The document discusses environmental concerns and quality assurance/quality control practices regarding shale gas drilling and hydraulic fracturing. It covers topics such as well construction, cementing, casing, mud selection, fracturing, water sourcing and management, and monitoring. It emphasizes the importance of best practices like baseline water testing, closed-loop systems, secondary containment, inspection, and optimization to safely develop shale gas resources while protecting water and the environment.
27. Myths about hydraulic fracturing The methane in homeowners’ wells is nothing more than naturally-occurring methane that has been there for centuries and is unrelated to drilling activities; and The idea that fracking fluids injected at roughly 1,000-2,000 meters below the surface would migrate up into shallow groundwater aquifers makes no geologic sense.
28. Methane source identification The number of protons determines what kind of element it is. For example, any atom with six protons is carbon (C). But an element can have different numbers of neutrons and these are known as different isotopes of the same element. For example, carbon with six neutrons (called C-12) and carbon with seven neutrons (C-13) are two carbon isotopes. The cool thing about isotopes? Their abundance in a given chemical can vary depending on how the chemical is produced. So scientists can use isotopic labels to identify the chemical’s origins. That’s exactly what Osborn et al did to determine the source of methane in the wells. And lo and behold they found: that the methane composition in the most contaminated wells was consistent with thermogenic methane (methane formed at high temperatures deep underground), that the methane in a subset of water samples from Pennsylvania’s Susquehanna County isotopically matched methane from nearby gas wells, but that outside the one-kilometer zone of active drilling, the isotopic fingerprint was significantly different, representing a mixture of both shallow natural biogenic and deeper thermogenic methane.
