Tailored acquisition and processing providing an enhanced subsurface image of the basin architecture, Exmouth Sub-basin, North West Shelf, Australia

2019 ◽  
Vol 59 (2) ◽  
pp. 886
Author(s):  
Alexander Karvelas ◽  
Bee Jik Lim ◽  
Lianping Zhang ◽  
Haryo Trihutomo ◽  
Oliver Schenk ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Model Building ◽  
Waveform Inversion ◽  
Hydrocarbon Exploration ◽  
Surface Velocity ◽  
Seismic Survey ◽  
Image Point ◽  
Surface Model ◽  
Near Surface ◽  
North West

Hydrocarbon exploration has resulted in the discovery of a variety of oil and gas accumulations mainly in Upper Jurassic and Lower Cretaceous intervals. However, the distribution of the different petroleum system elements including Jurassic and Triassic intervals is poorly determined, but required for improved understanding of the complex charge history, as indicated by the variety of hydrocarbon types encountered in the basin. The new WesternGeco multiclient 3D seismic survey extends to the edges of the basin to give a comprehensive picture. Raw hydrophone data were delivered from the vessel as acquisition progressed to begin the near-surface model building. The model building consisted of two major stages: first, using full waveform inversion (FWI) to derive the near-surface velocity field; and, second, common image point (CIP) tomography to update the deeper section beyond the FWI illumination zone. As illustrated herein, various stages of processing and imaging provided a cleaner and crisper dataset across the record length, allowing (1) detailed picking of the events within the entire Mesozoic (Cretaceous–Triassic) section allowing key events to be interpreted and correlated across the area and (2) accurate investigation of the complexity of different aged fault networks and their relationships across the full Exmouth Sub-basin for the first time. In summary, this survey provides a detailed insight into the deeper basin architecture of the Exmouth Sub-basin. The seamless volume imaged to depth allows accurate mapping which is critical to unravel the complex evolutionary history in a basin with proven and significant remaining hydrocarbon potential.

Full waveform inversion: early start of model building process to resolve the complex near surface model in the Exmouth sub-basin, North West Shelf Australia

2018 ◽  
Vol 58 (2) ◽  
pp. 884
Author(s):  
Lianping Zhang ◽  
Haryo Trihutomo ◽  
Yuelian Gong ◽  
Bee Jik Lim ◽  
Alexander Karvelas
Keyword(s):  
Model Building ◽  
Waveform Inversion ◽  
Velocity Model ◽  
Surface Velocity ◽  
Image Point ◽  
Surface Model ◽  
Full Waveform Inversion ◽  
Near Surface ◽  
North West ◽  
Full Waveform

The Schlumberger Multiclient Exmouth 3D survey was acquired over the Exmouth sub-basin, North West Shelf Australia and covers 12 600 km2. One of the primary objectives of this survey was to produce a wide coverage of high quality imaging with advanced processing technology within an agreed turnaround time. The complexity of the overburden was one of the imaging challenges that impacted the structuration and image quality at the reservoir level. Unlike traditional full-waveform inversion (FWI) workflow, here, FWI was introduced early in the workflow in parallel with acquisition and preprocessing to produce a reliable near surface velocity model from a smooth starting model. FWI derived an accurate and detailed near surface model, which subsequently benefitted the common image point (CIP) tomography model updates through to the deeper intervals. The objective was to complete the FWI model update for the overburden concurrently with the demultiple stages hence reflection time CIP tomography could start with a reasonably good velocity model upon completion of the demultiple process.

Model–parameterization scaling for improving accuracy of seismic tomography in reconstructing near–surface velocity model

2020 ◽  
Author(s):  
Gleb S. Chernyshov ◽  
◽  
Anton A. Duchkov ◽  
Aleksander A. Nikitin ◽  
Ivan Yu. Kulakov ◽  
...  
Keyword(s):  
Model Building ◽  
Regularization Parameter ◽  
Velocity Model ◽  
Surface Velocity ◽  
Surface Model ◽  
Tomographic Inversion ◽  
Near Surface ◽  
Model Parameterization ◽  
Regularization Parameters ◽  
Improving Accuracy

The problem of tomographic inversion is non–unique and requires regularization to solve it in a stable manner. It is highly non–trivial to choose between various regularization approaches or tune the regularization parameters themselves. We study the influence of one particular regularization parameter on the resolution and accuracy the tomographic inversion for the near–surface model building. We propose another regularization parameter, which allows to increase the accuracy of model building.

