Joel Le Calvez - Academia.edu (original) (raw)

Papers by Joel Le Calvez

Noise attenuation is a key challenge for surface-acquired microseismic processing. A number of da... more Noise attenuation is a key challenge for surface-acquired microseismic processing. A number of data conditioning tools have been proposed and applied with various degrees of success to improve the signal-to-noise ratio prior to detection and location of microseismic events. Random noise attenuation, trace-by-trace correlation with a large magnitude event, and nonlinear stacking techniques have all been shown individually to improve microseismic event detectability in surface-acquired microseismic datasets. This paper demonstrates how the combination of these approaches significantly increases the number of detected microseismic events while keeping the number of false triggers to a minimum. In particular, random noise attenuation and trace-by-trace correlation with a large magnitude event followed by nonlinear stacking at the stage of substack generation provide a data conditioning workflow that significantly attenuates the effects of statics, anisotropy, and, to some extent, 3D velocity variations. This work is a step towards an optimized data conditioning workflow for surface-acquired microseismic data.

Understanding the created fracture geometry is key to the effectiveness of any stimulation progra... more Understanding the created fracture geometry is key to the effectiveness of any stimulation program, as fracture surface area directly impacts production performance. Microseismic monitoring of hydraulic stimulations can provide in real-time extensive diagnostic information on fracture development and geometry. Thus, it can help with the immediate needs of optimizing the stimulation program for production performance and long-term concerns associated to field development. However, microseismic monitoring is often underutilized at the expense of productivity in the exploration and appraisal phases of a field. Geology is a fundamental element in the design of a stimulation program and the interpretation of its results. Rock properties and geomechanics govern the achievable fracture geometry and influence the type of fluids to be injected in the formation and the pumping schedule. Rock layering controls the location of the monitoring device, guides the depth at which perforations should be located, and influences how hydrocarbons flow within the formation. Despite this importance, the impact geology may have on the stimulation results is often overlooked as it is all too common to see assumed laterally homogeneous formations, invariant stress field (both laterally and vertically), stimulated fractures having a symmetric planar geometry, etc. As exploration and appraisal moves toward active tectonics areas (as opposed to relatively quiet passive margins and depositional basins), understanding the impact of complex geology and the stress field on fracture geometry is critical to optimizing stimulation treatments and establishing robust field development plans. Mapping of hypocenters detected using microseismic monitoring is an ideal tool to help understand near- and far-field fracture geometry. Additionally, moment tensor inversion performed on mapped hypocenters can contribute to understanding the rock failure mechanisms and help with evaluating asymmetric and complex fracture geometry. Understanding this fracture complexity helps address key uncertainties such as achievable fracture coverage of the reservoir. We present the results of several hydraulic fracture stimulations in various geological environments that have been monitored using microseismic data. We illustrate with these case studies that in some rare cases, simple radial and planar fracture system (often mislabeled penny shape-like fracture) may be generated as predicted using simple modeling techniques. However, in most cases, the final fracture system geometry is complex and asymmetric, largely governed by stress, geologic discontinuities, rock fabric, etc. Understanding this impact and optimizing the well design to enhance productivity is key to evaluating reservoir potential and commercial viability during exploration and appraisal phases and for maximizing return on investment during development.

Proceedings, Apr 26, 2010

North American shale-gas recovery efforts are quite large, while the extent of such unconventiona... more North American shale-gas recovery efforts are quite large, while the extent of such unconventional gas reserves in Europe is largely unknown. Some tests of gas shale formations have recently been carried out with good success in various basins (e.g., Germany s Lower Saxony, Vienna Basin, southern Sweden, etc.) The development of Europe s gas resources will take years and may benefit from lessons learned in North America. Firstly production from unconventional shale formations (e.g., Barnett, Fayetteville, Marcellus, Woodford, etc.) has been enabled by modern well log evaluation techniques and completion methods. These are particularly important since stress anisotropy strongly influences fracture system development. Secondly, it is critical to monitor the initiation and evolution of hydraulically-induced fracture systems. Currently almost all predictive models used by reservoir and production engineers to estimate recovery in stimulated wells are based on assumptions that naturally lead to oversimplified fracture geometry. Microseismic monitoring enables reservoir engineers and geoscientists to understand the development of hydraulically-induced fracture systems as well as naturally pre-existing fracture networks in four dimensions.

