Risks of contamination of aquifers due to shale gas in Ukraine

Risks of contamination of aquifers due to shale gas - published in Ukrainian

Translated from Ukrainian

This document was translated from Ukrainian -some typos and spelling issues.

Contamination of groundwater by hydrocarbons and chemicals used for drilling and performhydraulic fracturing , is perhaps the greatest environmental risk in the extraction of shale gas .Cause groundwater pollution can be natural vertical fractures in the rock strata, changing hydrological regime due to pumping large quantities of water, the integrity of the winding and obsadky wells, fracturing fluid spills or cuttings to the surface and so on.

The main types of potential groundwater contamination due to shale gas - a penetration of gaseous hydrocarbons (methane, ethane, propane) in aquifers, groundwater pollution to hydraulic fracturing chemicals to the surface as a result of spills or technological errors during hydraulic fracturing, the penetration of contaminants (salts , heavy metals) from the deep layers of the aquifers.

Contamination of groundwater with methane and other hydrocarbons

Representatives of the oil and gas industry have repeatedly stated that there is no proven link between cases of pollution of groundwater and conducting hydraulic fracturing operations.However, many American familiesdeclare the contamination of their water wells methane as a result of shale gas.

The most publicized cases of water contamination have become methane residents Dimok (Pennsylvania) and Pavillion (Wyoming).

January 1, 2009 in the town Dimok exploded drinking water wells located in the yard of one of the apartments. The locals have linked the explosion of shale gas. 15 families who thought their water contaminated with methane,filed a lawsuit against the company Cabot Oil and GasThat led shale gas near. The trial lasted several years, during which the company paid fines and time supplying drinking water Dimoka residents. In December 2010, was signed the next version of the settlement in which Cabot Oil and Gas has not accepted his guilt, but agreed to pay compensation to residents of the double value of their property and to install water filters from methane. Some families refused to install filters, considering them unreliable, and continued fighting. In December 2011, Cabot Oil and Gas has stopped water supply to the affected families.From January to June 2012 Agency of the U.S. Environmental Protection Agency examined the quality of drinking water in the town and DimokconcludedThat despite not exceeded for certain contaminants in individual wells, cleaning equipment can bring water quality to an acceptable level and the situation with water supply requires no further intervention agency or provision of alternative water supplies. However, in August 2013There are new calls to resume the investigation caused by publishing internal presentation of one of the employees of the agency, which contains information about the elevated levels of methane in water Dimok town that was not properly reflected in the conclusions of the Agency for Environmental Protection.

Residents of the town of Pavillion appealed to the Agency for the U.S. Environmental Protectionwith complaints about the quality of drinking water in the spring of 2008. Specialists Agency selected water samples from 39 wells in March 2009 and a further 23 wells in January 2010. In addition, water samples were taken in areas of shale gas and two specially drilled for water quality monitoring deep wells. In December 2011, the agency published an initial report on drinking water quality study to collect stakeholder comments. Term collecting comments repeatedly postponed because more research has splysty water and at the end of September 2013. The next step will be an independent peer review report. Bythe initial reportfrom private wells for water supply was confirmed by the presence of thermogenic methane origin, and its concentration generally increased with decreasing distance to the gas producing wells. In addition, the study confirmed groundwater contamination with organic substances in wells near the barns for storing cuttings and return waters.

There are several scientific studies that demonstrate the link elevated levels of methane in groundwater and extraction of shale gas.

