Markus Häring - Profile on Academia.edu (original) (raw)

Papers by Markus Häring

Evaluation of flow paths during stimulation in an EGS reservoir using microseismic information

Geothermics

Introduction of in-situ stress information from borehole logging to source characterization of microseismic events

The 13th SEGJ International Symposium, Tokyo, Japan, 12-14 November 2018

GEOPHYSICS

The forecasting and risk assessment of induced seismicity associated with fluid injection have co... more The forecasting and risk assessment of induced seismicity associated with fluid injection have considerable importance for subsurface energy development. We have developed a seismic evaluation method called the possible seismic moment (PoSeMo) model to assess the potential seismic moment that could be released in the future based on current seismic activity. The PoSeMo model assumes the existence of a representative parameter that can describe the seismic characteristics of a given field. This parameter is defined as the seismic moment density, which quantifies the seismic moment able to be released per rock volume. The rock volume presumed to be in critical condition because of stimulation is defined as the stimulated rock volume. The current stimulation condition for the PoSeMo model can be estimated from the product of these two parameters. The difference between the output of the PoSeMo model and the observed cumulative seismic moment corresponds to the cumulative seismic moment that could be released in the future. This value can be transformed into the possible maximum magnitude that has clear physical meaning and that can be used as feedback on the stimulation operation for seismic hazard assessment. We have applied this model to a microseismic data set from the Basel engineered geothermal system project. We have successfully estimated reasonable values for seismic moment density and stimulated rock volume. The PoSeMo model performed well, and it provided reasonable estimates of seismic moment. The maximum magnitude estimated by the PoSeMo model was almost identical to the largest event that had occurred previously. Thus, it was concluded that the PoSeMo model satisfactorily demonstrated its feasibility as a real-time seismic evaluation method, based on physical parameters derived from microseismic information.

Multi-source multi-receiver microseismic reflection imaging: case study Basel

SEG Technical Program Expanded Abstracts 2012

$Research paper thumbnail of Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip$

Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

Geophysical Research Letters

Rupture directivity of fluid-induced microseismic events: Observations from an enhanced geothermal system

Journal of Geophysical Research: Solid Earth

Microseismic reflection imaging and its application to the Basel geothermal reservoir

GEOPHYSICS, 2015

We have developed a new approach for reflection seismic imaging using microseismic waveform data.... more We have developed a new approach for reflection seismic imaging using microseismic waveform data. We took the specific character of microseismic downhole data into account and were able to image regions in the direct vicinity or inside of a seismically active zone. We used a directional migration method that reduced imaging artifacts caused by the low aperture of the data, but required estimation of the wavefield polarization. We also used hodogram analysis to identify parts of data that provided reliable polarization estimates. Only these parts were then used for imaging, whereas the rest of the data are excluded. The approach was successfully applied to microseismic waveforms recorded during and after the stimulation of the enhanced geothermal system in Basel, Switzerland. This data set included more than 2000 events recorded at five sparsely distributed borehole sensors. The reflection images revealed a distinct network of reflectors in the vicinity of the open hole section withi...

$Research paper thumbnail of Characteristics of the large events from the seismically activated fractures at Basel geothermal reservoir$

Proceedings of the 10th SEGJ International Symposium, 2011

The authors analyzed seismic events which include large events with moment magnitude larger than ... more The authors analyzed seismic events which include large events with moment magnitude larger than 2.0 observed during and after the hydraulic stimulation at Basel, Switzerland in 2006. The characteristics of the large events, including time of occurrence, hypocenter location, waveform similarity/difference to the neighboring events, fault plane solutions (FPSs), and seismic source parameters, have been investigated by the authors. We found that the characteristics of the large events, which occurred in deeper and shallower parts of the seismic cloud are different from each other. In this study, we identified orientation of fracture planes on which seismic activity was observed. Critical pore pressure for shear slip, which is considered as one of the triggers of the shear slip on existing fracture plane has been also evaluated for the large events. Many large events had fault plane solution with trend of N-S azimuth and sub-vertical dip, even the stress state of the fracture plane is not the most preferential to slip. Meanwhile, the rests of the large events including the largest one, occurred on the fracture plane with WNW-ESE azimuth trend strikes, which can be interpreted as the most preferential plane to slip in case of coefficient friction is 0.6. Such unbalanced seismic activity and release of seismic energy on fractures with different azimuths are clearly observed for this data.

Proceedings of the 11th SEGJ International Symposium, Yokohama, Japan, 18-21 November 2013, 2013

Induced seismic events with moment magnitude larger than 2.0 occurred during and after a hydrauli... more Induced seismic events with moment magnitude larger than 2.0 occurred during and after a hydraulic stimulation for creation of reservoir of Engineered Geothermal System (EGS) at Basel, Switzerland in 2006. The large events considerably damaged the constructions and resulted in shutdown of EGS project in Basel after risk analyses for further large events. The authors have analyzed the large events and investigated fundamental characteristics of the large events, including time series of occurrence, epicenter location, waveform similarity to the other events, Fault Plane Solutions (FPSs), and source parameters. In this study, we investigated relation between the occurrence of the large seismic events and some possible trigger mechanisms for shear slip of the large seismic events. One of the possible trigger mechanisms is an increase in pore pressure. We estimated the critical pore pressure from the Coulomb failure criterion using the information of the stress state at Basel and the orientation of the fault planes. We observed that the large events occurred just after the final stage of the stimulation at relatively low critical pore pressure. We also estimated diffusion pressure based on diffusion model and the results showed diffusion pressure disturbed even after two months of the stimulation. The other possible trigger mechanism is the static stress redistribution caused by the preceding events. The static stress changes were calculated from orientation of the fault planes and seismic source parameters as input. The result showed that the stress state on the fault plane became stable for most of large events and that the magnitude of the stress change was negligibly smaller than change in pore pressure.

