July 2022

What's New in Exploration: Rocks can save or kill the planet

In the category of not throwing rocks, while SEG and AAPG waived formally merging, the two societies are, for the first time, in their respective histories co-sponsoring their annual conventions/conferences during the same week, at the same facility, in Houston this fall.
William (Bill) Head / Contributing Editor

In the category of not throwing rocks, while SEG and AAPG waived formally merging, the two societies are, for the first time, in their respective histories co-sponsoring their annual conventions/conferences during the same week, at the same facility, in Houston this fall. “Upcoming SEG/AAPG International Meetings: Positioning multiple disciplines together to focus on geoscience applications and technologies, this collaborative event was created to better serve the needs of geoscientists in a rapidly changing energy landscape. The result: the largest gathering of earth scientists and energy professionals in the world, 28 August-1 September 2022, George R. Brown Convention Center, Houston, Texas USA.” https://seg.org/Events/Upcoming-SEG-Annual-Meetings. Finally! I have whined about the separation of same-member conventions for years as an excess of cost and ego. No doubt, diminished membership finally forced this logical conclusion. 

Good rocks. SEAM (SEG Advanced Modeling Corporation) continues to offer state-of-the-art solutions to today’s rock/reservoir problems. What is a rock (really), how to evaluate it, observe fluids in it, estimate hydrodynamics of fluid movement flowing in or out, and resulting interdependence of pore volume/permeability/hydraulic conductivity are necessary segments of information to our industry. 

A back-office effort including me and many, many others, is preparing a next generation rock-fluid project that has been underway now for more than two years. The SEAM CO2 Sequestration Project is looking for a sponsor to contribute technically and financially. The project is intended to be presented to DOE. 

Fluid induced seismicity: comparison of rate and state and critical pressure theory. Induced seismicity as generated by the injection of fluids in a homogeneous, permeable medium with faults, with variable proximity to rupture conditions simulated, using the rate- and state-dependent frictional fault theory (RST) of Dieterich (J Geophys. Res 99(B2):2601–2618, 1994) and the critical pressure theory (CPT) developed by Shapiro (Fluid-induced seismicity, Cambridge University Press, Cambridge, 2015). 

In CPT, the induced local seismicity density is proportional to the pressure rate, limited by the Kaiser Effect, and apparently un-related to the tectonic background seismicity. There is no time delay between a change in pressure rate and seismicity density. As a more complex theory, RST includes a time delay between a pressure change and induced seismicity, and it is proportional to the natural tectonic background seismicity. 

Comparing both modeling approaches at a fixed location, this delay can be significant, dependent on a “free” parameter that represents the lower threshold for pressure, below which seismicity is not triggered. This parameter can be tuned, so that the results of CPT and RST become similar. Approximations of the RST allow a new interpretation of the parameter “tectonic potential” that controls the level of induced seismicity in CPT. 

“Fluid‑induced seismicity: Comparison of rate‑ and state‑ and critical pressure theory,” Friedemann Wenzel, Geotherm Energy (2017) 5:5, DOI 10.1186/s40517 017 0063 2. 

Bad rocks. Stretching of the continents caused extreme global warming. A new study led by the University of Southampton has found that stretching of the continents is likely to have “caused one of the most abrupt and extreme global warming events in the history of our planet,” 56 million years ago. During this episode, the Earth warmed by 5o to 8oC, culminating in the “Palaeocene-Eocene Thermal Maximum” (PETM) that lasted about 170,000 years and led to the extinction of many deep-sea organisms, fundamentally reshaping the course of evolution of life on Earth. 

According to the experts, the extensive stretching of the continental plates in the Northern Hemisphere critically reduced the pressures in the Earth’s deep interior, driving a short-lived but intense melting in the mantle. The resulting volcanic activity coincided with—and most probably caused—the release of a massive amount of carbon dioxide in the atmosphere that exacerbated global warming, says Thomas Gernon, an associate professor of Earth Sciences at the University of Southampton. “It’s generally agreed that a sudden and massive release of the greenhouse gas carbon from the Earth’s interior must have driven this event, yet the scale and pace of warming is very hard to explain by conventional volcanic processes.” 

See more on this from Andrei Ionescu, Earth.com, https://www.earth.com/news/stretching-of-the-continents-caused-extreme-global-warming/ 

No rocks. The recent U.S. Supreme Court decision to limit the Environmental Protection Agency (EPA) from inventing law is more than welcome to the fossil fuel industry. In 2015, the Environmental Protection Agency (EPA) promulgated the Clean Power Plan rule, which addressed carbon dioxide emissions from existing coal- and natural-gas-fired power plants…For authority, the Agency cited Section 111 of the Clean Air Act, which, although known as the New Source Performance Standards program, also authorizes regulation of certain pollutants from existing sources under Section 111(d). 42 U. S. C. §7411(d). 

Prior to the Clean Power Plan, EPA had used Section 111(d) only a handful of times since its enactment in 1970…There is little question that the petitioner states are injured, since the rule requires them to more stringently regulate power plant emissions within their borders….Congress did not grant EPA, in Section 111(d) of the Clean Air Act, the authority to devise emissions caps, based on the generation shifting approach the Agency took in the Clean Power Plan…https://www.supremecourt.gov/opinions/21pdf/20-1530_n758.pdf.  

About the Authors
William (Bill) Head
Contributing Editor
William (Bill) Head is a technologist with over 40 years of experience in U.S. and international exploration.
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