Proceedings, Mar 27, 2011

Proceedings, Apr 19, 2015

Rigorous processing of microseismic data is essential and indispensable to derive confidently map... more Rigorous processing of microseismic data is essential and indispensable to derive confidently mapped hypocentral locations, as well as associated event attributes and source parameters. Integration with other borehole-based geophysical measurements is key in interpreting formation behavior and properties. In this study, we present the results of a microseismic monitoring campaign performed on multi-stage hydraulic fracturing treatments using two nearby, pseudo-vertical monitoring arrays composed of eight 3-component geophones each. We benefit from several borehole-based geophysical measurements, such as sonic logs, crosswell tomographic and attenuation profiles, and multi-calibration perforation points. Although, all these measurements take place in different frequency domains, together they very efficiently document the variations in space and time of the velocities, anisotropies, attenuations, and rock physics in the zones of interest and surrounding formations. Improved formation evaluation and interpretation during microseismic monitoring allows for improved estimation of reservoir quality and production in hydraulic fracturing treatments and could potentially prove useful in optimizing stage-by-stage stimulation volumes.

The URTeC Technical Program Committee accepted this presentation on the basis of information cont... more The URTeC Technical Program Committee accepted this presentation on the basis of information contained in an abstract submitted by the author(s). The contents of this paper have not been reviewed by URTeC and URTeC does not warrant the accuracy, reliability, or timeliness of any information herein. All information is the responsibility of, and, is subject to corrections by the author(s). Any person or entity that relies on any information obtained from this paper does so at their own risk. The information herein does not necessarily reflect any position of URTeC. Any reproduction, distribution, or storage of any part of this paper without the written consent of URTeC is prohibited.

Second International Meeting for Applied Geoscience & Energy

The attenuation factor (Q) is essential in waveform inversion. This paper presents systematic and... more The attenuation factor (Q) is essential in waveform inversion. This paper presents systematic and quantitative studies of Q on seismic waveforms of different frequencies in waveform inversion. The elastic waveform inversion (without Q update) of data with different Q values results in a slower inverted P-wave velocity and an amplitude decay that cannot match the data. We discuss the importance of the simultaneous viscoelastic inversion of velocity and attenuation.

The leading edge, May 1, 2023

Proceedings, Jun 12, 2017

Proceedings, May 23, 2011

Passive seismic methods which use no active human-build source, but utilise the natural sounds of... more Passive seismic methods which use no active human-build source, but utilise the natural sounds of the earth, produce in most cases a low resolution of the subsurface compared to active seismic. Due to the usually low-frequency content of the earth’s seismic sources, they are often dismissed and not even considered as an add-on for an active-seismic campaign. And this, despite a similar resolution than gravimetric methods, minimal costs compared to an active survey, the same “domain” as active seismics, and their environmental friendliness. The abstract will introduce 6 passive-seismic methods which can be used for hydrocarbon exploration. It will try to rank the different methods and suggest possible applications and integration with active seismic data.

Proceedings, Jun 12, 2017

We have investigated noise estimation in distributed acoustic sensing (DAS). We used an adaptive ... more We have investigated noise estimation in distributed acoustic sensing (DAS). We used an adaptive Wiener filtering method to construct noise maps. The resulting noise maps can be stored together with the images themselves and used in diversity stacks, which provide an uplift in time-lapse repeatability over linear stacking. We found that relatively large gains in VSP repeatability can be made from simple techniques.

