Interpretation of the tilt response of two tiltmeters to water injection into a tar sands formation

1992 ◽  
Vol 29 (3) ◽  
pp. 516-521
Author(s):  
F. W. Jones ◽  
F. Pascal ◽  
J. S. Rogers
Keyword(s):  
Key Words ◽  
Mercury Level ◽  
Water Injection ◽  
Inversion Method ◽  
Nonlinear Inversion ◽  
Near Surface ◽  
Tar Sands ◽  
Response Enhancement ◽  
Tilt Response ◽  
Fracture Growth

Near-surface tilt associated with fracture growth caused by water injection into a tar sands formation during an 18-day period was monitored by two biaxial mercury-level borehole tiltmeters. A nonlinear inversion method has been used to determine the fracture dimensions and position of its centre for five data groups from within that time. The inversion is limited by having data from only two tiltmeters, and a horizontal rectangular fracture must be assumed. The fracture expands rapidly initially, and more slowly as time progresses. The area of the fracture increases from approximately 5000 to about 240 000 m2 during the 18 days of injection and its centre migrates approximately 50 m. Key words : tiltmeters, tilt response, enhancement monitoring.

Near-surface tilt response to steam injection into a tar sands formation

1990 ◽  
Vol 27 (10) ◽  
pp. 1312-1315 ◽  
Author(s):  
J. S. Rogers ◽  
F. W. Jones ◽  
M. E. Ertman ◽  
J. Thibault
Keyword(s):  
Hydraulic Fracture ◽  
Mercury Level ◽  
Steam Injection ◽  
Injection Well ◽  
Near Surface ◽  
Tar Sands ◽  
Injection Process ◽  
Tilt Response ◽  
Fast Fracture

Two biaxial mercury-level borehole tiltmeters located at moderate depth (20 m) and 91 m horizontally distant from the injection well have been used to monitor the effects of a fast hydraulic fracture and subsequent steam injection in a tar sands formation at a depth of 230 m. Tilt vectors are determined for the maximum tilts during the fracture, and the long-term tilt migration associated with the steam-injection process is monitored. The tilt associated with the fast fracture is of the order of 1–2 μrad, and the long-term tilt increased as much as 240 μrad over the 500 day monitoring period, and appeared to approach a limit. The long-term tilt migration generally follows the same orientation as the initial tilt due to the fast fracture.

Exploiting surface consistency for surface-wave characterization and mitigation — Part 2: Application to 3D data

Geophysics ◽  
2017 ◽  
Vol 82 (1) ◽  
pp. V39-V50 ◽  
Author(s):  
Christine E. Krohn ◽  
Partha S. Routh
Keyword(s):  
Surface Wave ◽  
Low Frequency ◽  
Single Mode ◽  
Complex Surface ◽  
Surface Elevation ◽  
Inversion Method ◽  
Model Parameters ◽  
Nonlinear Inversion ◽  
Data Set ◽  
Near Surface

We present a case history demonstrating the 3D implementation of the surface-wave impulse estimation and removal (SWIPER) method. SWIPER is a tomographic inversion method that is able to predict and remove complex surface waves, which are multimodal and heterogeneous. The inversion generates surface-consistent model parameters, which correlate with near-surface elevation. These parameters include a surface map of the propagation velocity and attenuation values for each surface-wave mode as a function of frequency. The method also determines variations in source coupling as a function of frequency, which also correlate with the near-surface elevation changes. We show that the method works equally well with a fully sampled and decimated 3D dynamite-sourced data set. We start with a linear single-mode inversion and use the results to generate the starting model for a subsequent three-mode nonlinear inversion. The resulting velocity-dispersion grid has greater lateral resolution and extends to higher frequencies than that generated by a conventional array beam forming method. The propagation and source coupling parameters can be used together to predict the surface-wave waveforms, which are then adaptively subtracted from the data on a trace-to-trace basis. We demonstrate with decimated data that low-frequency reflections can be preserved, even when the data are highly aliased and would be removed by traditional multichannel filters.

Nonlinear velocity inversion by a two‐step Monte Carlo method.

