scholarly journals Stress-based forecasting of induced seismicity with instantaneous earthquake failure functions: Applications to the Groningen Gas Reservoir.

2021 ◽  
Author(s):  
Jonathan Smith ◽  
Elias Heimisson ◽  
Stephen Bourne ◽  
Jean-Philippe Avouac
Keyword(s):  
Steady State ◽  
Induced Seismicity ◽  
Dimensional Space ◽  
Gas Production ◽  
Surface Subsidence ◽  
Coulomb Stress ◽  
Detailed Knowledge ◽  
Initial Strength ◽  
Reservoir Compaction ◽  
Stress Changes

The Groningen gas field is a natural laboratory to test stress-based forecasting models of induced seismicity due to the detailed knowledge of the reservoir geometry and production history, as well as the availability of surface subsidence measurements and high quality seismicity data. A specific feature of that case example is the exponential rise of seismicity that was detected nearly 30 years after the onset of production. In this study, the subsurface is represented as a homogeneous isotropic linear poroelastic half-space subject to stress changes in three-dimensional space due to reservoir compaction and pore pressure variations. The reservoir is represented with cuboidal strain volumes. Stress changes within and outside the reservoir are calculated using a simple convolution with semi-analytical Green functions. The uniaxial compressibility of the reservoir is spatially variable and constrained with surface subsidence data. Coulomb stress changes are maximum near the top and bottom of the reservoir where the reservoir is offset by faults. To assess earthquake probability, we use the standard Mohr-Coulomb failure criterion assuming instantaneous nucleation and a non-critical initial stress. The distribution of initial strength excess, the difference between the initial Coulomb stress and the critical Coulomb stress at failure, is treated as a stochastic variable and estimated from the observations. We calculate stress changes since the onset of gas production. The lag and exponential onset of seismicity are well reproduced assuming either a a generalized Pareto distribution of initial strength excess, which can represent the tail of any distribution, or a Gaussian distribution, to describe both the tail and body of the distribution. This representation allows to test if the induced seismicity at Groningen has transitioned to the steady-state where seismicity rate is proportional to the stressing rate. Our results indicate that the system has not yet reached such a steady-state regime. The forecast is robust to uncertainties about the ability of the model to represent accurately the physical processes. It does require in particular a priori knowledge of the faults that can be activated. The method presented here is in principle applicable to induced seismicity in any setting provided deformation and seismicity data are available to calibrate the model.

scholarly journals Predicting ground subsidence due to long term oil/gas production in a Niger Delta basin, Nigeria: implications for CO2 EOR and geosequestration

2021 ◽  
Author(s):  
Fidelis Ankwo Abija ◽  
Tamunoene. K. S. Abam
Keyword(s):  
Niger Delta ◽  
Gas Production ◽  
Surface Subsidence ◽  
Rock Properties ◽  
Ground Subsidence ◽  
Economic Losses ◽  
Reservoir Pressure ◽  
Formation Pressure ◽  
Stress Changes ◽  
Pressure Depletion

Abstract Reservoir pressure depletion with production leading to porosity loss, compaction and surface subsidence are the effect of effective stress changes and the imposition of the overburden stress which was partly supported by the fluids on the rock grain skeleton. Ground subsidence is associated with environmental hazards, failure of operational facilities and damages to infrastructures amounting to huge economic losses. In this studies, subsidence has been assessed using the Geertsma nucleus of strain based on predicted reservoir pressure. Depletion was estimated as percentage pore pressure dissipation and dynamically derived geomechanical and petrophysical rock properties determined. Reservoir porosity vary from 15% – 32%, shale volume from 11.2% − 88%, bulk compressibility range from 2.52–2.53 x 10− 6 /mPa, and uniaxial compaction coefficient 1.15–1.8 x 10− 6/mPa. The vertical compaction in a typical reservoir interval with a thickness of 31.0m varies from 0.002mm to 0.05mm at 10% formation pressure depletion, − 0.005mm to 0.27mm at 50% formation pressure drawdown and 0.007 to 0.53mm at 99% production and reservoir pressure dissipation. surface subsidence would range from 0.045mm to 0.35mm at 10% pressure depletion, 0.058mm to 1.8mm at 50% pressure depletion and 0.045mm to -3.47mm at full reservoir pressure drawdown. At a distance of 92.45km from the Niger Delta coastline, subsidence in the oilfield can still spread to the coastline, the deformation causing damages to the environment, operational facilities and infrastructures that amount to huge economic losses to the operators and government. We recommend the use of CO2 in EOR to maximize production, mitigate subsidence through ground rebound and keep carbon securely sequestered.

