scholarly journals 2D High-Resolution Crosswell Seismic Traveltime Tomography

2020 ◽  
Vol 25 (1) ◽  
pp. 47-53
Author(s):  
Chuan Li ◽  
JianXin Liu ◽  
Jianping Liao ◽  
Andrew Hursthouse
Keyword(s):  
High Resolution ◽  
Eastern China ◽  
Velocity Model ◽  
Well Logging ◽  
Oil Field ◽  
Traveltime Tomography ◽  
Reference Velocity ◽  
Velocity Information ◽  
High Resolution Reconstruction

This paper presents a method for combining the hybrid eikonal solver and the prior velocity information to obtain high-resolution crosswell imaging. The hybrid eikonal solver in this technique can ensure rapid and reliable forward modeling of traveltime field in an unsmoothed velocity model. We also utilize the sonic well logging curve to properly develop an initial reference velocity model, and use the sonic well logging data as the prior information for the inversion part, which can restrict the problem of non-uniqueness. The results of the numerical experiment of traveltime in multi-layer media showed that the hybrid eikonal solver was more accurate than the finite difference method. The case study of an oil field in eastern China demonstrated that our method can derive a high-resolution reconstruction of the subsurface structure by inverting the primary traveltime datasets. These results suggest that even though the eikonal equation is a high frequency approximation to the wavefield, the hybrid eikonal solver can provide an accurate traveltime field in the forward modelling step of seismic crosswell tomography, which is critical to ensure high-resolution invert imaging in a highly heterogeneous environment.

scholarly journals Application of Frequency-Dependent Traveltime Tomography to 2D Crosswell Seismic Field Data

2017 ◽  
Vol 22 (4) ◽  
pp. 421-426 ◽  
Author(s):  
Jianping Liao ◽  
Zhenwei Guo ◽  
Hexiu Liu ◽  
Shixin Dai ◽  
Yanlin Zhao ◽  
...  
Keyword(s):  
High Resolution ◽  
Field Data ◽  
Seismic Waves ◽  
Velocity Model ◽  
Oil Field ◽  
Frequency Dependent ◽  
Traveltime Tomography ◽  
First Arrival ◽  
Forward And Inverse Modeling ◽  
High Resolution Reconstruction

We applied Zelt's new frequency-dependent traveltime tomography (FDTT) method to 2D crosswell seismic field data from an eastern oil field in China. The FDTT uses the frequency content in the seismic waves in both the forward and inverse modeling steps. Although FDTT only uses a 300 Hz frequency to invert the dataset, the degree of matching between the inverted layers from FDTT and that of a sonic well logging curve is high, which shows that FDTT provides a high resolution reconstruction of subsurface structure through the simple use of the first-arrival traveltime data. The case study demonstrates that the FDTT algorithm is practical and can stand up to the complexities of a real 2D crosswell dataset. Additionally, we show that the FDTT method can create a high resolution long wavelength velocity model.

The value of VSP data through early phases of field appraisal and development: A modeling and acquisition case study in the Gulf of Mexico

2019 ◽  
Vol 38 (11) ◽  
pp. 850-857 ◽  
Author(s):  
Peter Lanzarone ◽  
Elizabeth L'Heureux ◽  
Qingsong Li
Keyword(s):  
Gulf Of Mexico ◽  
Reservoir Characterization ◽  
Velocity Model ◽  
Complex Salt ◽  
Oil Field ◽  
Ultrahigh Pressure ◽  
Vsp Data ◽  
The Impact ◽  
Early Phases

The Gulf of Mexico is a rich hydrocarbon province that contains a diversity of petroleum systems play types. Often, identifying drilling targets can be challenging when solely using surface seismic data, particularly in areas with complex salt structures in the overburden. In this paper, we present a vertical seismic profile (VSP) modeling and acquisition case study for an oil field located in a subsalt, deepwater, ultrahigh-pressure high-temperature environment. Our objective was to model the subsurface to guide the acquisition of VSP data during the early phases of exploration and appraisal drilling. In the first exploration well, a salt-proximity VSP designed in a walkaway configuration was carried out to help better define the geometry of a salt overhang and verify anisotropy parameters, helping to reduce a critical uncertainty for imaging the subsalt structure across a large segment within our field area. In the first appraisal well, a zero-offset VSP was collected to establish a direct well tie and further calibrate our velocity model. In the second appraisal well, we utilized walkaway VSP data to form a high-frequency stratigraphic image between the two appraisal wellbores. These data were used to generate an enhanced image of the reservoir section that revealed subtle stratigraphic boundaries, another key subsurface uncertainty. Finally, we modeled both ambitious and conservative 3D VSP acquisition designs to understand the imaging area achieved through a 3D acquisition and undertook an assessment to understand the impact of PP and PS imaging for reservoir characterization. We conclude that VSP data are valuable tools in the early phases of field appraisal and development, and we demonstrate the business value of VSPs to optimize development drilling locations in our study area.