In 2011 was published study Scientists from the University of Duke (Duke University). The researchers said they were able to document the contamination of drinking water by methane as a result of shale gas. Water samples were selected from 68 private wells for water depths ranging from 36 to 190 meters in the states of Pennsylvania and New York. The water was analyzed for dissolved salts, hydrogen and oxygen isotopes ( 18 O and 2 H) and carbon isotopes, radium and barium. 60 out of 68 wells and tested for dissolved methane and more complex hydrocarbons and isotope ratios of carbon and hydrogen in methane molecules. Methane was detected in water samples from 50 wells (85% of all wells surveyed). Methane concentration was on average 17 times higher in wells that are located within less than 1 km from the shale gas than in boreholes around which there was no gas production (within 1 km). Average methane concentration in water were respectively 19.2 mg / L and 1.1 mg / l. The maximum concentration of methane in selected samples was 64 mg / l. Content analysis of isotopes of carbon and hydrogen in a molecule of methane and analyzes the content of higher hydrocarbons (ethane, propane, butane) confirmed that methane in water wells are located near places of extraction of natural gas, has a thermogenic origin from deep horizons, while methane from wells around which did not occur in shale gas, had biological or mixed origin. However, the study found no evidence for contamination of groundwater occurrence of deep water with a high salt content or liquids for hydraulic fracturing. Among the possible mechanisms for getting methane in water horizons researchers call the integrity obsadky wells and natural cracks in underground rock, which may be exacerbated as a result of hydraulic fracturing operations.

In 2013 was published supplemented by scientific researchhigh concentration of methane in drinking water in shale gas Marsellus. This time the tests were done drinking water from 81 wells at a depth of 60-90 meters north-east of Pennsylvania and will provide preliminary data analyzes 60 wells. Methane content was recorded in 82% of all water wells (115 wells with 141). The content of methane in water from wells that are located within a radius of 1 kilometer from the wells where shale gas is extracted, was 6 times higher than in water from wells that are located further from gas production sites. The content of ethane in these groups differed in the wells 23 times. Analysis of heavy isotopes of carbon and hydrogen in the molecules of methane, ethane and propane indicates the predominant thermogenic origin of gaseous hydrocarbons in water from wells located near the site of production of natural gas. PROBABLE CAUSE penetration of thermogenic methane from deep levels in aquifers researchers call damaged steel obsadky wells and the integrity of the winding cement wells.

In both studies, draws attention to the need for further study of contamination of aquifers in the extraction of shale gas. It is important to have a basic tracking of content and composition of gaseous hydrocarbons in water, and disclosure of the chemical composition of shale gas produced and isotope ratios of its key components.

Contamination of groundwater elements for hydraulic fluid

Study on cases of groundwater contamination from chemicals fracturing fluid is more limited and is usually associated with emergency situations in the extraction of hydrocarbons.

In 2011, the Council for the Conservation of Energy Resources Alberta (Alberta Energy Resource Conservation Board) investigated the contamination of drinking waterdue to hydraulic fracturing wells Caltex, which was made in violation of rules. Crew Energy Company due to an error in September 2011 had perforated wells and hydraulic fracturing operation above the safety zone aquifer at a depth of 136 meters. It was used 20 tons of sand and 130 cubic meters of condensed propane (used as a material for hydraulic fracturing). To monitor groundwater contamination was drilled two wells to collect water depth 81 (depth of water intake for water) and 137 (depth of fracturing) meters 50 meters from the well where fracturing was conducted.Propane and izopropanolamin, used for hydraulic fracturing were found in a deep hole, but traces of their penetration into the upper levels were recorded. As a result, Commission concluded that the risk of contamination of drinking water as a result of the incident is insignificant. Water quality monitoring program in the incident will continue.

Most cases of potential groundwater contamination due to spills of substances for hydraulic fracturing wastewaters or drill cuttings to the surface areas of extraction of natural gas.However, such emergency situationshave a local character and can lead to contamination of soil or located near surface waters and less likely - to contamination of underground aquifers.