Proceedings, 2014

ABSTRACT We have identified individual waveforms from microseismic events and tracked them from r... more ABSTRACT We have identified individual waveforms from microseismic events and tracked them from reservoir to surface using a wide aperture borehole seismic array, as well as across surface seismic lines. We noted that deeper arrivals in the long borehole array contained complex triplications that could potentially pose difficulties for event detection and location techniques that rely on identifying the direct arrivals. By modelling full waveform synthetics we were able to reconstruct the principal features of these complex arrivals for the long borehole array. We have developed an extension to the CMM approach to extract the appropriate arrival times via STA/LTA processing of the full waveform synthetics. These times are then used to augment the first arrival P and S travel times in the objective function used for CMM processing, allowing the energy in complex arrivals to be identified and beam-formed in the event detection algorithm. Mode converted arrivals may also be used in the subsequent Geiger relocation step to provide greater aperture with which to refine the event location.

70th EAGE Conference and Exhibition incorporating SPE EUROPEC 2008, 2008

Microseismic monitoring of hydraulic fracture treatment is commonly carried out without accurate ... more Microseismic monitoring of hydraulic fracture treatment is commonly carried out without accurate deviation surveys of monitoring boreholes. This can lead to significant errors in the observed azimuths and other parameters of the mapped fracture system geometry derived from microseismic event locations. We have developed a new technique to find the horizontal position of the monitoring geophones. This technique uses relative back-azimuths of perforations at known locations. It is particularly suitable for vertical monitoring boreholes and horizontally distributed perforations. It can be combined with travel-time measurements to achieve improved accuracy of the monitoring array positions relative to the perforations (i.e., injection points).

The leading edge, Mar 1, 2011

Real time microseismic monitoring of the growth of the hydraulic fractures in treatment wells, im... more Real time microseismic monitoring of the growth of the hydraulic fractures in treatment wells, implemented in StimMAP system, allows high accuracy direct measurement of frac system geometry (height, length and azimuth) during fracturing as well as obtaining of useful information concerning formation geophysical and geological properties, optimization and planning of further fracturing in the same region. This presentation gives brief review and comparison of existed methods of fracturing monitoring, explains basics of microseismic monitoring and shows case study applications of the method.

69th EAGE Conference and Exhibition incorporating SPE EUROPEC 2007, 2007

Large number of induced events in microseismic datasets requires automated picking of P-and S-wav... more Large number of induced events in microseismic datasets requires automated picking of P-and S-wave arrivals. Furthermore, the automated measurement of the wave arrival times enables , compared to manual processing, fast and repeatable results. However, automatic picking usually suffers from lower accuracy and often only P-wave pickers are being used. We developed a new method for picking P-and S-waves at a linear receiver array, which employs polarization properties and array consistency of the detected phases. The automated method mimics manual picking procedure. We benchmark the automated method on a real micro-seismic dataset by comparison with manual picking. We show that the automated picker is robust as it has found more than 80% of the true arrivals and only 1.5% automatic picks were false alarms. The accuracy of the automated picker measured by standard error of the difference between automatic and manual picks is 1.2 ms for P-and 1.0 ms for S-waves.

In carbon capture and storage projects, and in unconventional plays, microseismic monitoring and ... more In carbon capture and storage projects, and in unconventional plays, microseismic monitoring and optical fiber are critical components of the measure, monitor, and verify value chain. A velocity model is required to estimate source location (hypocenter), source parameters, and source mechanism of a detected microseismic event. Incorrect event locations are often the result of an inaccurate knowledge of the velocity model. We propose a new method to simultaneously invert for the hypocenter and the velocity model to provide a robust long-term microseismic monitoring workflow. Such problem has been studied in several areas of seismology over the last few decades. However, those studies focusing on large-scale earthquakes have remained of limited interest to reservoir-scale applications such as short-term and long-term microseismic monitoring and induced seismic monitoring. In such domains, the integration of sonic log-derived information into the joint inversion problem is critical as the scale is fundamentally different. Our algorithm respects the resolution of sonic measurement, while it calibrates the wavelength where microseismic data have sensitivity: the number of unknown parameters in the velocity model is decoupled from the number of layers included in the model. Therefore, we can solve for the velocity and event location inversion problem in a stable manner while respecting the resolution of the initial velocity model. In the present article, we introduce the science and technique behind the simultaneous inversion for the hypocenter and the velocity model and share case study applications based on a synthetic dataset and a real monitoring campaign.