Geophysics ◽  
1994 ◽  
Vol 59 (4) ◽  
pp. 577-590 ◽  
Author(s):  
Side Jin ◽  
Raul Madariaga
Keyword(s):  
Monte Carlo ◽  
Velocity Model ◽  
Small Scale ◽  
Inversion Method ◽  
Nonlinear Inversion ◽  
Ray Theory ◽  
Data Set ◽  
Seismic Reflection Data ◽  
Velocity Models ◽  
Reference Velocity

Seismic reflection data contain information on small‐scale impedance variations and a smooth reference velocity model. Given a reference velocity model, the reflectors can be obtained by linearized migration‐inversion. If the reference velocity is incorrect, the reflectors obtained by inverting different subsets of the data will be incoherent. We propose to use the coherency of these images to invert for the background velocity distribution. We have developed a two‐step iterative inversion method in which we separate the retrieval of small‐scale variations of the seismic velocity from the longer‐period reference velocity model. Given an initial background velocity model, we use a waveform misfit‐functional for the inversion of small‐scale velocity variations. For this linear step we use the linearized migration‐inversion method based on ray theory that we have recently developed with Lambaré and Virieux. The reference velocity model is then updated by a Monte Carlo inversion method. For the nonlinear inversion of the velocity background, we introduce an objective functional that measures the coherency of the short wavelength components obtained by inverting different common shot gathers at the same locations. The nonlinear functional is calculated directly in migrated data space to avoid expensive numerical forward modeling by finite differences or ray theory. Our method is somewhat similar to an iterative migration velocity analysis, but we do an automatic search for relatively large‐scale 1-D reference velocity models. We apply the nonlinear inversion method to a marine data set from the North Sea and also show that nonlinear inversion can be applied to realistic scale data sets to obtain a laterally heterogeneous velocity model with a reasonable amount of computer time.

scholarly journals Estimation of the Rupture History of the 2008 Mw8.0 Wenchuan Earthquake by Joint Inversion of Teleseismic and Strong-Motion Records

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Deyu Yin ◽  
Yun Dong ◽  
Qifang Liu ◽  
Yuexin She ◽  
Jingke Wu ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Strong Motion ◽  
Inversion Method ◽  
Near Surface ◽  
Strong Motion Records ◽  
The Wenchuan Earthquake ◽  
Finite Fault ◽  
History Of ◽  
Beichuan Fault ◽  
Dip Angle

In order to reproduce the rupture history of the 2008 Mw8.0 Wenchuan earthquake, the teleseismic and strong-motion records are adopted. Based on a multiple-segment, variable-slip model, the finite fault inversion method is utilized to recover the rupture process. The results are as follows: (1) the rupture duration of the Wenchuan earthquake is about 100 s, and the released seismic moment is 1.24 × 1021 N·m, equal to the moment magnitude Mw8.0. There are 5 asperities on the fault plane, indicating that the earthquake is composed of at least 5 subevents. (2) The slip is mainly distributed on the Beichuan fault, indicating that the Beichuan fault is the main rupture fault. On the southern part of the Beichuan fault, the dislocation underside the Longmenshan area and Hongkou-Yingxiu near-surface area is dominated by thrust, and the maximum slip is 11.8 m. Slip between the Yuejiashan and Qingping area is dominated by thrust. On the northern part of the Beichuan fault, the area under Beichuan is dominated by thrust, the slip under Nanba is thrust and strike, near Qingchuan, the slip turns into the strike slip, and the maximum slip is 13.1 m. The dislocation under Bailu is also dominated by thrust, with maximum slip 8.9 m. (3) The rupture of the Wenchuan earthquake is mainly a unilateral rupture to the northeast. The rupture started at the low dip angle part of the Beichuan fault, and after 3 s, it propagated to the Pengguan fault. After 10 s, the largest asperity under Longmenshan in the south section of the Beichuan fault began to break, lasting for about 24 s. Then, the Xiaoyudong fault was triggered by the Pengguan fault, and the bilateral rupture of the high dip angle part of the Beichuan fault started at about 6 s. South section of the Beichuan fault began to break at about 35 s, and at 43 s, 63 s, and 80 s, the rupture extended to Beichuan, Nanba, and Qingchuan areas.

