GEOL 110 1st Edition Lecture 7Outline of Last Lecture I. Renewable v. Alternative EnergyII. Renewable Energya. Hydropowerb. Windc. Solard. GeothermalIII. Alternative Energya. Hydrogenb. NuclearOutline of Current Lecture II. Natural Gas ReviewIII. What is shale?IV. HydrofrackingV. Fracking ControversiesVI. Produced WaterCurrent LectureI. Natural Gas ReviewA. Advantages: Minimal processing, Burns cleanly, More energy per unit weight than any other fossil fuel, More energy per unit of CO2 than any other fossil fuel, Extensive infrastructure already in place to handle gas, New technologies might make gas a transportation fuel, Extensive reserve growth in the US spurred by fracking technologies B. Disadvantages: sometimes it explodes, methane can leak from pipelinesC. Natural gas tends to form at lower depths and higher pressures than oil doesD. Natural Gas is important to the future of the US because1. There’s lots of natural gas still in the ground in the US, The heat potential for worldwide natural gas reserves is equal to that of oil reserves, Current estimates are for300 years of natural gas supply for the US, Natural gas can replace coal for electrical power generation, New technologies may make natural gas a transportation fuel, These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Natural gas reserves in the US are near populated areas where the gas can be consumed, Infrastructure for gas is in place.E. It’s the fact that natural gas may be turned into a transportation fuel that makes frackingtechnologies, horizontal drilling and shale gas the kind of game changer that could really make North American energy independence a possibilityII. What is shale?A. Fine-grained sedimentary rock composed of very small (0.002 mm) clay particles. Shales are often rich in organic material, and so fine-grained that tiny details are preserved as fossils.B. Occasionally the organic content is incredibly high – so high that oil has formed, but is trapped in the shale. The oil content of the oil shales are sometimes so high that the rock burns easily and can be lit with a match.C. Conventional gas reserves: occur in porous and permeable reservoir rocks like sandstones, where gas may exist alone or in association with oil.D. Unconventional gas reserves: includes tight gas, which occurs in impermeable sandstone reservoir rocks, and shale gas, where the reservoir rock IS the source rock, one that is non-porous and impermeable shale. Reserve growth in natural gas has come primarily in the form of shale gas, which (like shale oil) is extracted by horizontal drilling andhydraulic fracking technologies.III. Hydraulic Fracking “Hydrofracking”A. Fracking has been around since the 1940s and is a mature method of secondary oil recovery.B. Its use as a primary method of developing tight gas and shale gas formation has caused some environmental concerns: Water pollution, groundwater contamination, and induced earthquakesC. Fracking: the process of pumping of water, sand and chemicals at high pressure into oil and gas wells to fracture the rock and thereby make it possible to more efficiently extract more oil and gas. D. Hydraulic fracturing : the process of extracting natural gas directly from the source and reservoir rockE. Fracking is now often done in wells drilled horizontally into shale formations that containhydrocarbons (oil and gas) but are very fine-grained, due to their high clay content, and soare nonporous and impermeable. Fracking these formations now makes it possible to extract the large quantities of oil and gas that they often contain.F.Best shale gas reserves: in Texas, Marcellus reserves (parts of NY, NJ, PA, VA, OH, KT, MD, TN)IV. Fracking ControversiesA. The water is pumped back out from fracking contains harmful chemicals, but that water is often needed by the local people and it is hard to remove the chemicals from the water. There is also a massive amount of water needed (1-8 million gallons) for the life of each drilling site. B. Water injections: Variety of sources, Proximity to drill site, Three to four million gallons for typical horizontal shale gas well, 0.5 to six million gallons for hydraulic fracturing of the Marcellus Shale (can be up to 8 million gallons though), Used in relatively short time period,Mixed with sand and proprietary solutionsC. Dick Cheney made it legal (by amending the safe drinking water act) to use unknown chemicals to extract oil and natural gas as long as diesel fuel is not used. 1. The government does not heavily regulate the water system to prevent water pollutionD. Environmental problems: minor tremors to large earthquakes, methane leaks into water pipelines, potential explosionsE. The primary environmental risks with fracking operations are water pollution, groundwater contamination and depletion, and induced earthquakesV.Produced WaterA. Byproduct of the stimulation and drilling process. Before natural gas can be recovered, water that is pumped into the shale must be allowed to flow out as “produced water” 1. Can consist of fracturing fluids, heavy metals, brine waters, dissolved minerals ororganic matter from the shale2. Generally this happens well below the water table (what the local populations uses for their homes), so it doesn’t affect the public. B. Wastewater Treatment Plants1. Cannot handle the quantity of water used (up to 8 million gallons of water)2. Unsure of the chemical composition of the proprietary chemicals used in the acid fracturing process (unsure of what to try and purify from the water because so many different typwes of chemicals are used)3. Do not successfully remove salts and other dissolved solidsC. Additional Treatment Methods1. Re-inject produced water into the ground at a shallow depth2. Re-inject produced water into the ground at a depth below the Marcellus Shale3. Allow wastewater to evaporate from open pits or tanks4. Dilute produced water and reuse it in future fracturing operations5. New technology6. CANNOT pump it back into the water