arXiv: Geophysics最新文献_第6页

Joint Seismic Data Denoising and Interpolation with Double-Sparsity Dictionary Learning 基于双稀疏字典学习的联合地震数据去噪与插值

arXiv: Geophysics Pub Date : 2017-03-07 DOI: 10.1088/1742-2140/aa6491

Lingchen Zhu, E. Liu, J. McClellan

{"title":"Joint Seismic Data Denoising and Interpolation with Double-Sparsity Dictionary Learning","authors":"Lingchen Zhu, E. Liu, J. McClellan","doi":"10.1088/1742-2140/aa6491","DOIUrl":"https://doi.org/10.1088/1742-2140/aa6491","url":null,"abstract":"Seismic data quality is vital to geophysical applications, so methods of data recovery, including denoising and interpolation, are common initial steps in the seismic data processing flow. We present a method to perform simultaneous interpolation and denoising, which is based on double-sparsity dictionary learning. This extends previous work that was for denoising only. The original double sparsity dictionary learning algorithm is modified to track the traces with missing data by defining a masking operator that is integrated into the sparse representation of the dictionary. A weighted low-rank approximation algorithm is adopted to handle the dictionary updating as a sparse recovery optimization problem constrained by the masking operator. Compared to traditional sparse transforms with fixed dictionaries that lack the ability to adapt to complex data structures, the double-sparsity dictionary learning method learns the signal adaptively from selected patches of the corrupted seismic data while preserving compact forward and inverse transform operators. Numerical experiments on synthetic seismic data indicate that this new method preserves more subtle features in the dataset without introducing pseudo-Gibbs artifacts when compared to other directional multiscale transform methods such as curvelets.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130813460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 38

A homopolar disc dynamo experiment with liquid metal contacts 液态金属触点的同极圆盘发电机实验

arXiv: Geophysics Pub Date : 2017-02-27 DOI: 10.22364/mhd.53.2.13

R. Avalos-Zuniga, J. Priede, C. E. Bello-Morales

{"title":"A homopolar disc dynamo experiment with liquid metal contacts","authors":"R. Avalos-Zuniga, J. Priede, C. E. Bello-Morales","doi":"10.22364/mhd.53.2.13","DOIUrl":"https://doi.org/10.22364/mhd.53.2.13","url":null,"abstract":"We present experimental results of a homopolar disc dynamo constructed at CICATA-Queretaro in Mexico. The device consists of a flat, multi-arm spiral coil which is placed above a fast-spinning metal disc and connected to the latter by sliding liquid-metal electrical contacts. Theoretically, self-excitation of the magnetic field is expected at the critical magnetic Reynolds number Rm~45, which corresponds to a critical rotation rate of about 10 Hz. We measured the magnetic field above the disc and the voltage drop on the coil for the rotation rate up to 14 Hz, at which the liquid metal started to leak from the outer sliding contact. Instead of the steady magnetic field predicted by the theory we detected a strongly fluctuating magnetic field with a strength comparable to that of Earth's magnetic field which was accompanied by similar voltage fluctuations in the coil. These fluctuations seem to be caused by the intermittent electrical contact through the liquid metal. The experimental results suggest that the dynamo with the actual electrical resistance of liquid metal contacts could be excited at the rotation rate of around 21 Hz provided that the leakage of liquid metal is prevented.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133181063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Particle velocity based hydrofracturing algorithm for a penny-shaped crack 基于粒子速度的便士型裂缝水力压裂算法

arXiv: Geophysics Pub Date : 2016-12-10 DOI: 10.1007/s11012-018-0903-6, 10.1007/s11012-018-0899-y

D. Peck, M. Wrobel, Monika Perkowska, Gennady Mishuris

引用次数: 0

Spatiotemporal Structure of Aeolian Particle Transport on Flat Surface 平坦表面风成粒子输运的时空结构

