Magnitude SAS

Sainte-Tulle, France

Magnitude SAS

Sainte-Tulle, France
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Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2012-ITN | Award Amount: 4.16M | Year: 2013

The FlowTrans Initial Training Network is a unique environment for career development, built on joint challenges of Industry and University partners in a newly emerging supra-disciplinary field, spanning from Physics to Earth Sciences and aiming to understand Flow in Transforming Porous Media. Training will be hosted by 8 Universities in synergy with 2 full and 4 associated industry partners with the objective of delivering highly-trained mobile researchers to the European market. The objective of FlowTrans is the creation of a unique research training environment and a new inter-sectoral supra-interdisciplinary field to de-fragment European knowledge and combine industry and universities to harness understanding of basic scientific questions for tackling future challenges in Exploration of Geological Resources. Our research training objectives focus on teaching ESRs and ERs the necessary interdisciplinary skills needed to study Flow in Transforming Porous Media. The characterization and the understanding of flow of fluids within rocks and granular media has become an ever-increasing problem in Earth Sciences, Physics, and in many industrial applications, including CO2 sequestration, hydrocarbon migration, ore deposit development, and radioactive waste disposal. One of the main problems is the understanding of flows in transforming porous media (PM), where the rocks and fluid pathways evolve spatially and temporally, for example due to chemical interactions with the flow, or due to compaction of the solid matrix. We propose to study the feedback mechanisms and their impact on the porous media through an interdisciplinary approach between Earth Scientists and Physicists. State of the art analytical and experimental methods will be used on natural systems and rock analogues, and will be complemented by multi-scale dynamical simulations, to develop new basic understanding and new methods that can be directly used in industrial applications.

Rosca A.,Magnitude SAS | Maisons C.,Magnitude SAS
Society of Petroleum Engineers - SPE/EAGE European Unconventional Resources Conference and Exhibition 2012 | Year: 2012

Monitoring reservoir Stimulation operations provides data for predicting production performance and for reservoir characterization but also, potentially, for compliance with local regulations. With improved drilling and completion technology the depth of the unconventional reservoirs produced increases and the options for deploying cost-effective microseismic monitoring equipment become limited. The monitoring technology has to adapt by optimizing acquisition geometry and data processing as well as the procedures that demonstrate the validity of me results. A practical solution for microseismic monitoring of stimulation operations in an unconventional reservoir under development is a surface or shallow distributed array. We are analyzing three such datasets together with complementary deep borehole sensor datasets to understand how to predict and validate the expected performance of distributed surface and shallow arrays. The surface recorded data is processed by stacking and event detection and location are accepted based on statistical criteria. This catalog of events is compared to the one obtained from borehole array where waveforms can be analyzed individually in order to validate the quality of event analysis. Copyright 2012, Society of Petroleum Engineers.

Godano M.,University of Nice Sophia Antipolis | Godano M.,Magnitude S.A.S. | Gaucher E.,Magnitude S.A.S. | Bardainne T.,Magnitude S.A.S. | And 3 more authors.
Geophysical Prospecting | Year: 2010

We have developed a method that enables computing double-couple focal mechanisms with only a few sensors. This method is based on a non-linear inversion of the P, Sv and Sh amplitudes of microseismic events recorded on a set of sensors. The information brought by the focal mechanism enables determining the geometry of the rupture on the associated geological structure. It also provides a better estimate of the conventional source parameters. Full analysis has been performed on a data set of 15 microseismic events recorded in the brine production field of Vauvert. The microseismic monitoring network consisted of two permanent tools and one temporary borehole string. The majority of the focal mechanisms computed from both permanent tools are similar to those computed from the whole network. This result indicates that the double-couple focal mechanism determination is reliable for both permanent 3C receivers in this field. © 2010 European Association of Geoscientists & Engineers.

