Seismic fault attribute estimation using a local fault model

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. O73-O80 ◽  
Author(s):  
Yihuai Lou ◽  
Bo Zhang ◽  
Ruiqi Wang ◽  
Tengfei Lin ◽  
Danping Cao
Keyword(s):  
Seismic Data ◽  
Fault Plane ◽  
3D Seismic ◽  
Seismic Amplitude ◽  
Seismic Fault ◽  
Analysis Window ◽  
Full Analysis ◽  
Fault Interpretation ◽  
Analysis Point ◽  
Staircase Artifacts

Faults in the subsurface can be an avenue of, or a barrier to, hydrocarbon flow and pressure communication. Manual interpretation of discontinuities on 3D seismic amplitude volume is the most common way to define faults within a reservoir. Unfortunately, 3D seismic fault interpretation can be a time-consuming and tedious task. Seismic attributes such as coherence help define faults, but suffer from “staircase” artifacts and nonfault-related stratigraphic discontinuities. We assume that each sample of the seismic data is located at a potential fault plane. The hypothesized fault divides the seismic data centered at the analysis sample into two subwindows. We then compute the coherence for the two subwindows and full analysis window. We repeat the process by rotating the hypothesized fault plane along a set of user-defined discrete fault dip and azimuth. We obtain almost the same coherence values for the subwindows and the full window if the analysis point is not located at a fault plane. The “best” fault plane results in maximum coherence for the subwindows and minimum coherence for the full window if the analysis point is located at a fault plane. To improve the continuity of the fault attributes, we finally smooth the fault probability attribute along the estimated fault plane. We illustrate the effectiveness of our workflow by applying it to a synthetic and two real seismic data. The results indicate that our workflow successfully produces a continuous fault attribute without staircase artifacts and stratigraphic discontinuities.

Improving seismic fault detection by super-attribute-based classification

2019 ◽  
Vol 7 (3) ◽  
pp. SE251-SE267 ◽  
Author(s):  
Haibin Di ◽  
Mohammod Amir Shafiq ◽  
Zhen Wang ◽  
Ghassan AlRegib
Keyword(s):  
Fault Detection ◽  
Seismic Data ◽  
Support Vector ◽  
3D Seismic ◽  
Subsurface Structure ◽  
Computationally Efficient ◽  
Seismic Fault ◽  
Conventional Methods ◽  
Fault Interpretation ◽  
3D Seismic Data

Fault interpretation is one of the routine processes used for subsurface structure mapping and reservoir characterization from 3D seismic data. Various techniques have been developed for computer-aided fault imaging in the past few decades; for example, the conventional methods of edge detection, curvature analysis, red-green-blue rendering, and the popular machine-learning methods such as the support vector machine (SVM), the multilayer perceptron (MLP), and the convolutional neural network (CNN). However, most of the conventional methods are performed at the sample level with the local reflection pattern ignored and are correspondingly sensitive to the coherent noises/processing artifacts present in seismic signals. The CNN has proven its efficiency in utilizing such local seismic patterns to assist seismic fault interpretation, but it is quite computationally intensive and often demands higher hardware configuration (e.g., graphics processing unit). We have developed an innovative scheme for improving seismic fault detection by integrating the computationally efficient SVM/MLP classification algorithms with local seismic attribute patterns, here denoted as the super-attribute-based classification. Its added values are verified through applications to the 3D seismic data set over the Great South Basin (GSB) in New Zealand, where the subsurface structure is dominated by polygonal faults. A good match is observed between the original seismic images and the detected lineaments, and the generated fault volume is tested usable to the existing advanced fault interpretation tools/modules, such as seeded picking and automatic extraction. It is concluded that the improved performance of our scheme results from its two components. First, the SVM/MLP classifier is computationally efficient in parsing as many seismic attributes as specified by interpreters and maximizing the contributions from each attribute, which helps minimize the negative effects from using a less useful or “wrong” attribute. Second, the use of super attributes incorporates local seismic patterns into training a fault classifier, which helps exclude the random noises and/or artifacts of distinct reflection patterns.

