Fractures in the Dutch Rotliegend—An overview

Ligtenberg, Herald; Okkerman, Jos; Keijzer, Martin de

doi:10.2110/pec.11.98.0229

Cited by 7 publications

(17 citation statements)

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“…Outcrop studies and fracture analysis showed that fault cores in Rotliegend sandstone consist of cataclastic material, fault gouge and breccia (Ligtenberg et al, 2011; see also Fig. 6D).…”

Section: Fault Friction and Weakening Through Slip-dependent Loss Of mentioning

confidence: 99%

Fault reactivation mechanisms and dynamic rupture modelling of depletion-induced seismic events in a Rotliegend gas reservoir

Buijze

Boogert

Wassing

et al. 2017

Netherlands Journal of Geosciences

105

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Understanding the mechanisms and key parameters controlling depletion-induced seismicity is key for seismic hazard analyses and the design of mitigation measures. In this paper a methodology is presented to model in 2D the static stress development on faults offsetting depleting reservoir compartments, reactivation of the fault, nucleation of seismic instability, and the subsequent fully dynamic rupture including seismic fault rupture and near-field wave propagation. Slip-dependent reduction of the fault's strength (cohesion and friction) was used to model the development of the instability and seismic rupture. The inclusion of the dynamic calculation allows for a closer comparison to field observables such as borehole seismic data compared to traditional static geomechanical models. We applied this model procedure to a fault and stratigraphy typical for the Groningen field, and compared the results for an offset fault to a fault without offset. A non-zero offset on the fault strongly influenced the stress distribution along the fault due to stress concentrations in the near-fault area close to the top of the hanging wall and the base of the footwall. The heterogeneous stress distribution not only controlled where nucleation occurred within the reservoir interval, but also influenced the subsequent propagation of seismic rupture with low stresses inhibiting the propagation of slip. In a reservoir without offset the stress distribution was relatively uniform throughout the reservoir depth interval. Reactivation occurred at a much larger pressure decrease, but the subsequent seismic event was much larger due to the more uniform state of stress within the reservoir. In both cases the models predicted a unidirectional downward-propagating rupture, with the largest wave amplitudes being radiated downwards into the hanging wall. This study showed how a realistic seismic event could be successfully modelled, including the depletion-induced stressing, nucleation, dynamic propagation, and wave propagation. The influence of fault offset on the depletion-induced stress is significant; the heterogeneous stress development along offset faults not only strongly controls the timing and location of a seismic slip, but also influences the subsequent rupture size of the dynamic event.

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“…Outcrop studies and fracture analysis showed that fault cores in Rotliegend sandstone consist of cataclastic material, fault gouge and breccia (Ligtenberg et al, 2011; see also Fig. 6D).…”

Section: Fault Friction and Weakening Through Slip-dependent Loss Of mentioning

confidence: 99%

Fault reactivation mechanisms and dynamic rupture modelling of depletion-induced seismic events in a Rotliegend gas reservoir

Buijze

Boogert

Wassing

et al. 2017

Netherlands Journal of Geosciences

105

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“…An understanding of the fault and fracture systems present in the Upper Rotliegend rocks, their relationships to fault rock and surrounding host rock properties, and consequently sealing potential, requires an understanding of the regional tectonic evolution of the area of interest. We present a high-level overview here: for more detail, the reader is referred to Ziegler (1990), Leveille et al (1997), Corona (2005), , de Jager & Geluk (2007) and Ligtenberg et al (2011), and references therein.…”

Section: Structural Setting and Burial Historymentioning

confidence: 99%

“…Geiss 2008). These fault systems in Rotliegend deposits have gone through several phases of reactivation (Ligtenberg et al 2011). Regional subsidence Fig.…”

Section: Structural Setting and Burial Historymentioning

confidence: 99%

Fault seal behaviour in Permian Rotliegend reservoir sequences: case studies from the Dutch Southern North Sea

Ojik¹,

Silvius

Kremer

et al. 2019

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Permian Rotliegend reservoir rocks are generally characterized by high net/gross (N/G) ratios, and faults in such sand-dominated lithologies are typically not considered likely to seal. Nevertheless, many examples of membrane sealing are present in Rotliegend gas fields in the Southern Permian Basin. This manuscript reviews examples of membrane sealing in the Dutch Rotliegend; it presents an extensive dataset of petrophysical properties of Rotliegend fault rocks and analyses two case studies using commonly used workflows. Fault (membrane) seal studies have been carried out on two Rotliegend fields to test the level of confidence and uncertainty of prediction of 'across fault pressure differences' (AFPD) based on existing SGR-based algorithms. From the field studies it is concluded that observable small AFPDs are present and that these are likely pre-production AFPDs due to exploration-time scale trapping and retention of hydrocarbons. Two shale gouge ratio (SGR)-based empirical algorithms have been used here to estimate AFPDs in lower N/G reservoir intervals with the aim of predicting membrane seal behaviour, and these results are compared to field data. It is concluded the selected SGR-based tools predict AFPD for Upper Rotliegend lower N/G reservoir rocks with reasonable results. Nonetheless, the core sample datasets show a much wider range of permeability and capillary entry pressure than predicted by the selected SGR transforms. This highlights the potential to modify existing workflows for application to faults in high N/G lithologies. Data sharing and collaboration between industry and academics is encouraged, so that in the long run workflows can be developed specifically for faults in high N/G lithologies.

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“…Knipe et al, 1998;Ligtenberg et al, 2011). On a geological timescale, large regions can be identified in the Groningen field that display different initial free water levels (NAM, 2016a) suggesting that faults or fault zones acted as barriers to cross-fault communication in the past and may still do so.…”

Section: Fig 2 Regional Setting and Structural Elements Of The Gronmentioning

confidence: 99%

“…Schroot & de Haan, 2003). Expressions of the Alpine inversion event are the local presence of overthrusts and the occurrence of pop-ups along major NW-SE fault trends (Ligtenberg et al, 2011).…”

Section: Regional Tectonic History Of the Groningen Areamentioning

confidence: 99%

Improved definition of faults in the Groningen field using seismic attributes

Kortekaas¹,

Jaarsma²

2017

Netherlands Journal of Geosciences

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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.

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Fractures in the Dutch Rotliegend—An overview

Cited by 7 publications

References 0 publications

Fault reactivation mechanisms and dynamic rupture modelling of depletion-induced seismic events in a Rotliegend gas reservoir

Fault reactivation mechanisms and dynamic rupture modelling of depletion-induced seismic events in a Rotliegend gas reservoir

Fault seal behaviour in Permian Rotliegend reservoir sequences: case studies from the Dutch Southern North Sea

Improved definition of faults in the Groningen field using seismic attributes

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