Noise attenuation is a key challenge for surface-acquired microseismic processing. A number of da... more Noise attenuation is a key challenge for surface-acquired microseismic processing. A number of data conditioning tools have been proposed and applied with various degrees of success to improve the signal-to-noise ratio prior to detection and location of microseismic events. Random noise attenuation, trace-by-trace correlation with a large magnitude event, and nonlinear stacking techniques have all been shown individually to improve microseismic event detectability in surface-acquired microseismic datasets. This paper demonstrates how the combination of these approaches significantly increases the number of detected microseismic events while keeping the number of false triggers to a minimum. In particular, random noise attenuation and trace-by-trace correlation with a large magnitude event followed by nonlinear stacking at the stage of substack generation provide a data conditioning workflow that significantly attenuates the effects of statics, anisotropy, and, to some extent, 3D velocity variations. This work is a step towards an optimized data conditioning workflow for surface-acquired microseismic data.

Understanding the created fracture geometry is key to the effectiveness of any stimulation progra... more Understanding the created fracture geometry is key to the effectiveness of any stimulation program, as fracture surface area directly impacts production performance. Microseismic monitoring of hydraulic stimulations can provide in real-time extensive diagnostic information on fracture development and geometry. Thus, it can help with the immediate needs of optimizing the stimulation program for production performance and long-term concerns associated to field development. However, microseismic monitoring is often underutilized at the expense of productivity in the exploration and appraisal phases of a field. Geology is a fundamental element in the design of a stimulation program and the interpretation of its results. Rock properties and geomechanics govern the achievable fracture geometry and influence the type of fluids to be injected in the formation and the pumping schedule. Rock layering controls the location of the monitoring device, guides the depth at which perforations should be located, and influences how hydrocarbons flow within the formation. Despite this importance, the impact geology may have on the stimulation results is often overlooked as it is all too common to see assumed laterally homogeneous formations, invariant stress field (both laterally and vertically), stimulated fractures having a symmetric planar geometry, etc. As exploration and appraisal moves toward active tectonics areas (as opposed to relatively quiet passive margins and depositional basins), understanding the impact of complex geology and the stress field on fracture geometry is critical to optimizing stimulation treatments and establishing robust field development plans. Mapping of hypocenters detected using microseismic monitoring is an ideal tool to help understand near- and far-field fracture geometry. Additionally, moment tensor inversion performed on mapped hypocenters can contribute to understanding the rock failure mechanisms and help with evaluating asymmetric and complex fracture geometry. Understanding this fracture complexity helps address key uncertainties such as achievable fracture coverage of the reservoir. We present the results of several hydraulic fracture stimulations in various geological environments that have been monitored using microseismic data. We illustrate with these case studies that in some rare cases, simple radial and planar fracture system (often mislabeled penny shape-like fracture) may be generated as predicted using simple modeling techniques. However, in most cases, the final fracture system geometry is complex and asymmetric, largely governed by stress, geologic discontinuities, rock fabric, etc. Understanding this impact and optimizing the well design to enhance productivity is key to evaluating reservoir potential and commercial viability during exploration and appraisal phases and for maximizing return on investment during development.

Proceedings, Apr 26, 2010

North American shale-gas recovery efforts are quite large, while the extent of such unconventiona... more North American shale-gas recovery efforts are quite large, while the extent of such unconventional gas reserves in Europe is largely unknown. Some tests of gas shale formations have recently been carried out with good success in various basins (e.g., Germany s Lower Saxony, Vienna Basin, southern Sweden, etc.) The development of Europe s gas resources will take years and may benefit from lessons learned in North America. Firstly production from unconventional shale formations (e.g., Barnett, Fayetteville, Marcellus, Woodford, etc.) has been enabled by modern well log evaluation techniques and completion methods. These are particularly important since stress anisotropy strongly influences fracture system development. Secondly, it is critical to monitor the initiation and evolution of hydraulically-induced fracture systems. Currently almost all predictive models used by reservoir and production engineers to estimate recovery in stimulated wells are based on assumptions that naturally lead to oversimplified fracture geometry. Microseismic monitoring enables reservoir engineers and geoscientists to understand the development of hydraulically-induced fracture systems as well as naturally pre-existing fracture networks in four dimensions.

