More than One Way to Frack a Well

Our ability to recover natural gas buried in deep geological deposits beneath the earth has increased dramatically due to advances in horizontal drilling which allows a vertically drilled well to turn and run thousands of feet laterally through the earth combined with advances in methods to "hydraulically fracture" or "hydraulically stimulate" the formation to generate cracks or "fractures" through which gases and liquids can flow more rapidly to the well. Hydraulic fracking as it is typically called is the pumping of millions of gallons of chemicals and water into shale at high pressure to increase the recovery of oil and natural gas from shale.

In hydraulic fracking on average 2-5 million gallons of chemicals and water is pumped into the shale formation at 9,000 pounds per square inch and literally cracks the shale or breaks open existing cracks and allows the trapped natural gas to flow. The use of water laced with chemicals to enhance oil and gas production has been very successful in the United States with many improvements in the technique since its inception in the 1950's. Water-based fracturing liquids (once called slickwater) are the most commonly used in the lower shale formations like the Marcellus. Generally, chemical additives are mixed with the water to improve its ability to transport the proppant, the sand or other substance used to prop open the fractures to allow the gas to flow. This is achieved through the addition of gels to increase the viscosity and also to reduce fluid loss from the fracture by temporarily blocking the natural permeability of the rock. Once the pumping is completed, the gel breaks down and the spent liquids can flow back to the surface after which the gas can flow up to the well bore. This works well in the higher pressure formations where the back pressure from the formation can push the liquids out of the formation rather than absorb the liquids into the formation.

While geologists and engineers believe that there is little risk that the fracking “water,” a mix of chemicals and water, will somehow infiltrate groundwater reserves though a fissure created by the fracking. It is believed that the intervening layers of rock would prevent a fissure from extending thousands of feet to the water table, but there are other risks in how we build wells and fracture the shale. There have been documented cases of seepage into drinking water wells through improperly sealed or abandoned drilling wells. There are also places where groundwater is only several hundred feet above the gas reserves as in Wyoming and groundwater is more easily directly impacted by fracking. In the past decade the advances in drilling and fracking technology have been adapted to exploit gas in the Barnett shale in the Fort Worth Basin in Texas and applied to a series of major shale gas deposits that could not have been viable without the advances in drilling and fracking techniques.

A mild winter combined with the newly available gas supplies has resulted in a crash in gas prices. At the current rate of natural gas consumption North America is reported to have a 100-year supply of proven, producible reserves and even with expanded use of natural gas to replace coal in fueling power plants, there is more than a generation of currently accessible reserves. The falling price of natural gas and disappointing life span of hydro fracked wells has renewed interest in other methods of fracturing a formation to increase the gas recovery over the life of the well and reduce the overall costs of fracking including the costs associated with waste water treatment to improve the economics of the project. Other methods of fracturing a formation have been used in formations where the gas reservoir is at a lower pressure and does not have sufficient energy to push the liquids back up the well. Without adequate pressure in the formation the liquids and chemicals used in the hydraulic stimulation process remain in the reservoir and impede the flow of oil and gas and shorten the lifetime of the well.

From the 1970’s until about 10 years ago it was standard to stimulate wells with nitrogen gas or nitrogen foam. Nitrogen gas and foam have a long history as the fracturing fluids of choice in the Antrim, New Albany, and Ohio (Lower Huron) shale where experience had shown a dry fracturing was superior. However, it was the Marcellus shale formations that tipped the balance to hydraulic fracturing. Water is non-compressible, drives net pressure better in shale stimulations than nitrogen foam fluids. Using water improved the chances of opening other planes of weakness or natural fractures with high pump rates and fluid volumes. It was believed that the Marcellus shale gas recovery was not significantly impacted by clays absorbing water and reducing overall gas production in a hydraulic frack; however, this belief may not prove to be true over the life of the wells.