Near-surface modeling challenges highlighted in recent workshop

2020 ◽  
Vol 39 (5) ◽  
pp. 354-356
Author(s):  
Abdulaziz Saad ◽  
Moosa Al-Jahdhami
Keyword(s):  
Guided Waves ◽  
Joint Inversion ◽  
Waveform Inversion ◽  
Surface Modeling ◽  
Hydrocarbon Exploration ◽  
Surface Model ◽  
Near Surface ◽  
Velocity Inversion ◽  
Geophysical Imaging ◽  
Near Surface Geophysics

Despite technological and computational advances in geophysical imaging, near-surface geophysics continues to pose significant challenges in modeling and imaging the subsurface. Geoscientists from around the world attended the first and second editions of the SEG/DGS Near-surface Modeling and Imaging Workshop in 2014 and 2016 to address these challenges. A range of near-surface disciplines were represented from academia and industry, covering aspects of engineering and hydrocarbon exploration. The previous workshops explored emerging and underdeveloped techniques, including deep learning (machine learning), nonseismic methods, full-waveform inversion (FWI), and joint inversion. The necessity to further understand guided waves, anisotropy, velocity inversion, and the creation of an inclusive near-surface model was identified. The previous editions led to a greater understanding of the importance of knowledge sharing among various disciplines in modeling and imaging of the near surface.

Unlocking ultra-high-density seismic for CCUS applications by combining nimble nodes and agile source technologies

2022 ◽  
Vol 41 (1) ◽  
pp. 27-33
Author(s):  
Amine Ourabah ◽  
Allan Chatenay
Keyword(s):  
Carbon Capture ◽  
Oil And Gas ◽  
Test Site ◽  
High Density ◽  
Seismic Survey ◽  
Surface Model ◽  
Near Surface ◽  
Seismic Surveys ◽  
Time Migration ◽  
Trace Density

In the quest for denser, nimbler, and lower-cost seismic surveys, the industry is seeing a revolution in the miniaturization of seismic equipment, with autonomous nodes approaching the size of a geophone and sources becoming portable by crews on foot. This has created a paradigm shift in the way seismic is acquired in difficult terrains, making zero-environmental-footprint surveys a reality while reducing cost and health, safety, and environmental risk. The simplification of survey operation and the new entry price of seismic surveys unlocked by these technologies are already benefiting industries beyond oil and gas exploration. High trace density seismic has become accessible to industries playing a key role in the net-zero era, such as geothermal and carbon capture, utilization, and storage (CCUS), to which a good understanding of the subsurface geology is crucial to their success. We describe these benefits as observed during an ultra-high-density seismic survey acquired in June 2020 through a partnership between STRYDE, Explor, and Carbon Management Canada over the Containment and Monitoring Institute site. The smallest and lightest source and receiver equipment in the industry were used to achieve a trace density of 257 million traces/km2 over this test site dedicated to CCUS studies. We discuss the operational efficiency of the seismic acquisition, innovative techniques for data transfer and surveying, and preliminary results of the seismic data processing with a focus on the near-surface model and fast-track time migration.