scholarly journals Subsidence, tremors and society

2001 ◽  
Vol 80 (1) ◽  
pp. 121-136 ◽  
Author(s):  
H.J. Gussinklo ◽  
H.W. Haak ◽  
R.C.H. Quadvlieg ◽  
P.M.F.M. Schutjens ◽  
L. Vogelaar
Keyword(s):  
Monitoring Program ◽  
Gas Production ◽  
Surface Subsidence ◽  
Large Area ◽  
Reservoir Compaction ◽  
Surface Water Management ◽  
Multidisciplinary Study ◽  
Observation Network ◽  
The Sixties ◽  
Set Up

AbstractThe province of Groningen is flat and level, lying at an elevation close to sea level. The area is intensely cultivated and water table levels are a matter of concern. When the size of the Groningen gasfield was recognized in the sixties, it was realized, that substantial subsidence might occur at the surface affecting a large area.Intensive studies were performed over time to predict future subsidence. These studies are supported by theoretical and experimental research in Shell since the 1950’s concerning reservoir compaction and related surface subsidence. To monitor reservoir compaction and surface subsidence on a regular basis, an extensive monitoring program was set up by NAM. The program comprises leveling surveys, GPS measurements, measurements of shallow formation compaction and in-situ reservoir compaction.In Groningen weak earthquakes have occurred since 1991 at irregular intervals. A multidisciplinary study from 1991–1993 on the relationship between gas production and earthquakes in the northern part of the Netherlands, combined with further studies concluded, that under certain circumstances these earthquakes may result from gas production. Monitoring is carried out through a seismic observation network with borehole sensors and locally installed accelerometers.Because of the expected impact of subsidence induced by gas production on surface water management, an Agreement was concluded between the Province of Groningen and NAM.In line with the 1983 Agreement the ‘Commissie Bodemdaling’ was founded, in which both NAM and the Province of Groningen are represented. On the basis of NAM predictions and actual measurements this Committee determines, what measures are to be taken to prevent, minimize or to correct for effects of gas production induced surface subsidence.

scholarly journals Prior oil and gas production can limit the occurrence of injection-induced seismicity: A case study in the Delaware Basin of western Texas and southeastern New Mexico, USA

Geology ◽  
2021 ◽  
Author(s):  
Noam Z. Dvory ◽  
Mark D. Zoback
Keyword(s):  
New Mexico ◽  
Pore Pressure ◽  
Induced Seismicity ◽  
Large Scale ◽  
Oil And Gas ◽  
Water Injection ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Delaware Basin ◽  
Stress Changes

We demonstrate that pore pressure and stress changes resulting from several decades of oil and gas production significantly affect the likelihood of injection-related induced seismicity. We illustrate this process in the Delaware Basin (western Texas and southeastern New Mexico, USA), in which hydraulic fracturing and waste-water injection have been inducing numerous earthquakes in the southernmost part of the basin where there has been no prior oil and gas production from the formations in which the earthquakes are now occurring. In the seismically quiescent part of the basin, we show that pore-pressure and poroelastic-stress changes associated with prior oil and gas production make induced seismicity less likely. The findings of this study have important implications for the feasibility of large-scale carbon storage in depleted oil and gas reservoirs.

scholarly journals Field-wide reservoir compressibility estimation through inversion of subsidence data above the Groningen gas field

2017 ◽  
Vol 96 (5) ◽  
pp. s117-s129 ◽  
Author(s):  
Rob M.H.E. van Eijs ◽  
Onno van der Wal
Keyword(s):  
Induced Seismicity ◽  
Surface Deformation ◽  
Gas Production ◽  
Potential Threat ◽  
Gas Field ◽  
Reservoir Compaction ◽  
The Difference ◽  
Seismological Model ◽  
Groningen Gas Field ◽  
Deformation Measurements

