Environmental Impact of Hydraulic Fracturing Treatment Performed on the ŁEBIEŃ LE-2H WELL

abarrelfullabarrelfull wrote on 05 Mar 2012 09:04
Tags: gas poland shale upstream

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Soil, air, water – the studies show that all these elements of the environment are safe if exploration of shale gas is conducted in accordance with legal regulations. Today the Polish Geological Institute presents for the first time a complex report on environmental impact of hydraulic fracturing.

May exploation of shale gas create risk for natural environment? This question casts deep shadow on Poland dreams to become the second Norway. Fearful news on effects of hydraulic fracturing keep coming from various places in the world, especially the United States. And this is still the key method for releasing gas entrapped in tiny pores of dark, otherwise impervious Silurian shales which occur at 3-4 km depths in a belt stretching from the central Pomerania to Lublin region.

In order to verify these fearful news, our scientists decided to carry out detailed studies of environment and ground water in area of the first exploratory well in Poland, in which Lane Energy company performed full-scale hydraulic fracturing in the middle of the last year. The studies were conducted on the initiative of the Ministry of the Environment from June 13 till October 13, 2011.

The team of specialists studied environmental conditions and ground water before, during and after the hydraulic fracturing. The studies were coordinated by the Polish Geological Institute and the team comprised geologists and hydrogeologists from the PGI as well as specialists from the Institute of Geophysics of the Polish Academy of Sciences, Voivodeship Inspectorate for Environmental Protection in Gdańsk, Biology Division of the Faculty of Environmental Engineering of the Warsaw University of Technology and Oil and Gas Institute in Cracow. Over 30 specialists took part in the field works, and about 30 - in laboratory studies.

The well named as Łubień LE-2H is 4,075 m deep, with horizontal section 1,000 m long. It is located near Łebień in the Pomerania voivodeship. This is typical agricultural area It is drained by the Kisewska Struga Creek. The main usable ground water horizon occurs at the depth 10 to 20 m below terrain surface but the local population also uses water from shallower horizons.

The hydraulic fracturing was performed by Schumberger on horizontal section of the well from August 19 to 28, 2011. After making holes in steel casing of well bore in 13 intervals of the horizontal section, about 17,322 m3 of water stored in a special reservoir in the well site area was injected into the horizontal section. Before the injection, about 1,271 tonnes of quartz sands and 462 m3 of chemical were added to the water. The role of quartz sand addition was to prevent closing of fissures made by blows of water-based fluid injected into a well under high pressure. In turn, chemicals are added to increase penetrating force of the fluid, prevent growth of bacterial flora and protect well casing from corrosion.

The studies were comprehensive, covering air, soil gas, surface water and usable ground water, soil, noise level and ground vibrations. A special attention was paid to the presence of the major component of natural gas, that is methane, and radioactive radon. The presence of methane would indicate leakiness of cement plugs of the well casing or migration ofthat gas from shale rock layers subjected to hydraulic fracturing. Radon is fairly common in rocks and ground water and, as suggested by some authors, may also escape from gas-bearing shale rock series.

The studies carried out on such scale for the first time in Poland did not show any changes in the natural environment which could be linked with the hydraulic fracturing. Neither methane nor radon were found. Seismic stations of the Institute of Geophysics (20 in number) did not record any shakes in the time of fracturing. Also analyses of water from the Kisewska Struga Creek and 20 water wells did not show any changes from chemical composition as found in detailed studies performed before the hydraulic fracturing. Only noise level turned to be arduous from time to time but only in the direct proximity of aggregates

The studies also covered management of waste and flowback fluids. As expected, a part of injected technological fluid (2,781 m3) came back to the surface. In result of contact with strongly saline water and shales in the zone of hydraulic fracturing the fluids became enriched with chlorides and barium salts. The analyses showed increase toxicity of these fluids in relation to some groups of organisms (crustaceans and plants). The major part of these flowback fluids were subjected to treatment in a special station in the well site area and stored for reuse in hydraulic fracturing to be performed on other wells. The rest was treated as industrial waste fluid and sent to be subjected to specialized methods of utilization. It should be noted that the technological liquids were subjected to continuous supervision.

All the operations carried out at the well site area were conducted in the way minimizing risk of negative impact on ground water. This includes recycling of the flowback fluids, storage of waste in leak-proof containers and protection of land surface with concrete plates and liners made of plastic firm).

It should be added that the use of large quantities of water in hydraulic fracturing operations did not result in decrease of ground water resources in the Łebień well area. This was due to the fact that water was being gathered in leak-proof reservoir for several months, in quantities consistent with the water rights permit.

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