Now, other methods of fracturing shale formations are being examined in response to the public outcry against the potential ground water contamination from hydraulic fracturing, excessive water use and earthquakes associated with some fracking water disposal wells combined with some hydraulic fracture wells experiencing a lower production yield than anticipated and the depressed price of natural gas. In the late 1990’s a series of test wells were drilled by industry and studied by the Department of Energy, DOE. These wells used liquid phase carbon dioxide, CO2, for fracturing and had significantly increased gas well yield over nitrogen fracked wells. In these wells, CO2 was pumped as a liquid then vaporized to a gas and flowed out from the reservoir leaving no liquid or chemical damage to the formation. This process can transport proppant in only limited volumes and requires a specialized blender to mix the liquid CO2 with proppant. These limitations were a problem for the lower shale formations where more proppant was needed.

Sometimes in a hydraulic frack the gels do not completely break down and even when they do, there is always some residue that remains in the well and can block and damage the gas reservoir. Hydraulic fracking gels create some damage, but the fractures were of sufficient length to offset the damage in the Texas wells which popularized the method. Some geological formations; however, do not respond as effectively to hydraulic stimulations. The fracturing liquids can become trapped in the formation because the reservoir is at a lower pressure and does not have sufficient energy to push the liquids back to the well bore. The gas well yields are diminished because the liquids and chemicals used in the fracking remain in the reservoir and impede the flow of oil and gas. These problems were slow to be addressed because of the high price for natural gas last decade, termination of the Gas Research Institute and a sharp decline in DOE gas research and technology program just as shale gas production was taking off.

Now with the low price for natural gas and contracts that require drilling, energy companies are looking for better methods of stimulating gas reserves. Chesapeake Energy Corp. has fractured a natural gas well in Ohio's Utica shale using a reported 471,534 gallons of water mixed with carbon dioxide, sand and chemical additives to create a foam that was pumped down the well under pressure to crack the underground rock. In nearby wells hydro fracked by Chesapeake the average water usage was 5.8 million gallons. Well production results from this CO2 foam and water fracked well will have to be evaluated over a period of at least 24 months and typically 36 months to know if this technique was successful, but it holds promise as a less resource damaging or wasting method to access shale gas.

Ohio Fracking and Earthquakes

A series of eleven small earthquakes ranging in magnitude from 2.1 and 4.0 have taken place beneath Youngstown Ohio since March 2010. Each earthquake is reported to have had their epicenters near the Ohio Works Drive injection well used by D&L Energy Inc. to dispose of waste water from nearby hydro fracking jobs. D&L began injecting the waste water from the fracking jobs, referred to as brine, into its Ohio Works well in December 2010.

The earthquakes early in the spring led the Ohio Department of Natural Resources, ODNR, to have Columbia University Lamont-Doherty Earth Observatory install seismic monitoring equipment in the area to determine whether there was any relationship between fracking or water disposal activity and the earthquakes. A report is expected in the near future, but after the earthquakes, on December 30th and 31st, use of the disposal well has been halted. ODNR has halted deep well disposal of fracking waste water in the D&L Ohio Works Drive injection well and four other injection wells in the Youngstown area pending analysis of the data collected by the Lamont-Doherty scientists.

In hydraulic fracking on average 2.8 million gallons of chemicals and water is pumped into the shale formation at 9,000 pounds per square inch and literally cracks the shale or breaks open existing cracks and allows the trapped natural gas to flow. While geologists and engineers believe that there is little risk that the fracking “water,” a mix chemicals and water, will somehow infiltrate through the shale and the thousands of feet to reach the groundwater reserves though a fissure created by the fracking, there are other routes of contamination and impact. An now concern is focused in Ohio on the disposal of the flowback water that is not absorbed into the rock formations.

The water that is absorbed into the rock formations may change the formations in ways we do not yet understand, it is the disposal of the flowback that is the focus of this investigation. Though the water in the hydro frack is exempted from the clean water act (by a 2005 act of congress), the flowback which contains “proprietary” chemicals and contaminates from the geological formation is not and must be disposed under state regulations. This is not the first study of earthquakes associated with the disposal of fracking water.