For example, in April 2011 explosion at the well of Chesapeake Energy Corp. In the state of Pennsylvania. The explosion of used hydraulic fluid flowed from the well to the surface for more than 12 hours until emergency crews who flew up from Texas, did not stop the leak. After the explosion in selected wells of local residents water sampleswere foundelevated concentrations of barium, strontium, iron and chloride. In water samples from five monitoring wells was detected content of chlorides, metals, and ethanol. Their content, however, was named one that is generally consistent with local water quality and is quite small. It was concluded that due to the saturation of soil moisture used in hydraulic fracturing fluid has not penetrated into the lower layers of soil and aquifers soiled. The company Chesapeake Energy Corp. wasliable to pay over 250 thousand dollars of fines and compensation due to the incident.

Contamination of groundwater due to infiltration of pollutants from deep horizons

If confirmed and documented groundwater contamination due to migration of contaminants (salts, heavy metals, etc.) in deep layers, where the fracturing, the aquifer is currently for sale.This can be explained by a significant migration potential of such duration and complexity of installation due to a high content of heavy metals in water and conduct hydraulic fracturing.

The specialists of the University of Texas in July 2013 published researchdrinking water wells near shale gas field Barnett. Chemical analysis was carried out for 100 samples of water from private wells. The analysis revealed that the content of heavy metals (arsenic, selenium, strontium) in some wells that were within 3 miles of active gas wells exceeded the maximum permissible dose for drinking water. In 29% of wells was also found the contents of methanol and ethanol. ResearchersnoteThat heavy metals are still encountered in groundwater in the region, but historical data indicate that their content is so high is unusual and unnatural. Content of heavy metals in water from wells within 3 miles of which there is no natural gas was within normal limits. However, there were wells located very close to the place of extraction of natural gas, where the content of heavy metals was also within normal limits. Researchers emphasize the need for more detailed studies and noted that although there is no reason to establish a clear link between high levels of heavy metals and methanol extraction of shale gas, but the geographical distribution of problematic water samples and historical data indicate the possibility of such a relationship.

Ways to minimize the risk of groundwater pollution due to shale gas

In  study by AEA Technology plc, Commissioned by the Directorate General Environment of the European Commission, presented the following recommendations to minimize the negative impact of shale gas on groundwater quality:

• baseline monitoring and ongoing systematic monitoring of the chemical composition of water in aquifers near mining sites;
• limiting the use of hydraulic fracturing method in areas with a high risk of groundwater contamination (small depth-bearing rocks, the presence of natural fractures, etc.);
• implementation of appropriate standards and quality control procedures obsadky and cementing wells;
• Requiring building barns for ground storage of drill cuttings and return water;
• control over the process of hydraulic fracturing to prevent exit faults beyond the target horizon to prevent excess pressure and the amount of fluid to hydraulic fracturing, which is pumped into the well, avoiding spills of hazardous substances and waste and so on.

The initial step that will enable linking groundwater pollution from shale gas extraction is detailed basic tracking of drinking water before carrying out any work. Company BF Environmental Consultants Inc.Which is in charge of monitoring the quality of water resources,recommended perform basic analysis of water for at least pH, conductivity, turbidity, bacteria content, chlorides, nitrates, bromides, barium, total dissolved solids, surfactants, iron, manganese, methane, ethane and propane. Additionally it is possible to analyze the water content of magnesium, strontium, zinc nitrate, MTBE, persistent organic pollutants, radioactivity, etc.. The exact optimal set of elements for analysis, according to the head of Mr. Oram also depends on local geological conditions and previous land use.

Thus, shale gas is a significant risk factor for contamination of groundwater, and therefore requires proper regulation and monitoring of the environment and compliance with technical requirements. Documented cases of groundwater contamination confirm the possibility of penetration of methane and other gaseous hydrocarbons into water horizons, which can be characterized not only shale gas but also for conventional gas production. Contamination of groundwater chemicals used in fracturing may occur due to spills of hazardous substances on the surface of the earth or of a violation of hydraulic fracturing technology. Cases of groundwater pollution to hydraulic fracturing substances due to their vertical migration of thick shale rocks in aquifers currently for sale.

We were cited in the article - have not reviewed the article  just posted it in English.

Thanks

Brian Oram