SEG Technical Program Expanded Abstracts 2008, 2008

Microseismic multiplets, which are groups of events showing highly similar waveform despite diffe... more Microseismic multiplets, which are groups of events showing highly similar waveform despite different origin time and magnitude, can be effectively used to determine relative location of the hypocenters with high accuracy. The authors clustered multiplets from microseismic events collected during a hydraulic stimulation in the Deep Heat Mining Project at Basel, Switzerland in 2006. The similarity of waveform was quantitatively evaluated in the frequency domain using the magnitude square coherence function, and this made it possible to cluster the events with different criteria which correlate to different physical phenomena associated with shear slip on fractures. We then interpreted the behavior of each multiplet cluster from the orientation and size of the multiplet seismic structure, fault plane solution, source radius, and hydraulic record. Multiplets which correlate to (a) identical shear slip on a macroscopic single fracture or thin fracture network, (b) repeating slip within a microscopic fracture, and (c) extension of rupture zone on a microscopic fracture, are identified and their response to the stimulation was also interpreted.

SEG Technical Program Expanded Abstracts 2007, 2007

In order to develop an enhanced geothermal reservoir as part of the Deep Heat Mining project at B... more In order to develop an enhanced geothermal reservoir as part of the Deep Heat Mining project at Basel (Switzerland) a hydraulic stimulation program was conducted in deep geothermal well Basel 1 during December 2006. This EGS project is financed by Geopower Basel AG. The stimulation was operated and monitored by Geothermal Explorers Ltd for microseismic activity; more than 13,000 microseismic events were observed during the stimulation and afterwards. Hypocenters of approximately 2,900 events were located onsite. During subsequent analysis, we analyzed microseismic multiplet events that exhibit similar waveforms to those among the located events. 70% of the located events comprise multiplets which may be assigned to over 100 distinct multiplet clusters. We estimated relative hypocenters for 1,635 of the multiplet events using a double differential hypocenter location technique. The relocated hypocenter distribution clearly delineates the reservoir structure to an accuracy of typically less than 10 m. Each multiplet cluster defines a planar or streak structure which has vertical inclination and strikes predominantly along a NW-SE direction; this is generally consistent with local tectonic stress analyses. Hypocenter distribution is uniform within the stimulated volume, suggesting that the reservoir structure lacks any dominant fluid flow path. The temporal and spatial pattern of multiplet response corresponds clearly to the time line and injection volumes of the pumping operation.

The authors analyzed microseismic events with large magnitude collected during and after a hydrau... more The authors analyzed microseismic events with large magnitude collected during and after a hydraulic stimulation of engineered geothermal reservoir at Basel, Switzerland in 2006. Fundamental characteristics of the microseismic events with large magnitude were investigated by hypocentral distribution, source radius, similarity of waveforms to neighboring events, and fault plane solution. Results from these analyses have revealed that most of the large events from the deep part of the stimulated zone originated in ruptures involving multiple asperities. It has also been estimated that the large events in the shallow part of the seismic cloud occurred in fractures that were sub-parallel to the stimulated zone, suggesting that they were the result of different rupture processes to that of the mid-depth and deep large events. We investigated volumetric strain induced by preceding microseismic events to a large event and pore pressure, which are known as possible triggers of shear slip, to interpret physics behind the large events at Basel. Some amount of strain was accumulated around the hypocenters of the large events just before the occurrences, although no clear evidence that strain is the trigger of the large events was obtained. Spatio-temporal distribution of the critical pore pressure for shear slip was estimated using tectonic stress and fault plane solution (FPS). This analysis revealed that critical pore pressure does not directly correlate to the magnitude of microseismic events.

The authors have been developing a new variation of passive reflection technique, where microseis... more The authors have been developing a new variation of passive reflection technique, where microseismic multiplets are used as a source (multiplet reflection imaging using microseismicity: multiplet RIM). Closely similar waveform and precisely determined hypocenter of the multiplet can be effectively used to image structures inside/around the seismically activated EGS reservoirs. In the multiplet RIM, artifacts and blurred reflection image due to limited number of sources and detectors is suppressed by identification of relative/absolute time of arrivals of reflected phase from the multiplets and new concept of inversion. The multiplet RIM has been applied to a data set collected at Soultz, France. The coherence index, which is a measure of arrival of reflected phase in the multiplet RIM, suggested that coherent reflected phase among the multiplets were successfully identified. The reflection image showed that there are possible reflectors at the bottom of shallow reservoir and surrounding zone. The index of reflectivity along a borehole at the site was consistent with results from FMI and PTS logging.

