Relationship between fractures, fault zones, stress, and reservoir productivity in the Suban gas field, Sumatra, Indonesia

Hennings, Peter; Allwardt, Patricia F.; Paul, Pijush; Zahm, Chris; Reid, Ray; Alley, Hugh; Kirschner, Roland; Lee, Bob; Hough, Elliott

doi:10.1306/08161109084

Cited by 127 publications

(62 citation statements)

References 18 publications

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“…The Coulomb failure criterion with Byerlee friction coefficients is the standard rule of thumb in predicting whether or not nonoptimally oriented faults can be reactivated in the present-day stress regime [e.g., Sibson, 1985;Jaeger et al, 2007]. Such methods are widely applied in the energy and mining industry and perform remarkably well in practice [e.g., Hennings et al, 2012]. It is tempting to identify the ratio of shear to effective normal stress governing fault operation with a "friction coefficient," as is routinely done within the literature.…”

Section: Discussionmentioning

confidence: 99%

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

2013

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[1] The majority of crustal faults host earthquakes when the ratio of average background shear stress b to effective normal stress eff is b / eff 0.6. In contrast, mature plate-boundary faults like the San Andreas Fault (SAF) operate at b / eff 0.2. Dynamic weakening, the dramatic reduction in frictional resistance at coseismic slip velocities that is commonly observed in laboratory experiments, provides a leading explanation for low stress levels on mature faults. Strongly velocity-weakening friction laws permit rupture propagation on flat faults above a critical stress level pulse / eff 0.25. Provided that dynamic weakening is not restricted to mature faults, the higher stress levels on most faults are puzzling. In this work, we present a self-consistent explanation for the relatively high stress levels on immature faults that is compatible with low coseismic frictional resistance, from dynamic weakening, for all faults. We appeal to differences in structural complexity with the premise that geometric irregularities introduce resistance to slip in addition to frictional resistance. This general idea is quantified for the special case of self-similar fractal roughness of the fault surface. Natural faults have roughness characterized by amplitude-to-wavelength ratios˛between 10 -3 and 10 -2 . Through a second-order boundary perturbation analysis of quasi-static frictionless sliding across a band-limited self-similar interface in an ideally elastic solid, we demonstrate that roughness induces an additional shear resistance to slip, or roughness drag, given by drag = 8 3˛2 G * / min , for G * = G/(1 -) with shear modulus G and Poisson's ratio , slip , and minimum roughness wavelength min . The influence of roughness drag on fault mechanics is verified through an extensive set of dynamic rupture simulations of earthquakes on strongly rate-weakening fractal faults with elastic-plastic off-fault response. The simulations suggest that fault rupture, in the form of self-healing slip pulses, becomes probable above a background stress level b pulse + drag . For the smoothest faults (˛ 10 -3 ), drag is negligible compared to frictional resistance, so that b pulse 0.25 eff . However, on rougher faults (˛ 10 -2 ), roughness drag can exceed frictional resistance. We expect that drag ultimately departs from the predicted scaling when roughness-induced stress perturbations activate pervasive off-fault inelastic deformation, such that background stress saturates at a limit ( b 0.6 eff ) determined by the finite strength of the off-fault material. We speculate that this strength, and not the much smaller dynamically weakened frictional strength, determines the stress levels at which the majority of faults operate.Citation: Fang, Z., and E. M. Dunham (2013), Additional shear resistance from fault roughness and stress levels on geometrically complex faults,

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Section: Discussionmentioning

confidence: 99%

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

2013

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“…The eastern side has a complicated geological history mixing thicker and thinner places, younger and older crust, the magnitude of earthquakes is not higher than M 6.0; however the intensity of earthquakes at eastern side is much more destructive than the western with the same magnitude. Recently Hennings et al [5] discussed the relationship between stress, stress heterogeneity, and the permeability of subsurface fractures and faults. They analyzed a Sumatra region, Indonesia.…”

Section: Resultsmentioning

confidence: 99%

Induced Earthquakes Correlations With Earth’s Crustal Thickness

Hagen¹

2016

geomate

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ABSTRACT:In this paper, we carried out an investigation about the possible causes for enhancement of earthquakes in USA over the last seven years. From our calculations, indications set forth that the increased evolution of the quakes in the country is due to the human actions. For further analysis, we divided the country into three main seismological regions: western, central and, eastern. We roughly classified the areas by their thickness of Earth's crust in a variation 25-45-25 km. The thickest area is in the mid-continent and most of this region are part of the Great Plains. In our study, we are going to investigate the reason for the Mississippi Lime in Oklahoma a very thick area, started an unusual earthquake activity since 2010, most at Oklahoma/ Kansas border. In this region, also, there are many anthropogenic activities concerning with the waste water wells and more than 4000 of them active at the moment in the state. The enhancement of earthquakes cluster is investigated in other locations in the USA. Those studies elsewhere indicated that the anthropogenic reasons vary; one of the most important is the deep waste water disposal used to recycle contaminated water extracted from the gas and oil wells, and other independent sources will be examined. We intend to explain why not all the waste wells are triggering earthquakes and how it would be strongly attached to the unevenness of the Earth's crust.

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“…What are pre-stress conditions on the fault within its seismic cycle, and how do they affect induced events? What role do fault damage zones play in communicating fluid pressures over large distances (Hennings et al, 2012)? What metrics are there for tracking how close a fault might be to failure during fluid injection?…”

Section: Knowledge Gaps Between Earthquake Theory and Observationmentioning

confidence: 99%

Scientific Exploration of Induced SeisMicity and Stress (SEISMS)

et al. 2017

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Abstract. Several major fault-drilling projects have captured the interseismic and postseismic periods of earthquakes. However, near-field observations of faults immediately before and during an earthquake remain elusive due to the unpredictable nature of seismicity. The Scientific Exploration of Induced SeisMicity and Stress (SEISMS) workshop met in March 2017 to discuss the value of a drilling experiment where a fault is instrumented in advance of an earthquake induced through controlled fluid injection. The workshop participants articulated three key issues that could most effectively be addressed by such an experiment: (1) predictive understanding of the propensity for seismicity in reaction to human forcing, (2) identification of earthquake nucleation processes, and (3) constraints on the factors controlling earthquake size. A systematic review of previous injection experiments exposed important observational gaps in all of these areas. The participants discussed the instrumentation and technological needs as well as faults and tectonic areas that are feasible from both a societal and scientific standpoint.

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Relationship between fractures, fault zones, stress, and reservoir productivity in the Suban gas field, Sumatra, Indonesia

Cited by 127 publications

References 18 publications

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

Induced Earthquakes Correlations With Earth’s Crustal Thickness

Scientific Exploration of Induced SeisMicity and Stress (SEISMS)

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