Researchers of the University of Texas at Austin were part of a team of researchers who studied a series of small earthquakes that struck near Dallas, Texas in 2008 and 2009, in an area where natural gas companies had used fracking. The epicenter of the quakes turned out to be about half a mile from a deep injection disposal well under the Dallas-Fort Worth International Airport used to dispose of the fracking fluid. The largest earthquake of the series measured 3.3 on the Richter scale, a very small earthquake. In a study that was published in the Bulletin of the Seismological Society of America, the researchers also reviewed records from US Geological Survey seismic-recording stations in Oklahoma and Dallas. It was concluded by the researchers that the fracking did not cause the earthquakes, but there seemed to be a relationship to the deep well injection of the fracking fluid to the earthquakes.

Columbia's Lamont-Doherty Earth Observatory scientists have the advantage of having placed seismic monitoring equipment in the area before the last few quakes which included the strongest of the series at 4.0 on the Richter scale on New Year’s Eve. The location of the earthquake epicenter is expected to be in the area of the Ohio Works Drive injection well an area of no previous seismic activity. It has been speculated that the earthquakes were triggered by the fluid injected into the well that permeated a previously unknown fault.

Our ability to recover natural gas buried a mile or more beneath the earth has increased. Advances in horizontal drilling which allows a vertically drilled well to turn and run thousands of feet laterally through the earth combined with advances in hydraulic fracking, the pumping of millions of gallons of water and laced with thousands of gallons of chemicals into shale at high pressure have increased our ability to recover natural gas from shale ahead of our knowledge of the consequences of the fracking and disposal of the waste water. Wastewaters from the hydraulic fracturing process must be disposed of safely, and deep injecting wells had been the favored method. There are 177 similar injection wells around the state of Ohio that will remain in use. The Youngstown-area well has been the only site with seismic activity, according to the ODNR. Only five Youngstown area wells have been shut down.

Fracking in Ohio

The U.S. Forest Service has withdrawn more than 3,200 acres of forest land from a federal oil and gas lease sale scheduled for Wednesday, December 7, 2011. The acreage in Athens, Gallia, and Perry counties was to be included in a broader sale of leases for 20,949 acres of federal land in Ohio, Mississippi and Louisiana. This land was to be auctioned for Hydraulic Fracturing. The Buckeye Forest Council, an environmental coalition, opposed the sale stating that the environmental statement was outdated because it did not mention hydraulic fracturing. In addition, they feel that Ohio does not have the regulatory framework to deal safely with fracking. The auction plan is on hold pending the review of the environmental impact statement which could take up to six months and lead to required revisions in the 2006 environmental impact statement which could delay the auction further. The 3,200 acres currently have nearly 1,300 shallow gas wells.

Our ability to recover natural gas buried a mile or more beneath the earth has increased. Advances in horizontal drilling which allows a vertically drilled well to turn and run thousands of feet laterally through the earth combined with advances in hydraulic fracking, the pumping of millions of gallons of water and laced with thousands of gallons of chemicals into shale at high pressure have increased our ability to recover natural gas from shale. Hydraulic fracking is a technology that was unknown 60 years ago. Until recently there was no economically feasible way to extract this gas.

Thought industry executives say fracking has been widely used for decades without problems, hydraulic fracturing has changed, the type of hydraulic fracturing the industry executives are talking about is coal bed formation fracturing. The volume of water needed for hydraulic fracturing varies by site and type of formation. Fifty thousand to 350,000 gallons of water may be required to fracture one well in a coal bed formation while two to five million gallons of water may be necessary to fracture one horizontal well in a shale formation. Water used for fracturing fluids is acquired from surface water or groundwater in the local area. Wastewaters from the hydraulic fracturing process must be disposed of and several ways have been used. Several of the techniques tried have been to dispose of the water underground using injection wells, discharged to surface waters after treatment in a waste water treatment plant designed to remove only solids and biological contaminants, or applied to land surfaces where it can seep into the water table.