Proceedings, Mar 27, 2011

Proceedings, Apr 19, 2015

Rigorous processing of microseismic data is essential and indispensable to derive confidently map... more Rigorous processing of microseismic data is essential and indispensable to derive confidently mapped hypocentral locations, as well as associated event attributes and source parameters. Integration with other borehole-based geophysical measurements is key in interpreting formation behavior and properties. In this study, we present the results of a microseismic monitoring campaign performed on multi-stage hydraulic fracturing treatments using two nearby, pseudo-vertical monitoring arrays composed of eight 3-component geophones each. We benefit from several borehole-based geophysical measurements, such as sonic logs, crosswell tomographic and attenuation profiles, and multi-calibration perforation points. Although, all these measurements take place in different frequency domains, together they very efficiently document the variations in space and time of the velocities, anisotropies, attenuations, and rock physics in the zones of interest and surrounding formations. Improved formation evaluation and interpretation during microseismic monitoring allows for improved estimation of reservoir quality and production in hydraulic fracturing treatments and could potentially prove useful in optimizing stage-by-stage stimulation volumes.

The URTeC Technical Program Committee accepted this presentation on the basis of information cont... more The URTeC Technical Program Committee accepted this presentation on the basis of information contained in an abstract submitted by the author(s). The contents of this paper have not been reviewed by URTeC and URTeC does not warrant the accuracy, reliability, or timeliness of any information herein. All information is the responsibility of, and, is subject to corrections by the author(s). Any person or entity that relies on any information obtained from this paper does so at their own risk. The information herein does not necessarily reflect any position of URTeC. Any reproduction, distribution, or storage of any part of this paper without the written consent of URTeC is prohibited.

Second International Meeting for Applied Geoscience & Energy

The attenuation factor (Q) is essential in waveform inversion. This paper presents systematic and... more The attenuation factor (Q) is essential in waveform inversion. This paper presents systematic and quantitative studies of Q on seismic waveforms of different frequencies in waveform inversion. The elastic waveform inversion (without Q update) of data with different Q values results in a slower inverted P-wave velocity and an amplitude decay that cannot match the data. We discuss the importance of the simultaneous viscoelastic inversion of velocity and attenuation.

The leading edge, May 1, 2023

Proceedings, Jun 12, 2017

Proceedings, May 23, 2011

Passive seismic methods which use no active human-build source, but utilise the natural sounds of... more Passive seismic methods which use no active human-build source, but utilise the natural sounds of the earth, produce in most cases a low resolution of the subsurface compared to active seismic. Due to the usually low-frequency content of the earth’s seismic sources, they are often dismissed and not even considered as an add-on for an active-seismic campaign. And this, despite a similar resolution than gravimetric methods, minimal costs compared to an active survey, the same “domain” as active seismics, and their environmental friendliness. The abstract will introduce 6 passive-seismic methods which can be used for hydrocarbon exploration. It will try to rank the different methods and suggest possible applications and integration with active seismic data.

Proceedings, Jun 12, 2017

We have investigated noise estimation in distributed acoustic sensing (DAS). We used an adaptive ... more We have investigated noise estimation in distributed acoustic sensing (DAS). We used an adaptive Wiener filtering method to construct noise maps. The resulting noise maps can be stored together with the images themselves and used in diversity stacks, which provide an uplift in time-lapse repeatability over linear stacking. We found that relatively large gains in VSP repeatability can be made from simple techniques.