arXiv: Geophysics Pub Date : 2016-09-08 DOI: 10.7566/JPSJ.86.054402

H. Niiya, K. Nishimura

{"title":"Spatiotemporal Structure of Aeolian Particle Transport on Flat Surface","authors":"H. Niiya, K. Nishimura","doi":"10.7566/JPSJ.86.054402","DOIUrl":"https://doi.org/10.7566/JPSJ.86.054402","url":null,"abstract":"We conduct numerical simulations based on a model of blowing snow to reveal the long-term properties and equilibrium state of aeolian particle transport from $10^{-5} hspace{0.5 ex} mathrm{m}$ to $10 hspace{0.5 ex} mathrm{m}$ above the flat surface. The numerical results are as follows. (i) Time-series data of particle transport are divided into development, relaxation, and equilibrium phases, which are formed by rapid wind response below $10 hspace{0.5 ex} mathrm{cm}$ and gradual wind response above $10 hspace{0.5 ex} mathrm{cm}$. (ii) The particle transport rate at equilibrium is expressed as a power function of friction velocity, and the index of 2.35 implies that most particles are transported by saltation. (iii) The friction velocity below $100 hspace{0.5 ex} mumathrm{m}$ remains roughly constant and lower than the fluid threshold at equilibrium. (iv) The mean particle speed above $300 hspace{0.5 ex} mumathrm{m}$ is less than the wind speed, whereas that below $300 hspace{0.5 ex} mumathrm{m}$ exceeds the wind speed because of descending particles. (v) The particle diameter increases with height in the saltation layer, and the relationship is expressed as a power function. Through comparisons with the previously reported random-flight model, we find a crucial problem that empirical splash functions cannot reproduce particle dynamics at a relatively high wind speed.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121023951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Blade-shaped (PKN) Hydraulic Fracture Driven By A Turbulent Fluid In An Impermeable Rock 不透水岩石中紊流驱动的叶片型水力裂缝

arXiv: Geophysics Pub Date : 2016-09-05 DOI: 10.1061/(ASCE)EM.1943-7889.0001350

N. Zolfaghari, C. Meyer, A. Bunger

{"title":"Blade-shaped (PKN) Hydraulic Fracture Driven By A Turbulent Fluid In An Impermeable Rock","authors":"N. Zolfaghari, C. Meyer, A. Bunger","doi":"10.1061/(ASCE)EM.1943-7889.0001350","DOIUrl":"https://doi.org/10.1061/(ASCE)EM.1943-7889.0001350","url":null,"abstract":"High flow rate, water-driven hydraulic fractures are more common now than ever in the oil and gas industry. Although the fractures are small, the high injection rate and low viscosity of the water, lead to high Reynolds numbers and potentially turbulence in the fracture. Here we present a semi-analytical solution for a blade-shaped (PKN) geometry hydraulic fracture driven by a turbulent fluid in the limit of zero fluid leak-off to the formation. We model the turbulence in the PKN fracture using the Gaukler-Manning-Strickler parametrization, which relates the the flow rate of the water to the pressure gradient along the fracture. The key parameter in this relation is the Darcy-Weisbach friction factor for the roughness of the crack wall. Coupling this turbulence parametrization with conservation of mass allows us to write a nonlinear pde for the crack width as a function of space and time. By way of a similarity ansatz, we obtain a semi-analytical solution using an orthogonal polynomial series. Embedding the asymptotic behavior near the fracture tip into the polynomial series, we find very rapid convergence: a suitably accurate solution is obtained with two terms of the series. This closed-form solution facilitates clear comparisons between the results and parameters for laminar and turbulent hydraulic fractures. In particular, it resolves one of the well known problems whereby calibration of models to data has difficulty simultaneously matching the hydraulic fracture length and wellbore pressure.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130020445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 14

Modelling Geomechanical Impact of CO2 Injection and Migration Using Precomputed Response Functions 利用预先计算的响应函数模拟CO2注入和运移的地质力学影响

arXiv: Geophysics Pub Date : 2016-08-29 DOI: 10.3997/2214-4609.201601760

O. Andersen, H. Nilsen, S. Gasda

{"title":"Modelling Geomechanical Impact of CO2 Injection and Migration Using Precomputed Response Functions","authors":"O. Andersen, H. Nilsen, S. Gasda","doi":"10.3997/2214-4609.201601760","DOIUrl":"https://doi.org/10.3997/2214-4609.201601760","url":null,"abstract":"When injecting CO2 or other fluids into a geological formation, pressure plays an important role both as a driver of flow and as a risk factor for mechanical integrity. The full effect of geomechanics on aquifer flow can only be captured using a coupled flow-geomechanics model. In order to solve this computationally expensive system, various strategies have been put forward over the years, with some of the best current methods based on sequential splitting. In this present work, we seek to approximate the full geomechanics effect on flow without the need of coupling with a geomechanics solver during simulation. We do this by means of precomputed pressure response functions. At grid model generation time, a geomechanics solver is used to compute the mechanical response of the aquifer for a set of pressure fields. The relevant information from these responses is then stored in a compact form and embedded with the grid model. We test the accuracy and computational performance of our approach on a simple 2D model and a more complex 3D model, and compare the results with those produced by a fully coupled approach as well as from as simple decoupled method based on Geertsma's uniaxial expansion coefficient.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131678357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Convection-driven kinematic dynamos at low Rossby and magnetic Prandtl numbers 低罗斯比数和磁普朗特数下对流驱动的运动学发电机

