Science of hydraulic fracturing contains materials questions
- PDF / 199,470 Bytes
- 2 Pages / 585 x 783 pts Page_size
- 101 Downloads / 206 Views
•
Energy Sector Analysis
Materials scientists’ expertise in fracture dynamics could help bring more scientific insights to the current debate surrounding the fracking process
Science of hydraulic fracturing contains materials questions By Melissae Fellet Feature Editors Michael Marder and Tad Patzek
H
orizontal drilling and hydraulic fracturing is becoming common across the United States as a method of producing oil and natural gas trapped in deep shale formations. Proponents argue that the process, commonly called “fracking,” will spur economic growth by providing low-cost energy from a domestic source of natural gas. Opponents worry that leaks of gas and chemicals used during hydraulic fracturing could contaminate groundwater and impact public health. A 2012 report on hydraulic fracturing prepared by the Pacific Institute, a non-profit research group, found little peer-reviewed literature on the process or its environmental impacts; thus, opinion dominates dialogue on the issue. The expertise of materials research, if turned to questions around hydraulic fracturing, could help bring more science-based information to the debate. Conventional wells tap into pockets of oil and natural gas formed when the hydrocarbons collect in underground reservoirs. Well operators produce the hydrocarbons by drilling vertically into these reservoirs. Unconventional wells access hydrocarbons where they originally formed inside shale formations. Hydraulic fracturing involves injecting a high-pressure fluid into the shale to generate a network of cracks through which gas and oil can flow. This process, when combined with horizontal drilling to increase access to the hydrocarbons, became economically viable for horizontal wells in shales only in the early 2000s. The technological advances in unconventional drilling are fueling natural gas production in the United States. In 2011, shale gas accounted for 34% of US natural gas production. By 2040, shale gas is expected to be 50% of the country’s total gas production. Here’s how the process of horizontal drilling and hydraulic fracturing works today. Well operators drill a hole vertically into the ground. Drilling continues at an angle as the bore nears the shale, often more than 2000 meters deep. Then the bore turns so the well runs horizontally through the shale layer. Throughout drilling, the crew lines the bore with steel casings. After the well is fully drilled and lined, the crew blasts holes through the casing in the horizontal portion of the bore. Fluid is pumped into the well at high pressure, blasting out of the holes in each “fracturing stage” and cracking the rock sur-
Michael Marder and Tad Patzek, University of Texas at Austin, USA Melissae Fellet, [email protected]
484
MRS BULLETIN
•
VOLUME 39 • JUNE 2014
•
www.mrs.org/bulletin • Energy Quarterly
rounding the bore. There can be 10 to 20 fracturing stages along each horizontal section of a well, which extends for 1500–3000 meters. The “frac” fluid mostly consists of water, a suspended granular solid-like
Data Loading...