AbstractNot long after discovery of the Groningen field, gas-production-induced compaction and consequent land subsidence was recognised to be a potential threat to groundwater management in the province of Groningen, in addition to the fact that parts of the province lie below sea level. More recently, NAM's seismological model also pointed to a correlation between reservoir compaction and the observed induced seismicity above the field. In addition to the already existing requirement for accurate subsidence predictions, this demanded a more accurate description of the expected spatial and temporal development of compaction.Since the start of production in 1963, multiple levelling campaigns have gathered a unique set of deformation measurements used to calibrate geomechanical models. In this paper we present a methodology to model compaction and subsidence, combining results from rock mechanics experiments and surface deformation measurements. Besides the optical spirit-levelling data, InSAR data are also used for inversion to compaction and calibration of compaction models. Residual analysis, i.e. analysis of the difference between measurement and model output, provides confidence in the model results used for subsidence forecasting and as input to seismological models.

scholarly journals ANALYSING POST-SEISMIC DEFORMATION OF IZMIT EARTHQUAKE WITH INSAR, GNSS AND COULOMB STRESS MODELLING

2016 ◽  
Vol XLI-B1 ◽  
pp. 417-421 ◽  
Author(s):  
R. Alac Barut ◽  
J. Trinder ◽  
C. Rizos
Keyword(s):  
Measurement Techniques ◽  
Satellite System ◽  
Northern Region ◽  
Strike Slip ◽  
Coulomb Stress ◽  
North West ◽  
Coulomb Stress Changes ◽  
Izmit Earthquake ◽  
The North ◽  
Stress Changes

On August 17<sup>th</sup> 1999, a M<sub>w</sub> 7.4 earthquake struck the city of Izmit in the north-west of Turkey. This event was one of the most devastating earthquakes of the twentieth century. The epicentre of the Izmit earthquake was on the North Anatolian Fault (NAF) which is one of the most active right-lateral strike-slip faults on earth. However, this earthquake offers an opportunity to study how strain is accommodated in an inter-segment region of a large strike slip fault. In order to determine the Izmit earthquake post-seismic effects, the authors modelled Coulomb stress changes of the aftershocks, as well as using the deformation measurement techniques of Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS). The authors have shown that InSAR and GNSS observations over a time period of three months after the earthquake combined with Coulomb Stress Change Modelling can explain the fault zone expansion, as well as the deformation of the northern region of the NAF. It was also found that there is a strong agreement between the InSAR and GNSS results for the post-seismic phases of investigation, with differences less than 2mm, and the standard deviation of the differences is less than 1mm.

scholarly journals Drill core from seismically active sandstone gas reservoir yields clues to internal deformation mechanisms

Geology ◽  
2020 ◽  
Author(s):  
Berend A. Verberne ◽  
Suzanne J.T. Hangx ◽  
Ronald P.J. Pijnenburg ◽  
Maartje F. Hamers ◽  
Martyn R. Drury ◽  
...  
Keyword(s):  
Microstructural Analysis ◽  
Gas Production ◽  
Drill Core ◽  
Gas Reservoir ◽  
Gas Field ◽  
Reservoir Compaction ◽  
Key Factor ◽  
Forecasting System ◽  
Internal Deformation ◽  
Dauphiné Twinning

Europe’s largest gas field, the Groningen field (the Netherlands), is widely known for induced subsidence and seismicity caused by gas pressure depletion and associated compaction of the sandstone reservoir. Whether compaction is elastic or partly inelastic, as implied by recent experiments, is a key factor in forecasting system behavior and seismic hazard. We sought evidence for inelastic deformation through comparative microstructural analysis of unique drill core recovered from the seismogenic center of the field in 2015, 50 yr after gas production started, versus core recovered before production (1965). Quartz grain fracturing, crack healing, and stress-induced Dauphiné twinning are equally developed in the 2015 and 1965 cores, with the only measurable effect of gas production being enhanced microcracking of sparse K-feldspar grains in the 2015 core. Interpreting these grains as strain markers, we suggest that reservoir compaction involves elastic strain plus inelastic compression of weak clay films within grain contacts.

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