Gesret A.,MINES ParisTech | Desassis N.,MINES ParisTech | Noble M.,MINES ParisTech | Romary T.,MINES ParisTech | Maisons C.,Magnitude SAS
Geophysical Journal International | Year: 2015

Earthquake hypocentre locations are crucial in many domains of application (academic and industrial) as seismic event location maps are commonly used to delineate faults or fractures. The interpretation of these maps depends on location accuracy and on the reliability of the associated uncertainties. The largest contribution to location and uncertainty errors is due to the fact that the velocity model errors are usually not correctly taken into account. We propose a new Bayesian formulation that integrates properly the knowledge on the velocity model into the formulation of the probabilistic earthquake location. In this work, the velocity model uncertainties are first estimated with a Bayesian tomography of active shot data. We implement a sampling Monte Carlo type algorithm to generate velocity models distributed according to the posterior distribution. In a second step, we propagate the velocity model uncertainties to the seismic event location in a probabilistic framework. This enables to obtain more reliable hypocentre locations as well as their associated uncertainties accounting for picking and velocity model uncertainties. We illustrate the tomography results and the gain in accuracy of earthquake location for two synthetic examples and one real data case study in the context of induced microseismicity. © The Authors 2014. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Belayouni N.,Magnitude SAS | Gesret A.,MINES ParisTech | Daniel G.,Magnitude SAS | Noble M.,MINES ParisTech
Geophysics | Year: 2015

Locating microseismic events accurately is essential to characterizing hydrofracked reservoirs. Several location approaches have been developed to solve this problem. We have developed a global grid search method based on the Bayesian probabilistic approach. In addition to retrieving the global minimum of the cost function, it enabled the computation of the uncertainty that was essential to quantify the quality of the results. The location uncertainty was tightly related to the amount and the quality of observed data used to perform the location. Using multiple arrivals increased the quantity of information collected in a cost-effective manner (no additional receivers were required). In this location algorithm, we have used the first and reflected arrivals to constrain the locations. To locate the events, it was essential to model the first and reflected arrivals given a velocity model and acquisition geometry. We have developed a ray-tracing algorithm capable of computing traveltimes and polarization of direct, refracted, reflected waves in layered velocity models. We have applied this methodology for several examples. The synthetic data set was generated using full-waveform finite-difference modeling and recorded in a single vertical well. The first and reflected traveltimes were picked using the 3C seismograms. In the last example, we used the Cotton Valley real data set in which reflections could be seen for strong events due to the high velocity contrasts. The applications revealed that the location uncertainty was significantly reduced when using both arrivals compared with the case when only first arrivals were used. Combining the first and reflected arrivals even allowed us to improve the location accuracy when the velocity model was inaccurate. © 2015 Society of Exploration Geophysicists.

Bottero A.,MINES ParisTech | Bottero A.,Aix - Marseille University | Gesret A.,MINES ParisTech | Romary T.,MINES ParisTech | And 2 more authors.
Geophysical Journal International | Year: 2016

Markov chain Monte Carlo sampling methods are widely used for non-linear Bayesian inversionwhere no analytical expression for the forward relation between data and model parameters is available. Contrary to the linear(ized) approaches, they naturally allow to evaluate the uncertainties on the model found. Nevertheless their use is problematic in high-dimensional model spaces especially when the computational cost of the forward problem is significant and/or the a posteriori distribution is multimodal. In this case, the chain can stay stuck in one of the modes and hence not provide an exhaustive sampling of the distribution of interest. We present here a still relatively unknown algorithm that allows interaction between several Markov chains at different temperatures. These interactions (based on importance resampling) ensure a robust sampling of any posterior distribution and thus provide a way to efficiently tackle complex fully non-linear inverse problems. The algorithm is easy to implement and is well adapted to run on parallel supercomputers. In this paper, the algorithm is first introduced and applied to a synthetic multimodal distribution in order to demonstrate its robustness and efficiency compared to a simulated annealing method. It is then applied in the framework of first arrival traveltime seismic tomography on real data recorded in the context of hydraulic fracturing. To carry out this study a wavelet-based adaptive model parametrization has been used. This allows to integrate the a priori information provided by sonic logs and to reduce optimally the dimension of the problem. © The Authors 2016.

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