A Water Drop on a Journey - Shale Gas Drilling in the Mid-Atlantic
- Jennifer Fetter - Renewable Natural Resources, Penn State Extension
- Joy Drohan - freelance science writer and editor
- Sanford Smith - Department of Ecosystem Science and Management, Penn State
- Charles Abdalla - Department of Agricultural Economics, Sociology, and Education, Penn State
- David Yoxtheimer - Earth & Mineral Sciences, Penn State
- Brian Benham, Virginia Tech
- James Clark, Penn State Extension
- Alan Collins, West Virginia University
- Corrie Cotton, University Of Maryland Eastern Shore
- Deb Grantham, Cornell University
- Dennis McIntosh, Delaware State University
- David Messersmith, Penn State Extension
- Brian Rahm, Cornell University
This material is based on work supported in part by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under Agreement No. 2008-51130-19500.
The Mid-Atlantic Water Program is a coordinated effort among Delaware State University; University of Delaware; University of the District of Columbia; University of Maryland; University of Maryland, Eastern Shore; Penn State; Virginia State University; Virginia Tech; and West Virginia University.
(loud bumping) (mouse clicking)
- [Jennifer] A Water Drop on a Journey.
Shale Gas Drilling in the Mid-Atlantic.
Perhaps you have heard, that new advancements in technology, such as horizontal drilling, and hydraulic fracturing, have been developed, to drill for oil, and natural gas, which can be burned, for heating, making electricity, fueling factories, and running vehicles.
In several regions of the United States, this has caused oil and natural gas drilling to become a booming industry.
In the northeast United States, this is happening, mostly, in Pennsylvania, Ohio, and West Virginia.
Conversations, about shale gas drilling, are also taking place, in Maryland, and New York.
There are debates, about the pros and cons of this industry.
The debates address important issues, such as the economy, energy use, and the environment.
Sometimes, these debates involve the role of water, in the natural gas drilling industry.
This presentation will focus on that important topic.
Let's start, with a basic review of these advancements, in drilling technologies, that have opened up access, to this natural gas.
Beneath the surface, of the mid-Atlantic region, is a rock formation, known as Marcellus Shale.
It is pretty deep, in some locations, as much as 9,000 feet below the ground.
Inside the shale rock, are very tiny pores, mostly microscopic, like the tiny holes, in a piece of bread, only smaller.
Trapped inside those pores, is natural gas.
The natural gas is there, because of the breakdown of organic matter, that was trapped in the rocks, when they formed, long ago.
Until recently, natural gas, in Marcellus Shale, has been very difficult, for people to collect, and use, as a source of energy, mostly because those pores are so small.
Oil and gas have been produced in this region, for over 150 years.
That oil and gas was collected, from rock formations, other than the Marcellus Shale.
Those formations are shallower, or closer to the Earth's surface, and have larger cracks and pores, that hold the oil and gas.
When wells are drilled, in these other formations, they are drilled straight down, or vertically into the rock.
Water and additives, injected at high pressure, or explosives, are used near the bottom of the wells, to help open up, and connect those cracks, to get the gas and oil flowing.
Because the cracks and pores were relatively large, the gas could flow right into the drilled well hole, and up to the surface.
In contrast, the Marcellus Shale holds the gas more tightly, in its tiny pores, and chemical bonds also hold the gas to the small particles, that make up the shale.
To the naked eye, shale looks like this.
You can't see the gas in the pores.
Only with the aid, of scientific instruments, such as an electron microscope, can you see these very tiny spaces, that hold the gas.
When drilling for gas, in Marcellus Shale, horizontally-drilled wells produce much more gas than vertical wells, because they increase the wells' contact with this rock formation, underground.
Hydraulic fracturing is then used, to open up the shale's fractures, and connect the pores, to allow the oil and gas to flow, to the well.
A similar situation occurs, in other nearby shale formations as well, like the Utica Shale.
Utica Shale is a deeper rock formation, found underneath the Marcellus Shale, throughout the same general area of the mid-Atlantic.
The trapped natural gas, in Marcellus Shale, can now be collected, because of recent advancements in technology.
The advancements include the combining of technologies, known as horizontal drilling, and hydraulic fracturing.
In horizontal drilling, the well starts out vertical, but makes a gradual turn underground, until it's running parallel, to the surface.
The turn can take up to a quarter mile, and the well can extend an additional mile, for 5,280 feet, or more, once it's running horizontal, through the shale.
This long, horizontal well, will intersect, with natural cracks, and fractures, in the Marcellus Shale.
This helps to increase the amount of natural gas, that comes in direct contact, with the well.
As the gas well is drilled, about 100,000 gallons of water may be used.
The water keeps the drill bit cool, and clean, while drilling.
It also helps keep the well hole open, and bring the cuttings, from the inside of the hole, up to the surface.
Some of that 100,000 gallons of water is tied up, permanently in cement, and some remains in the drilling mud, as seen here, in this picture.
Drilling mud is recirculated, and recycled, as much as possible, and eventually disposed of, typically via landfill.
Even with a horizontal well, the gas in Marcellus Shale is still tightly bound to the rock.