arXiv: Geophysics Pub Date : 2016-07-28 DOI: 10.1103/PhysRevFluids.1.083701

M. Calkins, Louie Long, D. Nieves, K. Julien, S. Tobias

{"title":"Convection-driven kinematic dynamos at low Rossby and magnetic Prandtl numbers","authors":"M. Calkins, Louie Long, D. Nieves, K. Julien, S. Tobias","doi":"10.1103/PhysRevFluids.1.083701","DOIUrl":"https://doi.org/10.1103/PhysRevFluids.1.083701","url":null,"abstract":"Most large-scale planetary magnetic fields are thought to be driven by low Rossby number convection of a low magnetic Prandtl number fluid. Here kinematic dynamo action is investigated with an asymptotic, rapidly rotating dynamo model for the plane layer geometry that is intrinsically low magnetic Prandtl number. The thermal Prandtl number and Rayleigh number are varied to illustrate fundamental changes in flow regime, ranging from laminar cellular convection to geostrophic turbulence in which an inverse energy cascade is present. A decrease in the efficiency of the convection to generate a dynamo, as determined by an increase in the critical magnetic Reynolds number, is observed as the buoyancy forcing is increased. This decreased efficiency may result from both the loss of correlations associated with the increasingly disordered states of flow that are generated, and boundary layer behavior that enhances magnetic diffusion locally. We find that the spatial characteristics of $alpha$, and thus the large-scale magnetic field, is dependent only weakly on changes in flow behavior. However, our results are limited to the linear, kinematic dynamo regime, and future simulations including the Lorentz force are therefore necessary to assess the robustness of this result. In contrast to the large-scale magnetic field, the behavior of the small-scale magnetic field is directly dependent on, and therefore shows significant variations with, the small-scale convective flow field.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116185665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 17

Separating Simultaneous Seismic Sources using Robust Inversion of Radon and Migration Operators 利用Radon和偏移算子鲁棒反演分离同步震源

arXiv: Geophysics Pub Date : 2016-06-01 DOI: 10.7939/R3SB3X886

Amr Ibrahim

{"title":"Separating Simultaneous Seismic Sources using Robust Inversion of Radon and Migration Operators","authors":"Amr Ibrahim","doi":"10.7939/R3SB3X886","DOIUrl":"https://doi.org/10.7939/R3SB3X886","url":null,"abstract":"The advent of high density 3D wide azimuth survey configurations has greatly increased the cost of seismic acquisition. Simultaneous source acquisition presents an opportunity to decrease costs by reducing the survey time. Source time delays are typically long enough for seismic reflection energy to decay to negligible levels before firing another source. Simultaneous source acquisition abandons this minimum time restriction and allows interference between seismic sources to compress the survey time. Seismic data processing methods must address the interference introduced by simultaneous overlapping sources. Simultaneous source data are characterized by high amplitude interference artefacts that may be stronger than the primary signal. These large amplitudes are due to the time delay between sources and the rapid decay of seismic energy with arrival time. Therefore, source interference will appear as outliers in denoising algorithms that make use of a Radon transform. This will reduce the accuracy of Radon transform de-noising especially for weak signals. Formulating the Radon transform as an inverse problem with an L1 misfit makes it robust to outliers caused by source interference. This provides the ability to attenuate strong source interference while preserving weak underlying signal. In order to improve coherent signal focusing, an apex shifted hyperbolic Radon transform (ASHRT) is used to remove source interferences. ASHRT transform basis functions are tailored to match the travel time hyperbolas of reflections in common receiver gathers. However, the ASHRT transform has a high computational cost due to the extension of the model dimensions by scanning for apex locations. By reformulating the ASHRT operator using a Stolt migration/demigration kernel that exploits the Fast Fourier Transform (FFT), the computational efficiency of the operator is drastically improved.","PeriodicalId":390991,"journal":{"name":"arXiv: Geophysics","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125612478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

Wave Propagation in Porous Elastoplastic Rocks: Implication for Seismic Attenuation. 波在多孔弹塑性岩石中的传播:对地震衰减的启示。

arXiv: Geophysics Pub Date : 2016-05-31 DOI: 10.3997/2214-4609.201601055

V. Yarushina, A. Minakov

引用次数: 2

Methods for Analyzing Surface Texture Effects of Volcanoes with Plinian and Subplinian Eruptions Types: Cases of Study Lascar (23° 22' S) and Chaiten (42 ° 50' S), Chile Plinian和Subplinian喷发类型火山表面纹理效应分析方法——以智利Lascar(23°22’S)和Chaiten(42°50’S)为例

arXiv: Geophysics Pub Date : 2016-05-25 DOI: 10.20944/PREPRINTS201806.0132.V1

L. Fernandez, G. Álvarez, R. Salinas

引用次数: 1