Proceedings, 2014

ABSTRACT We have identified individual waveforms from microseismic events and tracked them from r... more ABSTRACT We have identified individual waveforms from microseismic events and tracked them from reservoir to surface using a wide aperture borehole seismic array, as well as across surface seismic lines. We noted that deeper arrivals in the long borehole array contained complex triplications that could potentially pose difficulties for event detection and location techniques that rely on identifying the direct arrivals. By modelling full waveform synthetics we were able to reconstruct the principal features of these complex arrivals for the long borehole array. We have developed an extension to the CMM approach to extract the appropriate arrival times via STA/LTA processing of the full waveform synthetics. These times are then used to augment the first arrival P and S travel times in the objective function used for CMM processing, allowing the energy in complex arrivals to be identified and beam-formed in the event detection algorithm. Mode converted arrivals may also be used in the subsequent Geiger relocation step to provide greater aperture with which to refine the event location.

70th EAGE Conference and Exhibition incorporating SPE EUROPEC 2008, 2008

Microseismic monitoring of hydraulic fracture treatment is commonly carried out without accurate ... more Microseismic monitoring of hydraulic fracture treatment is commonly carried out without accurate deviation surveys of monitoring boreholes. This can lead to significant errors in the observed azimuths and other parameters of the mapped fracture system geometry derived from microseismic event locations. We have developed a new technique to find the horizontal position of the monitoring geophones. This technique uses relative back-azimuths of perforations at known locations. It is particularly suitable for vertical monitoring boreholes and horizontally distributed perforations. It can be combined with travel-time measurements to achieve improved accuracy of the monitoring array positions relative to the perforations (i.e., injection points).

The leading edge, Mar 1, 2011

Real time microseismic monitoring of the growth of the hydraulic fractures in treatment wells, im... more Real time microseismic monitoring of the growth of the hydraulic fractures in treatment wells, implemented in StimMAP system, allows high accuracy direct measurement of frac system geometry (height, length and azimuth) during fracturing as well as obtaining of useful information concerning formation geophysical and geological properties, optimization and planning of further fracturing in the same region. This presentation gives brief review and comparison of existed methods of fracturing monitoring, explains basics of microseismic monitoring and shows case study applications of the method.

69th EAGE Conference and Exhibition incorporating SPE EUROPEC 2007, 2007

Large number of induced events in microseismic datasets requires automated picking of P-and S-wav... more Large number of induced events in microseismic datasets requires automated picking of P-and S-wave arrivals. Furthermore, the automated measurement of the wave arrival times enables , compared to manual processing, fast and repeatable results. However, automatic picking usually suffers from lower accuracy and often only P-wave pickers are being used. We developed a new method for picking P-and S-waves at a linear receiver array, which employs polarization properties and array consistency of the detected phases. The automated method mimics manual picking procedure. We benchmark the automated method on a real micro-seismic dataset by comparison with manual picking. We show that the automated picker is robust as it has found more than 80% of the true arrivals and only 1.5% automatic picks were false alarms. The accuracy of the automated picker measured by standard error of the difference between automatic and manual picks is 1.2 ms for P-and 1.0 ms for S-waves.

In carbon capture and storage projects, and in unconventional plays, microseismic monitoring and ... more In carbon capture and storage projects, and in unconventional plays, microseismic monitoring and optical fiber are critical components of the measure, monitor, and verify value chain. A velocity model is required to estimate source location (hypocenter), source parameters, and source mechanism of a detected microseismic event. Incorrect event locations are often the result of an inaccurate knowledge of the velocity model. We propose a new method to simultaneously invert for the hypocenter and the velocity model to provide a robust long-term microseismic monitoring workflow. Such problem has been studied in several areas of seismology over the last few decades. However, those studies focusing on large-scale earthquakes have remained of limited interest to reservoir-scale applications such as short-term and long-term microseismic monitoring and induced seismic monitoring. In such domains, the integration of sonic log-derived information into the joint inversion problem is critical as the scale is fundamentally different. Our algorithm respects the resolution of sonic measurement, while it calibrates the wavelength where microseismic data have sensitivity: the number of unknown parameters in the velocity model is decoupled from the number of layers included in the model. Therefore, we can solve for the velocity and event location inversion problem in a stable manner while respecting the resolution of the initial velocity model. In the present article, we introduce the science and technique behind the simultaneous inversion for the hypocenter and the velocity model and share case study applications based on a synthetic dataset and a real monitoring campaign.