The millions of gallons of water used for fracking shale contain up to 15,000 gallons of chemical additives. The chemicals serve to increases the viscosity of the water to a gel-like consistency so that it can carry the propping agent (typically sand) into the fractures to hold them open so that the gas can flow. Determining the proper methods for the safe disposal of the large quantities of this fracking fluid that may also contain contaminants from the geological formation including brines, heavy metals, radionuclides and organic contaminants is essential. The deep well injection of the waste in Texas is believed by scientists to have triggered the earthquakes near the Dallas airport. The impact of so much waste water on our water resources must be measured and monitored. Finally, care must be taken to avoid degradation of watersheds and streams from the industry itself as large quantities of heavy equipment and supplies are moved on rural roads and placed on concrete pads.

There are many possible routes to contamination from fracking. Errors in natural gas well construction or spills during injection can occur and lead to drinking water contamination. Drinking water wells contaminated by methane and potassium chloride have been reported. In Pennsylvania, flammable levels of methane in drinking water wells and potassium chloride levels high enough to salinize a drinking water aquifer have been reported in the vicinity of some gas wells. Fracking fluids can spill before they are injected and fluids recovered from fracturing can contaminate surface waters. The EPA estimates that 15-80% of the volume of fracking fluids injected will be recovered. The amount of fluid recovered depends on the site geology. Additionally, drilling into the subsurface through the water table can create pathways for fracking fluids or natural gas to find its way into water supplies and wells, if grouting isn’t properly done and the gas well properly constructed. The horizontal sections of the wells are not cased in cement and, introduce a potential point where fracking fluids can reach the outside of the grouting during flowback.

Hydraulic fracturing should continue slowly. A limited number of wells should be installed with careful monitoring of local and regional groundwater supplies as well as verification of proper well construction and wastewater recycling. Limiting fracking to a small area of the federal and state forest lands would allow the development of experience, knowledge and data, and could ensure careful restoration of the area. Instead of leaving unwary homeowners to the “land men” and their leases written entirely to favor and protect the drilling and gas companies, allow the state governments to develop standard language for the gas leases and the federal government to collect real time data in a secluded area away from residential impact.

Currently, the US Environmental Protection Agency (EPA) is studying the impact of hydraulic fracturing on water resources, but they are only focusing on the potential to directly pollute the drinking aquifer, not looking at potential changes in the groundwater hydrology. The geological impact of Hydraulic Fracturing should be examined by the U.S. Geological Survey. No one has ever looked at what the long term implications are for the hydraulic balance when fracking occurs. The removal of millions of gallons of water, the fracturing of the geological formations, and the injection of contaminants even at low concentrations into the subsurface could cause significant changes in groundwater flow and quality.

The current regulatory framework concerning hydraulic fracturing has a number of gaps that need to be addressed before unlimited fracking takes place. There were several recommendations made in the report of the Shale Gas Subcommittee of the Secretary of Energy Advisory Board. The report had a rational approach to regulation recommending disclosure, testing, evaluation and modification of regulation and practices based on the information and data obtained. It assumes information and data will be gathered and analyzed. That is not yet being done. The data needs to be collected on a state level and provided to the US Geological Survey and US EPA to consolidate on a national level.

In the past decade the advances in drilling and fracking technology have been adapted to exploit gas in the Barnett shale in the Fort Worth Basin in Texas and applied to a series of major shale gas deposits that could not have been viable without the advances in drilling and fracking. The Fayetteville shale, the Haynesville shale, the Marcellus shale reserves all in the United States and the Horn River shale reserves in Canada are now accessible. At the current rate of natural gas consumption North America is reported to have a 100-year supply of proven, producible reserves and even with expanded use of natural gas, there is more than a generation of currently accessible reserves. We need to treat both the earth and its resources with respect.

In truth we have no viable option to hydrocarbon fuel. When the oil and gas is gone it will be a poorer future without airplanes, freighters and trucks. Sailing ships will not transport raw materials and finished goods around the earth. Solar and wind power will produce unreliable power supplies and mankind will adapt (not happily) or discover new sources of fuel. Before that future world arrives, the shale gas and oil sands and whatever else is discovered will be exploited. There is no urgency, but you cannot permanently stop that trend. These deposits will become more valuable over time as the world becomes more desperate for energy. Now is the time to carefully develop and study the methods to exploit these resources without destroying or further damaging the earth.