Reference velocity model estimation from prestack waveforms: Coherency optimization by simulated annealing

Geophysics ◽  
1989 ◽  
Vol 54 (8) ◽  
pp. 984-990 ◽  
Author(s):  
Evgeny Landa ◽  
Wafik Beydoun ◽  
Albert Tarantola
Keyword(s):  
Monte Carlo ◽  
Simulated Annealing ◽  
Velocity Model ◽  
Monte Carlo Step ◽  
Lateral Velocity ◽  
Seismic Waveforms ◽  
Reference Velocity ◽  
Velocity Information ◽  
Zero Offset ◽  
Annealing Method

Coherency inversion, which consists of maximizing a semblance function calculated from unstacked seismic waveforms, has the potential of estimating reliable velocity information without requiring traveltime picking on unstacked data. In this work, coherency inversion is based on the assumption that reflectors’ zero‐offset times are known and that the velocity in each layer may vary laterally. The method uses a type of Monte Carlo technique termed the generalized simulated annealing method for updating the velocity field. At each Monte Carlo step, time‐to‐depth conversion is performed. Although this procedure is slow at convergence to the global minimum, it is robust and does not depend on the initial model or topography of the objective function. Applications to both synthetic and field data demonstrate the efficiency of coherency inversion for estimating both lateral velocity variations and interface depth positions.

High Resolution Imaging of the South Hikurangi Subduction Zone, New Zealand, Using 2‐D Full‐Waveform Inversion

2020 ◽  
Author(s):  
Adnan Djeffal ◽  
Ingo Pecher ◽  
Satish Singh ◽  
Jari Kaipio
Keyword(s):  
New Zealand ◽  
High Resolution ◽  
Seismic Data ◽  
Waveform Inversion ◽  
Velocity Model ◽  
Seismic Profile ◽  
Full Waveform Inversion ◽  
Traveltime Tomography ◽  
Full Waveform ◽  
Velocity Images

<p>Large quantities of fluids are predicted to be expelled from compacting sediments on subduction margins. Fluid expulsion is thought to be focussed, but its exact locations are usually constrained on very small scales and rarely can be resolved using velocity images obtained from traditional velocity analysis and ray-based tomography because of their resolution and accuracy limitation. However, with recent advancement in computing power, the full waveform inversion (FWI) is a powerful alternative to those traditional approaches as it uses phase and amplitude information contained in seismic data to yield a high-resolution velocity model of the subsurface.</p><p>Here, we applied elastic FWI along an 85 Km long 2D multichannel seismic profile on the southern Hikurangi margin, New Zealand. Our processing sequence includes: (1) downward continuation, (2) 2D traveltime tomography, and (3) full waveform inversion of wide-angle seismic data. We will present the final high-resolution velocity model and our interpretation of the fluid flow regimes associated with both the deforming overriding plate and the subducting plate.</p>

Imaging high-resolution seismic velocity from walkaway vertical seismic profile data in a carbonate reservoir using acoustic waveform tomography

Geophysics ◽  
2018 ◽  
Vol 83 (3) ◽  
pp. B77-B85 ◽  
Author(s):  
Eric M. Takam Takougang ◽  
Youcef Bouzidi
Keyword(s):  
High Resolution ◽  
United Arab Emirates ◽  
Seismic Velocity ◽  
Velocity Model ◽  
Seismic Profile ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Vertical Seismic Profile ◽  
Final Velocity ◽  
Waveform Tomography

High-resolution seismic velocity was obtained using acoustic full-waveform tomography of walkaway vertical seismic profile (VSP) data from an oil field dominated by carbonate rocks, offshore Abu Dhabi in the United Arab Emirates. The data were collected in a deviated borehole with receivers located from 521 to 2742 m depth. The inversion was performed in the frequency domain. The success of the inversion was determined by three important factors: the starting model, the preconditioning of the input data, and the inversion strategy, which included an appropriate selection of a damping term [Formula: see text] in the Laplace–Fourier transformation. The inversion was performed between the frequencies of 4 and 50 Hz, and a logarithmic data residual was used. The extracted 1D velocity profiles from the final high-resolution velocity model correlate well with the sonic log, and estimated vertical incidence VSP velocities. The predicted data obtained by the final velocity model indicate a generally good fit with the field data, thus confirming the success of the inversion. A reverse time migrated section derived by the final velocity model provides additional structural details. The velocity model indicates anomalous zones of low-velocity values that correlate with known locations of hydrocarbon reservoirs.

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