Hypocenter Estimation of Induced Earthquakes in Groningen

Self Cite

124

The increase in number and strength of shallow induced seismicity connected to the Groningen gas field since 2003 and the occurrence of a M L 3.6 event in 2012 started the development of a full probabilistic seismic hazard assessment (PSHA) for Groningen, required by the regulator. Densification of the monitoring network resulted in a decrease of the location threshold and magnitude of completeness down to ∼ M L = 0.5. Combined with a detailed local velocity model, epicentre accuracy could be reduced from 0.5-1 km to 0.1-0.3 km and a vertical resolution ∼0.3 km. Time-dependent seismic activity is observed and taken into account into PSHA calculations. Development of the Ground Motion Model for Groningen resulted in a significant reduction of the hazard. Comparison of different implementations of the PSHA, using different source models, based on either a compaction model and production scenarios or on extrapolation of past seismicity, and methods of calculation, shows similar results.

Section: Earthquake Locationmentioning

confidence: 99%

Section: Earthquake Locationmentioning

confidence: 99%

Development of seismicity and probabilistic hazard assessment for the Groningen gas field

Dost

Ruigrok

Spetzler

2017

Self Cite

124

“…(NAM, 2016a). Black lines indicate current reservoir fault model (NAM, 2016a (KNMI, 2017;Spetzler & Dost, 2017 Netherlands Journal of Geosciences -Geologie en Mijnbouw…”

Section: Groningen Fieldmentioning

confidence: 99%

“…Geobodies extracted from the ant tracking attribute show more detailed fault geometry than manually interpreted faults and Spetzler & Dost (2017) and the updated Huizinge ML 3.6 hypocentre (Dost & Kraaijpoel, 2013). Black line indicates seismic section (Fig.…”

Section: Detailed Fault Geometries Based On Seismic Attributesmentioning

confidence: 99%

Improved definition of faults in the Groningen field using seismic attributes

Kortekaas¹,

Jaarsma²

2017

The Groningen field is the largest onshore gas field in Europe. The gas-bearing section comprises aeolian and fluvial Rotliegend sandstones of Permian age and fluvial sandstones of Carboniferous age. Continuous production since 1963 has led to induced seismicity starting in the early 1990s.Faults at reservoir level play a major role in the seismicity in the Groningen field. Fault slip is expected when shear traction is sufficient to overcome frictional resistance on the fault surface. Clear insights into which faults and fault segments are most susceptible to seismicity could be used to optimise production and minimise the seismic risk. To gain these insights, a detailed and realistic fault model is required as input to both statistical analyses on seismicity and deterministic geomechanical modelling of seismogenic behaviour along fault planes. Geometrical seismic attributes and, subsequently, fault planes were extracted from a reprocessed and depth-imaged 3D seismic volume. This resulted in a detailed visualisation of the faults at reservoir level, with extension into the deeper strata below the reservoir in many cases. They represent fault planes with realistic dimensions and shapes. The fault map based on seismic attributes suggests the presence of faults that have not been included in studies on Groningen seismicity before. The improved fault definition correlates with recent earthquake hypocentres. We conclude that a detailed fault model of the Groningen field can be created using 3D seismic attributes and that detailed 3D fault planes can be extracted from these attributes. The results can be used as input to statistical and geomechanical analyses on seismicity.

“…This caused significant public concern. Since that time, the operator, NAM, has invested heavily in extending seismological instrumentation of the field, and it is becoming increasingly clear that the events recorded tend to occur within or close to the reservoir interval (Spetzler & Dost, 2017) and near, or on, the 500 µm σ e gas out, …”

Section: Introductionmentioning

confidence: 99%

New approaches in experimental research on rock and fault behaviour in the Groningen gas field

Spiers

Hangx

Niemeijer

2017

This paper describes a research programme recently initiated at Utrecht University that aims to contribute new, fundamental physical understanding and quantitative descriptions of rock and fault behaviour needed to advance understanding of reservoir compaction and fault behaviour in the context of induced seismicity and subsidence in the Groningen gas field. The NAM-funded programme involves experimental rock and fault mechanics work, microscale observational studies to determine the processes that control reservoir rock deformation and fault slip, modelling and experimental work aimed at establishing upscaling rules between laboratory and field scales, and geomechanical modelling of fault rupture and earthquake generation at the reservoir scale. Here, we focus on describing the programme and its intended contribution to understanding the response of the Groningen field to gas production. The key knowledge gaps that drive the programme are discussed and the approaches employed to address them are highlighted.Some of the first results emerging from the work in progress are also reported briefly and are providing important new insights.