Another type of technology is used, to release it.
Hydraulic fracturing, often just called fracking, injects water, mixed with sand and chemicals, into the newly drilled well, under high pressure.
This pressure opens up the existing cracks, in fractures, to help the natural gas escape.
It takes roughly four to five million gallons of water, to hydraulically fracture a single Marcellus Shale gas well.
Between 2007, and 2011, more than 4,000 wells were drilled in Pennsylvania, alone.
That adds up, to more than 16 billion gallons of water, used for drilling, and fracking.
That's enough water to fill over 25,000 Olympic-sized swimming pools!
So, where does all this needed water come from?
Let's take a closer look, at the journey water takes, starting from before it's used, in a shale gas well.
There is a lot of surface water, in the mid-Atlantic region.
Surface water includes lakes, rivers, streams, and more.
There's also a lot of groundwater, or water found beneath the surface, in soils, rock formations, or aquifers.
This water is naturally moving, through the water cycle.
Let's follow a drop of water, through the natural water cycle, first.
Let's imagine, a drop of water, that is floating down a stream.
That drop of water will eventually flow into a larger river, or lake.
After a longer journey, the drop of water is likely to enter an even larger body of water, like a bay, gulf, or a sound.
Or, even flow directly into the ocean.
The water drop may spend quite a bit of time, drifting around in the ocean.
It will mingle, with billions upon billions of other drops of water.
One sunny day, it will absorb enough heat energy, to evaporate into a gas, and drift up into the sky.
As a gas, the water moves around more quickly, and freely.
It could drift many miles away, over the Earth.
As the gaseous water vapor moves, it will come into contact, with cooler air.
This causes it to condense, back into a liquid, or even freeze into a solid, when it's cold enough, making it visible in the sky, as part of a cloud.
Liquid and frozen water drops can stay aloft in the sky, when they are small, and lightweight.
As the drops of water gather together, however, they become too heavy, to stay in the air, and they begin to fall back to the Earth.
They may fall at a number of different forms of precipitation, such as rain, snow, sleet, or hail.
When precipitation hits the Earth's surface, it may soak into the ground.
This is called, infiltration.
If a water drop infiltrates the soil, it may be used by plants.
If a plant soaks the water drop, up through its roots, it will soon be released, out of pores, in the leaves, on a fast track, back to the sky, through a process, called transpiration.
Of course, water underground may also spend a long time, slowly trickling through the rocks and soils, until it seeps out of a spring, or collects in an aquifer.
An aquifer is an underground rock, or soil formation, that stores water, like a sponge.
Aquifers are the source of the well water, that many people use, in their homes.
A water drop, falling to the Earth's surface, as precipitation, may also be moving so fast, that it's carried away, over the ground, before it has time to infiltrate.
This is called, runoff.
Runoff water moves downhill, until it collects in a low-lying area.
This could be a stream, a lake, or a river.
And so, our water drop has returned to where it had originally started, back in a stream, completing the water cycle.
Because water moves in a cycle, many people call it a renewable resource.
However, no new water is actually being made on Earth.
All the water we have on Earth now, is all of the water we will ever have.
The majority of water used, for well drilling and fracking, in the mid-Atlantic region, is collected from surface waters, like streams, lakes, and rivers.
For each gas well drilled, in the Marcellus Shale, about 90% of the water is freshwater.
While most of that comes from surface water sources, some freshwater is purchased from public water companies.
The other 10% of water used, for fracking, is water that is being reused for a previously developed Marcellus Shale well.
Surface water is usually available near the drilling sites.
This makes it very affordable.
That is why most of the water used, for fracking, is surface water.
Water acquisition, when water is collected from surface water, or public water companies, is where our water drop leaves its usual path, around the water cycle.
The water drop now begins a new journey, to become part of the shale gas drilling process.
It is important for the water to be mostly free of contaminants, in order to be used for fracking.
Sometimes, the water nearby is too polluted to be used, without being treated first.
This can increase the cost.
We will talk more about water treatment, later in this presentation.
Each state has regulations, that control how much water can be taken, from various surface water sources.
The regulations are different in each state, and within portions of individual states.
Shown here, is a natural body of water, that is suffering from drought.
The original edge of the water is indicated by the yellow tubing.
Notice how far the water level can drop, just from changes in precipitation rates.
Regulations, on the amount of water, that can be withdrawn for drilling, and other uses, help to make certain, that smaller streams and lakes don't run completely dry, during droughts.
A stream, with too little water in it, means less water, for other uses, by humans and wildlife.
It also means, that water can become polluted more easily, since it would only take a small amount of pollution, to alter the stream.
Once the water is collected, or purchased, it's transported to the well site, where it will be used.
It may be transported, by temporary pipelines, or trucked to the drilling site, and stored in tanks, or impoundments.
Our water drop is on the move!
When it is time to frack the well...
The water is mixed with sand and chemicals.
Each drilling company has its own private recipe, for mixing water, sand, and chemicals, for fracking.
Picture here, is a sandhog, a truck that carries sand, parked on a Marcellus Shale gas well pad.
The water mixture is then injected into the well, under high pressure.
