Saliency-Map Guided Salt Prediction by a Multi-Channel Convolutional Neural Network

One of the major challenges in seismic imaging is accurately delineating subsurface salt. Since a salt boundary has strong impedance compared with other sediments, we build a saliency map with intensity and orientation to create a pixel-level model for salt interpretation. In this abstract, we train a saliency-map as an additional attribute to combine with the original seismic to predict salt bodies. We also train a saliency-map to classify multiple geological facies in a multi-channel convolutional neural network with residual net architecture to help build subsurface velocity models. Two examples are shown which demonstrate that a saliency-map-plus-seismic model successfully improves the accuracy of salt prediction and reduces artifacts.

POSSIBILITIES OF OBJECT-ORIENTED MIGRATION FOR IMAGING THE PRE-JURASSIC DEPOSITS

The paper presents the results of testing several migration procedures with an emphasis on the possibility of object-oriented imaging of the pre-Jurassic deposits. Numerical examples are calculated for synthetic data obtained for a realistic seismic model of pre-Jurassic deposits, built from real data from Western Siberia.

Adjoint Seismic Tomography of the Antarctic Continent Incorporating Green's Functions from Ambient Noise Correlation

<p>The Antarctic continent with its large ice sheets provides a unique environment to investigate the response of the solid Earth to ice mass change. A key requirement of such studies is high-resolution seismic images of the crust and upper mantle, which can be used to estimate the region’s viscous structure. Likewise, these images are key to understanding the region’s geologic history and underlying geodynamic processes. Although the existing transverse isotropic seismic model ANT-20(Lloyd et al., 2020) and azimuthally anisotropic seismic model ANT-30 (Lloyd et al., in prep) have regional-scale resolution from the upper mantle to the transition zone, there is a need for higher resolution within the uppermost mantle (< 75 km) and crust of Antarctica. In this study, we use the ANT-30 model (Lloyd et al., in prep), a 3D seismic model from earthquake data, as a starting model. We seek to improve its resolution within the upper ~100 km of the Antarctic mantle by fitting three-component ambient noise correlograms computed from broadband records collected in Antarctica over the past 20 years. This includes data from recent temporary arrays such as TAMSEIS, AGAP, TAMNNET, RIS, POLENET/ANET, and UKANET. The three-component cross-correlations of station pairs are calculated and properly rotated to extract ambient noise surface waves that include both Rayleigh and Love waves, which show excellent signal-to-noise ratio between 15 to 70 seconds. The benefit of including this data is twofold: (1) it provides surface wave observations down to 15 s, as opposed to 25 s and (2) it provides shorter intercontinental paths, which were absent due to the region’s earthquake distribution. We then use the software package SPECFEM3D_GLOBE to iteratively improve the 3-D earth model, minimizing the nondimensionalized traveltime phase misfit between the observed and synthetic waveforms. The preliminary results indicate a stronger positive radial anisotropy (V<sub>SH</sub> > V<sub>SV</sub>) in the lower crust and uppermost mantle for West Antarctica and part of East Antarctica.  With more iterations, smaller-scale detail can be revealed by the new ambient noise data, resulting in a more reliable uppermost mantle and crustal structure.</p>

Shallow seismic structure beneath the continental China revealed by P-wave polarization, Rayleigh wave ellipticity and receiver function

SUMMARY We construct a high-resolution shallow 3-D seismic model in the top 10 km of the upper crust in the continental China, with constraints of P polarization, Rayleigh wave ellipticity and receiver function obtained from records of 3848 seismic stations. Our 3-D seismic model has a spatial resolution of 0.6–1.2° in the north–south seismic belt and the trans-north China orogen, and 1–2° in the rest of the continental China (except the Tarim basin and the southwest Tibet). The seismic model exhibits low velocity anomalies of deposits in major sedimentary basins and high velocity anomalies of crustal bedrocks in young orogenic belts and old tectonic blocks. The inferred sediment thickness maps display thick deposits in major sedimentary basins, some compacted sediments in the intermontane basins in young orogenic belts and little sediments in old tectonic blocks. We also discuss compaction effects of the sediments and implications of tectonic history and geological evolution of the major basins in the continental China based on the inferred seismic models. This study provides an effective mean of seismic imaging through joint inversion of various seismic constraints and establishes a framework of seismic data sharing for future studies in the seismological community in a first step of developing a China Seismological Reference Model.

Geo-seismic model for petroleum plays an assessment of the Zamzama area, Southern Indus Basin, Pakistan

Seismic as well as structural techniques were exploited to elucidate the subsurface structure of the Zamzama area that directly led to petroleum system. Zamzama gas field is located in the Kirthar Foredeep, southern Indus Basin, Pakistan. The current research is based on data scrutinized systematically through eight seismic lines (796-JH-01, 02, 03, 07, 10, GHPK-98A-32, 34 and 40) and three wells (Zamzama-02, 03 and 05) drilled in the Zamzama field. Seismic interpretation reveals that Tertiary and Cretaceous sequence is deformed by transpressive tectonics, and a reverse fault is located from 400 to 3400 ms deep on the vertical seismic section. The hanging wall moves up along the fault plane under the action of eastward directed stress as a result an extensive North–South oriented and eastward verging thrusted anticline is formed. Stratigraphically, area encompasses well-developed Mesozoic–Cenozoic sequence. The Late Cretaceous Pab Formation is well-known primary hydrocarbon reservoir capped by the shale of the Paleocene Ranikot Formation that acts as a regional seal rock. The Jurassic and Cretaceous shales of the Sember and Goru formations are substantiated as main source rocks. The execution and portrayal of seismic and subsurface geological data provide the clues that area contains appropriate petroleum play potential. Present study suggests a worthwhile regional geo-seismic model that might be significant for future exploration in the Kirther Foredeep and adjacent areas.