Amplitude and frequency anomalies in regional 3D seismic data surrounding the Mallik 5L-38 research site, Mackenzie Delta, Northwest Territories, Canada

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. B183-B191 ◽  
Author(s):  
M. Riedel ◽  
G. Bellefleur ◽  
S. R. Dallimore ◽  
A. Taylor ◽  
J. F. Wright
Keyword(s):  
Northwest Territories ◽  
Gas Hydrate ◽  
Seismic Data ◽  
Ratio Method ◽  
Unfrozen Water ◽  
3D Seismic ◽  
Mackenzie Delta ◽  
Data Set ◽  
Seismic Amplitude ◽  
3D Seismic Data

Amplitude and frequency anomalies associated with lakes and drainage systems were observed in a 3D seismic data set acquired in the Mallik area, Mackenzie Delta, Northwest Territories, Canada. The site is characterized by large gas hydrate deposits inferred from well-log analyses and coring. Regional interpretation of the gas hydrate occurrences is mainly based on seismic amplitude anomalies, such as brightening or blanking of seismic energy. Thus, the scope of this research is to understand the nature of the amplitude behavior in the seismic data. We have therefore analyzed the 3D seismic data to define areas with amplitude reduction due to contamination from lakes and channels and to distinguish them from areas where amplitude blanking may be a geologic signal. We have used the spectral ratio method to define attenuation (Q) over different areas in the 3D volume and subsequently applied Q-compensation to attenuate lateral variations ofdispersive absorption. Underneath larger lakes, seismic amplitude is reduced and the frequency content is reduced to [Formula: see text], which is half the original bandwidth. Traces with source-receiver pairs located inside of lakes show an attenuation factor Q of [Formula: see text], approximately half of that obtained for source-receiver pairs situated on deep, continuous permafrost outside of lakes. Deeper reflections occasionally identified underneath lakes show low-velocity-related pull-down. The vertical extent of the washout zones is enhanced by acquisition with limited offsets and from processing parameters such as harsh mute functions to reduce noise from surface waves. The strong attenuation and seismic pull-down may indicate the presence of unfrozen water in deeper lakes and unfrozen pore water within the sediments underlying the lakes. Thus, the blanking underneath lakes is not necessarily related to gas migration or other in situ changes in physical properties potentially associated with the presence of gas hydrate.

Imposing interpretational constraints on a seismic interpretation CNN

Geophysics ◽  
2021 ◽  
pp. 1-36
Author(s):  
Haibin Di ◽  
Cen Li ◽  
Stewart Smith ◽  
Zhun Li ◽  
Aria Abubakar
Keyword(s):  
Seismic Data ◽  
Recent Progress ◽  
Facies Analysis ◽  
Three Dimensional ◽  
Seismic Interpretation ◽  
3D Seismic ◽  
Geologic Time ◽  
Seismic Amplitude ◽  
Subsurface Geology ◽  
3D Seismic Data

With the expanding size of three-dimensional (3D) seismic data, manual seismic interpretation becomes time consuming and labor intensive. For automating this process, the recent progress in machine learning, particularly the convolutional neural networks (CNNs), has been introduced into the seismic community and successfully implemented for interpreting seismic structural and stratigraphic features. In principle, such automation aims at mimicking the intelligence of experienced seismic interpreters to annotate subsurface geology both accurately and efficiently. However, most of the implementations and applications are relatively simple in their CNN architectures, which primary rely on the seismic amplitude but undesirably fail to fully use the pre-known geologic knowledge and/or solid interpretational rules of an experienced interpreter who works on the same task. A general applicable framework is proposed for integrating a seismic interpretation CNN with such commonly-used knowledge and rules as constraints. Three example use cases, including relative geologic time-guided facies analysis, layer-customized fault detection, and fault-oriented stratigraphy mapping, are provided for both illustrating how one or more constraints can be technically imposed and demonstrating what added values such a constrained CNN can bring. It is concluded that the imposition of interpretational constraints is capable of improving CNN-assisted seismic interpretation and better assisting the tasks of subsurface mapping and modeling.