Our water drop is now deep underground.
In Pennsylvania, about 90% of the water used, during fracking, remains underground.
It is absorbed, by the dry shale.
Our water drop may end its journey here, remaining deep in the shale formation, and it's unknown, whether this water will reenter the water cycle.
Do you remember that earlier, we said that 90% of the water used for fracking, is newly collected freshwater, and 10% is reused water?
About 10% of the water, injected for fracking, will come back up, to the surface of the well.
This water is called flowback water.
Flowback water can be used again, in the future, to frack another Marcellus well.
Flowback water typically makes up about 10% of the water being injected into a well, for hydraulic factoring.
Once the well starts producing gas, any additional water, that returns to the surface, is called produced water.
A dehydrator unit is used to remove produced water, from the gas, before the gas goes into the pipeline.
The volume of produced water is typically much smaller than the volume of flowback water.
But, comes out over the well's life.
Our water drop may have returned to the surface, either as flowback water, or produced water.
Flowback water and produced water are considered wastewater.
They must go through a wastewater treatment process, if they're going to be returned to the environment, or reused, for fracking.
The water is treated, to remove any contaminants, that were not in the water, before it was used, in fracking the well.
The water will also collect rock particles, salts, metals, and even natural radioactivity.
These contaminants come from contact with the shale, while underground.
Notice, the difference between between the colors of the beaker labeled, as Before Treatment, which contains flowback water, and the one labeled as After Treatment.
We will discuss the third beaker, Brine for Disposal, in just a few moments.
Federal and state rules protect water bodies, and public drinking water.
These rules limit the amount of pollutants, released into the environment, including something called total dissolved solids, or TDS.
TDS can include anything, that is dissolved in water, that you cannot see.
Contaminants, that you can see floating in the water, are called total suspended solids.
In Marcellus gas, drilling wastewater, total dissolved solids, TDS, consists mainly of salts and metals.
The levels of TDS, in fracking wastewater, are usually very high.
Most towns have a municipal wastewater treatment plant.
These plants are generally designed to treat household wastewater.
They cannot properly treat water, that was used in shale gas drilling.
Instead, special treatment plants, for industrial waste are used.
Many of these plants use a process, called distilling, or evaporation, in order to clean the water.
Distilling involves heating the wastewater to a boil.
The water evaporates, and then the vapor's captured as condensation, into a separate, clean container, leaving behind the total dissolved solids.
Diluting, filtering, and chemically precipitating the wastewater, are other common approaches, to treating this recycled water.
More industrial waste treatment plants are being built, or considered, to handle the high volumes of wastewater, from shale gas drilling.
Distilling and other wastewater treatment technologies leave behind a very salty mixture of solid and liquid wastes, called brine.
Brine must be disposed of properly.
Usually, it is injected into underground disposal wells.
Other technologies are being developed, for the future.
Most drilling companies reuse as much of their flowback water as possible.
This saves them money, because they can collect less freshwater, for use in their next well.
A water drop, that returned to the surface's flowback water is most likely going to end up back in another shale gas well.
And again, may end its journey there, trapped in the shale.
Treated water, that is not reused, may be discharged back into surface water bodies, like rivers, lakes, or streams.
If that's the case, our water drop would return to traveling through the natural water cycle.
A small portion of fracking wastewater does not get treated.
About 10% of the water is disposed of, in underground injection control wells.
Water is forced far below the ground, into rocks, that have an impermeable natural layer above them.
Most of these injection sites are in Ohio.
When wastewater is injected underground, that is also an end to our water drop's journey.
It is, again, so deep underground, that it is unlikely to reenter the water cycle.
We're still working, to better understand how much water is permanently trapped underground, due to the fracking process.
We're also still learning about how much water returns to the water cycle.
We also need to better understand how much water is moving great distances, during the shale gas drilling process.
Remember, that freshwater is moved through pipelines, or by trucks, when it is collected.
The water also travels, when flowback water is treated, discharged, or disposed of.
As the water moves, it may travel out of one watershed, and into another.
A watershed is an area of land, that drains to a specific river, stream, or other body of water.
Do you remember, in our water cycle discussion earlier, we talked about water moving downhill, until it collects at a low-lying place, like a river, or a stream?
We can predict which body of water a drop of rain will roll into, because the water will not move uphill.
A watershed's boundaries are formed by the peaks of hills, or a mountain, surrounding the body of water.
We can map the watershed, for very small streams, but also for very large rivers, and bays.
Water used, for shale gas drilling, may be collected, from one watershed, but moved into another watershed, during its journey.
This is important to understand, for those keeping track of water use, and shale gas drilling.
It also affects measurements, and how much water is being returned to the environment, and the water cycle.
Shale gas drilling has grown quickly, in the mid-Atlantic region.
Many technologies are also changing, and adapting quickly.
The speed and changes, make it difficult, to accurately record the use, treatment, and discharge of all of the water involved in this process.
You can expect to see new regulations, and laws developed, as shale gas drilling continues in this region.
These new laws and regulations may also change the journey of a water drop, through the shale gas drilling process.
Frequently Asked Questions