scholarly journals Nonlinear inversion method based on dynamics model modification

2019 ◽  
Vol 288 ◽  
pp. 01003
Author(s):  
Faping Zhang ◽  
Kai Wu
Keyword(s):  
Dynamic Models ◽  
Error Function ◽  
Experimental Results ◽  
Inversion Method ◽  
Nonlinear Inversion ◽  
Forward Modelling ◽  
Dynamics Model ◽  
Model Modification ◽  
Simulation Results ◽  
The Cost

In the fields of modern aviation system, subgrade vehicle system and complex mechanical system, there is a problem that parameters of most dynamic models are inaccurate. This problem results in a large difference between the model results and the experimental results. In order to solve this problem, this paper build a nonlinear inversion method based on dynamics model modification (NIDM). Firstly, the error relationship was obtained by integrating the experimental data with the simulation results of the forward modelling model by the cost function and penalty function. Then, the problem of error function minimization was solved by using the parameter iteration generated by particle swarm optimization algorithm, and the corrected parameters of the forward modelling model were obtained. Finally, the method was tested by building a vehicle suspension vibration model and a pavement excitation model as test samples. The test results show that the fitting degree between the simulation results and the experimental results can be effectively improved by modifying the parameters of the dynamic model based on the NIDM method.

Generalization of traveltime inversion

Geophysics ◽  
1992 ◽  
Vol 57 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Gérard C. Herman
Keyword(s):  
Time Windows ◽  
Velocity Model ◽  
Inversion Method ◽  
Nonlinear Inversion ◽  
Error Norm ◽  
Arrival Times ◽  
Traveltime Inversion ◽  
Velocity Models ◽  
Use Of Data

A nonlinear inversion method is presented, especially suited for the determination of global velocity models. In a certain sense, it can be considered as a generalization of methods based on traveltimes of reflections, with the requirement of accurately having to determine traveltimes replaced by the (less stringent and less subjective) requirement of having to define time windows around main reflections (or composite reflections) of interest. It is based on an error norm, related to the phase of the wavefield, which is directly computed from wavefield measurements. Therefore, the cumbersome step of interpreting arrivals and measuring arrival times is avoided. The method is applied to the reconstruction of a depth‐dependent global velocity model from a set of plane‐wave responses and is compared to other methods. Despite the fact that the new error norm only makes use of data having a temporal bandwidth of a few Hz, its behavior is very similar to the behavior of the error norm used in traveltime inversion.

3-D resistivity inversion using the finite‐element method

Geophysics ◽  
1994 ◽  
Vol 59 (12) ◽  
pp. 1839-1848 ◽  
Author(s):  
Yutaka Sasaki
Keyword(s):  
Finite Element ◽  
Approximate Method ◽  
Synthetic Data ◽  
Computation Time ◽  
Inversion Method ◽  
Data Sets ◽  
Near Surface ◽  
Partial Derivatives ◽  
Homogeneous Half Space ◽  
Resistivity Inversion

With the increased availability of faster computers, it is now practical to employ numerical modeling techniques to invert resistivity data for 3-D structure. Full and approximate 3-D inversion methods using the finite‐element solution for the forward problem have been developed. Both methods use reciprocity for efficient evaluations of the partial derivatives of apparent resistivity with respect to model resistivities. In the approximate method, the partial derivatives are approximated by those for a homogeneous half‐space, and thus the computation time and memory requirement are further reduced. The methods are applied to synthetic data sets from 3-D models to illustrate their effectiveness. They give a good approximation of the actual 3-D structure after several iterations in practical situations where the effects of model inadequacy and topography exist. Comparisons of numerical examples show that the full inversion method gives a better resolution, particularly for the near‐surface features, than does the approximate method. Since the full derivatives are more sensitive to local features of resistivity variations than are the approximate derivatives, the resolution of the full method may be further improved when the finite‐element solutions are performed more accurately and more efficiently.

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