. Fall precip can be especially important for those native species. That was a huge factor in the recovery of the vegetation that we saw when we went back seven years after the initial disturbance and also in the recovery of soil organic matter. Sometimes we just need to be patient and wait for some rain. We forget how variable these semi-arid climates are with respect to rainfall to the point of being unpredictable.

What you saw in the soil wasn’t the result of drilling activity?

No, I haven’t dealt with anything like that. These were just sites where the topsoil was salvaged and stockpiled to a depth of 15 centimeters (about 6 inches). The well was drilled and then they went through interim reclamation. During the production phase of the well, the site is partially reclaimed. When the well’s closed, then they go in and do final reclamation. We’re looking at interim reclamation where they leave road access to an area. We started sampling a year before the development. They salvaged the soil, stockpiled it and reclaimed the site within a year.

For companies involved in well site reclamation, what do you consider the most important results of your research?

On these arid sites, I think a couple things are really important. The first is to salvage the soil as shallow as possible. If you can salvage two or three inches instead of six inches, generally that’s as thick as the A horizon is going to be. You need to do a salvage-depth inventory so that you know how deep to salvage. If you go below two or three inches, you’re into soil that makes undesirable growth medium for desirable vegetation. The other thing is to minimize the disturbance. We’ve found that if you salvage and stockpile, that’s a pretty major disturbance. Reapplying that soil is another major disturbance. With each major disturbance, you’re losing a lot of organic material by stimulating decomposition. You need to avoid moving stockpiles around because every time you do that, you’re reintroducing oxygen and stimulating the loss of organic material in the soil. The organic material in that surface soil is really important for maintaining infiltration and water- and nutrient-holding capacity.