Fault Enhancement Method of Seismic Data

2012 ◽  
Vol 518-523 ◽  
pp. 5640-5643
Author(s):  
Lei Feng ◽  
Guang Ming Li
Keyword(s):  
Image Processing ◽  
Data Acquisition ◽  
Seismic Data ◽  
Geological Structure ◽  
Seismic Fault ◽  
Important Impact ◽  
Oil Exploitation ◽  
Enhancement Method ◽  
Orientation Information ◽  
Fault Interpretation

With the deepening of the degree of oil exploitation, investigation of geological structure is particularly important, especially those faults that have an important impact on the exploration and development of oil. However, seismic data is affected by various kinds of factors in the progress of data acquisition, which reduces SNR and interfere with the accuracy of geological structure interpretation. This paper based on image processing provides fault enhancement medthod. It can reduce random factors impact and depicte fault more clearly. This method combine anisotropy and orientation information of image, then use generalized Kuwahara filter to enhance fault. This technique has a most important value in seismic fault interpretation.

Accurate seismic dip and azimuth estimation using semblance dip guided structure tensor analysis

Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. O103-O112 ◽  
Author(s):  
Yihuai Lou ◽  
Bo Zhang ◽  
Tengfei Lin ◽  
Naihao Liu ◽  
Hao Wu ◽  
...  
Keyword(s):  
Seismic Data ◽  
Structure Tensor ◽  
Estimation Methods ◽  
Estimation Accuracy ◽  
Scanning Method ◽  
The North ◽  
Analysis Window ◽  
The North Sea ◽  
Seismic Reflectors ◽  
Analysis Point

Seismic volumetric dip and azimuth are widely used in assisting seismic interpretation to depict geologic structures such as chaotic slumps, fans, faults, and unconformities. Current popular dip and azimuth estimation methods include the semblance-based multiple window scanning (MWS) method and gradient structure tensor (GST) analysis. However, the dip estimation accuracy using the semblance scanning method is affected by the dip of seismic reflectors. The dip estimation accuracy using the GST analysis is affected by the analysis window centered at the analysis point. We have developed a new algorithm to overcome the disadvantages of dip estimation using MWS and GST analysis by combining and improving the two methods. The algorithm first obtains an estimated “rough” dip and azimuth for reflectors using the semblance scanning method. Then, the algorithm defines a window that is “roughly” parallel to the local reflectors using the estimated rough dip and azimuth. The algorithm next estimates the dip and azimuth of the reflectors within the analysis window using GST analysis. To improve the robustness of GST analysis to noise, we used analytic seismic traces to compute the GST matrix. The algorithm finally uses the Kuwahara window strategy to determine the dip and azimuth of local reflectors. To illustrate the superiority of this algorithm, we applied it to the F3 block poststack seismic data acquired in the North Sea, Netherlands. The comparison indicates that the seismic volumetric dips estimated using our method more accurately follow the local seismic reflectors than the dips computed using GST analysis and the semblance-based MWS method.

Most Extreme Curvature and its Application to Seismic Structural Interpretation

2014 ◽  
Vol 522-524 ◽  
pp. 1266-1269
Author(s):  
Zhi Hong Zheng ◽  
Jie Qing Tan ◽  
Kang Liu
Keyword(s):  
Fault Detection ◽  
Seismic Data ◽  
Negative Curvature ◽  
Fault Plane ◽  
Positive Curvature ◽  
Hydrocarbon Exploration ◽  
3D Seismic ◽  
Structural Interpretation ◽  
Structural Attribute ◽  
3D Seismic Data

Curvature, as a newly developing structural attribute, closely related to the bending of geologic body and received extensive attention of the researchers in recent years. Most positive curvature and most negative curvature in particular are widely used in fault detection and fracture prediction. In this paper, most extreme curvature was introduced into structural interpretation. Compared with the conventional curvature attributes, the advantage of most extreme curvature in fault detection was highlighted in this study. It not only clearly shown the property of fault, but also precisely indicated the location of fault plane and its variation along the strike by the dramatic change in curvature values. These findings contribute to better structural interpretation of 3D seismic data and are of great significance to hydrocarbon exploration.