Zusammenfassung Dieser Beitrag fasst die gewonnenen Erkenntnisse aus dem Deep-Heat-Mining-Projekt... more Zusammenfassung Dieser Beitrag fasst die gewonnenen Erkenntnisse aus dem Deep-Heat-Mining-Projekt in Basel zusammen. Neben dem vollständigen Bohrprofil werden petrologische, strukturelle und hydrogeologische Erkenntnisse über das kristalline Grundgebirge präsentiert, welches in der Tiefbohrung Basel 1 (5000 m) angebohrt wurde. Zudem werden die angetroffenen Spannungsverhältnisse charakterisiert und mit Herdflächenlösungen einiger induzierter seismischer Ereignisse in Zusammenhang gebracht. Daraus wird ein Reservoirmodell abgeleitet, welches die Entwicklung des Reservoirs beschreibt.

Rupture Propagation Imaging at Microseismic Scale

London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013

ABSTRACT We further develop the Back Projection technique for tracing the rupture propagation of ... more ABSTRACT We further develop the Back Projection technique for tracing the rupture propagation of microseismic events. We lay out the basic idea of Back Projection imaging and show the results for three synthetic datasets obtained using finite-difference modeling. The synthetic rupture models in use where generated according to microseismic events that occurred at the Basel EGS. They help us to understand the influences of the station geometry and the station weighting process which need to be applied in Back Projection imaging. The focus of the work lies in the analysis of real events and the extraction of their respective properties. We show the corresponding results for the four largest real events of local magnitudes M=3.1-3.4 from the Basel EGS site and discuss the validity and interpretation of the outcome. We find that the obtained rupture dimensions are consistent with the independent magnitude derived estimates. The rupture directions which are obtained fit reasonably well to the shape of the microseismic cloud and to one of the respective fault planes obtained from source mechanism analysis. This supports the validity of our approach. In addition we are hereby capable of solving the fault plane ambiguity.

Investigation on the characteristics of seismic events observed during stimulation of geothermal reservoirs at Basel, Switzerland

Hydraulic stimulation is commonly used to develop engineered geothermal systems (EGS) and enhance... more Hydraulic stimulation is commonly used to develop engineered geothermal systems (EGS) and enhancement of oil recovery (EOR). Occurrence of seismic events with larger magnitude has been highlighted as one of the practical and critical problems. Some seismic events with moment magnitude (Mw) larger than 2.0 occurred during and after hydraulic stimulation in Basel, Switzerland, in 2006, and these large events led to the geothermal project discontinued. We defined the large event as seismic events with Mw>2.0, and have investigated fundamental characteristics of them as summarized in Table 1. It has been revealed that the characteristics of the large events are dependent on hypocentral location and origin time. We also found most of the large events occurred from 2 types of fracture planes: 6 of 9large events had FPSs with N-S azimuth. Other 3 large events including the largest events had FPSs ESE-WNW azimuth, which can be interpreted as "most slip-able" under stress state ...

Fault plane solutions of earthquakes from deep geothermal reservoirs

We have collected seismic data from EGS and hydrothermal geothermal reservoirs at Basel, Switzerl... more We have collected seismic data from EGS and hydrothermal geothermal reservoirs at Basel, Switzerland, Cooper Basin, Australia, and Yanaizu-Nishiyama, Japan. The depth of the reservoir is from 2km to 5km and type of possible slip from the stress state is different for each field. Felt earthquakes have been observed at all the fields with/without clear correlation to human operation to the reservoir. We have estimated fault pale solutions (FPS) of the events using polarization of the first break of P-wave and seismic structure of the hypocenters of the seismic multiplets, and investigated relationship to the other source parameters including magnitude, source radii, and stress drop. The followings have been found throughout this study. (a) Most of the FPSs showed consistency to the Coulomb's criterion for shear slip, suggesting that earthquakes occurred from "highly slip-able" fractures. (b) The data from Cooper Basin showed that most of the felt earthquakes have origin ...

GVM [Gas Verbund Mittelland AG) commissioned in 2011 the acquisition of 113 km of 20 refle ction ... more GVM [Gas Verbund Mittelland AG) commissioned in 2011 the acquisition of 113 km of 20 refle ction seismic as a first step of an integrated exploration campaign for geothermal and hydrocarbon resources in the cantons Nid- and Obwalden [Switzerland). One of the aims of the seismic campaign was to define the structure of the Helvetic nappes and its base, the internal build -up of the underlying Tertiary sediments and the autochthonous Mesozoie cover. The new da ta allow defining the internal tecton ics of the Drusberg nappe and its base. The deformation style of the Drusberg nappe is characterized by imbrication and ramp anticlines . The base of the Helvet ic nappe forms a relatively flat, wide and gently structured synform south of a Une Schwendi - Alpnach - Stans. The base of the Helvetic nappes reaches a max. depth of approximately 1.8-2.0 km below the Sarner Aa valley. It is not possible to distinguish between south dipping Molasse and supposed North Helvetic Flysch . The autochthon...