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In the last 12 years Mexico has drilled some 924 wells using a fracking technique which has polluted water sources, according to data from CartoCrítica, a non-profit civil organization that aims to protect human rights and the environment.
Mexican authorities have used water from some 21 aquifers to carry out fracking in those wells. The water used to drill these wells is between 8.3Mm3 and 26.7Mm3, CartoCrítica director Manuel Llano told BNamericas.
The shale gas wells were drilled in the northern border states of Nuevo León (182 wells), Tamaulipas (100), and Coahuila (47), as well as in the Gulf coast states of Veracruz (349), Puebla (233) and Tabasco (13).
The drilling and operation of these wells has not been managed by Pemex, as it has hired the services of oil companies like Halliburton, Schlumberger and Baker Hughes, companies that may now participate in tenders for Round One contracts.
Mexico's energy ministry Sener said that until 2010, Mexico had drilled 1,323 fracking wells in the Chicontepec basin alone, but it has not provided details on other regions where fracking is taking place, according to CartoCrítica.
It is estimated that each shale gas well requires between 9,000m3 and 29,000m3 of water, Llano said.
Water used for fracking is mixed with around 750 different chemicals which can produce cancer and mutations in humans, affect the endocrine system, cause allergies and damage the nervous system, Llanos claimed. As yet there is no effective treatment process for this water, he added.
Areas in Mexico where fracking takes place. CREDIT: CartoCrítica
The wastewater from fracking is pumped into disposal wells which, due to the high volumes of water they contain, are claimed to cause earthquakes. However, these wastewater wells not recorded in the public registry of water rights (Repda) by the national authority Conagua, Llanos said.
Conagua "is not complying with the regulations. There is a irregularity," the CartoCrítica representative said.
"We don't know the volumes of toxic water and where they are deposited. The location of the disposal wells must be registered."
Other issue that concerns says Manuel Llano, is filtration of the polluted water that has been used for fracking.
"It is estimated that five out of every 20 wells, or 25% of the total wells have leaks of toxic water during exploration, while there are more leaks during production of shale gas," Llanos said.
Aquifers that are used to extract water for fracking. (CREDIT: CartoCrítica)
CartoCrítica estimates that some 4.5 million people in Mexico are affected by extraction of hydrocarbons through fracking.