High-resolution Radon preconditioning for full-waveform inversion of land seismic data

2017 ◽  
Vol 5 (4) ◽  
pp. SR23-SR33 ◽  
Author(s):  
Xin Cheng ◽  
Kun Jiao ◽  
Dong Sun ◽  
Zhen Xu ◽  
Denes Vigh ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Velocity Fields ◽  
Surface Velocity ◽  
Surface Model ◽  
Full Waveform Inversion ◽  
Near Surface ◽  
Full Waveform

Over the past decade, acoustic full-waveform inversion (FWI) has become one of the standard methods in the industry to construct high-resolution velocity fields from the seismic data acquired. While most of the successful applications are for marine acquisition data with rich low-frequency diving or postcritical waves at large offsets, the application of acoustic FWI on land data remains a challenging topic. Land acoustic FWI application faces many severe difficulties, such as the presence of strong elastic effects, large near-surface velocity contrast, and heterogeneous, topography variations, etc. In addition, it is well-known that low-frequency transmitted seismic energy is crucial for the success of FWI to overcome sensitivity to starting velocity fields; unfortunately, those are the parts of the data that suffer the most from a low signal-to-noise ratio (S/N) in land acquisition. We have developed an acoustic FWI application on a land data set from North Kuwait, and demonstrated our solutions to mitigate some of the challenges posed by land data. More specifically, we have developed a semblance-based high-resolution Radon (HR-Radon) inversion approach to enhance the S/N of the low-frequency part of the FWI input data and to ultimately improve the convergence of the land FWI workflow. To mitigate the impact of elastic effects, we included only the diving and postcritical early arrivals in the waveform inversion. Our results show that, with the aid of HR-Radon preconditioning and a carefully designed workflow, acoustic FWI has the ability to derive a reliable high-resolution near-surface model that could not be otherwise recovered through traditional tomographic methods.

Estimating smectite content from seismic data

2019 ◽  
Vol 59 (2) ◽  
pp. 851
Author(s):  
Roman Beloborodov ◽  
Marina Pervukhina ◽  
Valeriya Shulakova ◽  
Dimitri Chagalov ◽  
Matthew Josh ◽  
...  
Keyword(s):  
Seismic Data ◽  
Oil And Gas ◽  
Clay Mineralogy ◽  
Mineralogical Composition ◽  
Hydrocarbon Exploration ◽  
Seismic Survey ◽  
Maximum Deviation ◽  
North West ◽  
Northern Carnarvon Basin ◽  
Carnarvon Basin

Predicting the mineralogical composition of shales is crucial for drilling operations related to hydrocarbon exploration/production as well as for the assessment of their sealing capacity as hydrocarbon or CO2 barriers. For example, hydrocarbon exploration in the Northern Carnarvon Basin, North-West Shelf, Australia is hindered by the presence of a thick (up to 1 km) smectite-rich shale seal that spreads regionally. Complex structures of the channelised oil and gas fields in the area make it necessary to drill deviated wells through that seal. The maximum deviation angle at which successful drilling is possible depends strongly on the clay mineralogy and, in particular, on the smectite content in the shale. Here, we introduce a novel workflow combining seismic data, well logs and laboratory measurements to infer shale composition at the reservoir scale. It is applied to the Duyfken 3D seismic survey in the central part of the Northern Carnarvon Basin. Interpretation results are verified against the laboratory X-ray diffraction measurements from the test well that was not used for the interpretation. The results match the test data well within the determined uncertainty bounds.

Robust refraction statics solution and near-surface velocity model building using feedback from reflection data

Geophysics ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. U63-U77
Author(s):  
Bernard K. Law ◽  
Daniel Trad
Keyword(s):  
Model Building ◽  
Waveform Inversion ◽  
Velocity Model ◽  
Surface Velocity ◽  
Near Surface ◽  
Arrival Times ◽  
Reflection Data ◽  
Velocity Model Building ◽  
First Arrival ◽  
Refraction Data

An accurate near-surface velocity model is critical for weathering statics correction and initial model building for depth migration and full-waveform inversion. However, near-surface models from refraction inversion often suffer from errors in refraction data, insufficient sampling, and over-simplified assumptions used in refraction algorithms. Errors in refraction data can be caused by picking errors resulting from surface noise, attenuation, and dispersion of the first-arrival energy with offset. These errors are partially compensated later in the data flow by reflection residual statics. Therefore, surface-consistent residual statics contain information that can be used to improve the near-surface velocity model. We have developed a new dataflow to automatically include median and long-wavelength components of surface-consistent reflection residual statics. This technique can work with any model-based refraction solution, including grid-based tomography methods and layer-based methods. We modify the cost function of the refraction inversion by adding model and data weights computed from the smoothed surface-consistent residual statics. By using an iterative inversion, these weights allow us to update the near-surface velocity model and to reject first-arrival picks that do not fit the updated model. In this nonlinear optimization workflow, the refraction model is derived from maximizing the coherence of the reflection energy and minimizing the misfit between model arrival times and the recorded first-arrival times. This approach can alleviate inherent limitations in shallow refraction data by using coherent reflection data.

scholarly journals Selected aspects of modern seismic imaging and near-surface velocity model building in the area of Carpathian fold and thrust belt

2021 ◽  
Vol 47 (2) ◽  
Author(s):  
Andrzej Michał Dalętka
Keyword(s):  
Model Building ◽  
Geophysical Methods ◽  
Velocity Model ◽  
Hydrocarbon Exploration ◽  
Surface Velocity ◽  
Structural Representation ◽  
Near Surface ◽  
Velocity Model Building ◽  
Orogenic Wedge ◽  
Refraction Tomography

Despite the increasing technological level of the reflection seismic method, the imaging of fold and thrust belts remains a demanding task, and usually leaves some questions regarding the dips, the shape of the subthrust structures or the most correct approach to velocity model building. There is no straightforward method that can provide structural representation of the near-surface geological boundaries and their velocities. The in-terpretation of refracted waves frequently remains the only available technique that may be used for this purpose, although one must be aware of its limitations which appear in the complex geological settings. In the presented study, the analysis of velocity values obtained in the shallow part of Carpathian orogenic wedge by means of various geophysical methods was carried out. It revealed the lack of consistency between the results of 3D refraction tomography and both the sonic log and uphole velocities. For that reason, instead of the indus-try-standard utilization of tomography, a novel, geologically-consistent method of velocity model building is pro-posed. In the near-surface part, the uphole velocities are assigned to the formations, documented by the surface geologic map. Interpreted time-domain horizons, supplemented by main thrusts, are used to make the velocity field fully-compatible with the litho-stratigraphic units of the Carpathians. The author demonstrates a retrospective overview of seismic data imaging in the area of the Polish Carpathian orogenic wedge and discusses the most recent global innovations in seismic methodology which are the key to successful hydrocarbon exploration in fold and thrust regions.

Integrated turning-ray and reflection tomography for velocity model building in foothill areas

2018 ◽  
Vol 6 (4) ◽  
pp. SM63-SM70 ◽  
Author(s):  
Tian Jun ◽  
Peng Gengxin ◽  
Junru Jiao ◽  
Grace (Yan) Yan ◽  
Xianhuai Zhu
Keyword(s):  
Model Building ◽  
Synthetic Data ◽  
Velocity Model ◽  
Surface Velocity ◽  
Seismic Exploration ◽  
Surface Model ◽  
Near Surface ◽  
Velocity Model Building ◽  
Tomographic Method ◽  
Reflection Tomography

A special challenge for land seismic exploration is estimating velocities, in part due to complex near-surface structures, and in some instances because of rugose topography over foothills. We have developed an integrated turning-ray and reflection-tomographic method to face this challenge. First, turning-ray tomography is performed to derive a near-surface velocity-depth model. Then, we combine the near-surface model with the initial-subsurface model. Taking the combined model as starting model, we go through a reflection tomographic process to build the model for imaging. During reflection tomography, the near-surface model and subsurface models are jointly updated. Our method has been successfully applied to a 2D complex synthetic data example and a 3D field data example. The results demonstrate that our method derives a very decent model even when there is no reflection information available in a few hundred meters underneath the surface. Joint tomography can lead to geologic plausible models and produce subsurface images with high fidelity.

Sign in / Sign up

Export Citation Format

Share Document