FAULT ARCHITECTURE ANDTHE MECHANICS OF FAULT REACTIVATION INTHE NANCARTROUGH/LAMIN ARIA AREA OF THE TIMOR SEA, NORTHERN AUSTRALIA

2000 ◽  
Vol 40 (1) ◽  
pp. 174 ◽  
Author(s):  
M.J. de Ruig M. Trupp ◽  
D.J. Bishop ◽  
D. Kuek ◽  
D.A. Castillo
Keyword(s):  
Late Miocene ◽  
Seismic Data ◽  
Fault Plane ◽  
Fault Reactivation ◽  
3D Seismic ◽  
Oblique Collision ◽  
Late Tertiary ◽  
Timor Sea ◽  
Fault Architecture ◽  
3D Seismic Data

Fault-bounded Jurassic structures of the Timor Sea have in recent years been the focus of intensive oil exploration. A number of significant oil discoveries have highlighted the exploration potential of this area (e.g. Laminaria, Corallina, Buffalo, Elang, Kakatua), but the majority of tested structures are either underfilled or show evidence of a residual oil column, resulting from trap failure of previously hydrocarbon-bearing structures. Recent well results confirm that trap integrity remains the principal exploration risk in the Timor Sea.Fault reactivation of Jurassic hydrocarbon traps is related to late Miocene-Pliocene oblique collision between the Australian plate and the SE Asian plate complex, which caused widespread transtensional faulting. The sealing potential of fault-bounded traps is, to a large degree, controlled by the orientation of the fault plane relative to the late Miocene-Recent stress field. However, the location of potential hydrocarbon leakage pathways remains difficult to define due to the complex fault architecture and a limited understanding of the interaction between Jurassic faults and Late Tertiary tectonism.During the past few years, a wealth of new exploration wells and 3D seismic data has become available from the Laminaria High/Nancar Trough area. The use of 3D visualisation tools, seismic coherency filtering and other seismic techniques has greatly enhanced our understanding of the fault architecture of this area of the Timor Sea.The structural architecture of the Nancar Trough/ Laminaria High is made up of several different structural intervals that are stratigraphically separated and partially decoupled along thick claystone intervals. Fault blocks at Jurassic level are typically overlain by Tertiary en-echelon graben systems, often showing characteristic 'hourglass' structures in cross-section. Detailed mapping of these fault structures on 3D seismic data has shown that the Jurassic faults and overlying Tertiary faults areoften partially decoupled.Fault throw distributions indicate that the Mio-Pliocene faults have grown downwards instead of Jurassic faults propagating upwards during reactivation. The two fault systems are soft-linked within Cretaceous claystones, only locally linking to form through-going faults. Hydrocarbon leakage pathways are most likely located at these points where critically stressed parts of Jurassic faults link up with Tertiary faults. The position of these linkage zones in relation to structural closure is key to understanding the distribution of preserved and breached columns that have been observed to date.The integration of 3D seismic fault plane mapping with in-situ stress analysis from borehole image and pressure test data provides a valuable tool for the evaluation of trap integrity, potential hydrocarbon leak paths and a more accurate risk assessment of exploration prospects.

Alternatives in Paleocene exploration West of Shetland: a case study

2004 ◽  
Vol 40 (2) ◽  
pp. 131-143 ◽  
Author(s):  
John R. Smallwood ◽  
David Prescott ◽  
Wayne Kirk
Keyword(s):  
Seismic Data ◽  
Seismic Attributes ◽  
Well Testing ◽  
3D Seismic ◽  
Seismic Amplitude ◽  
Magnetic Fabrics ◽  
3D Data ◽  
History Of ◽  
The Uk

SynopsisThis paper illustrates oil exploration in the West of Shetlands area from 1995 to 2001 by documenting the history of Block 205/9, awarded in the UK 16th Licensing Round in 1995. Good quality Paleocene sands had been encountered in the 1989 well 205/9-1 in the down-dip part of the block, and equivalent sands were absent on the adjacent Flett Ridge to the SE, setting up the possibility of a pinchout play. The first well testing the play, 205/8-1, was drilled on the overall pinchout on 2D seismic data, but 3D seismic data were acquired across the area to better delineate the depositional systems. The first well drilled on the 3D data to test the sand pinchout, 205/14-3, failed to encounter sands in communication with those in 205/9-1, so attention turned to alternative stratigraphic traps highlighted by seismic amplitude anomalies. Detailed evaluation of the seismic data revealed that the attractive seismic amplitude response of one potential prospect was actually an artefact associated with overlying basalt. Further analysis of the 3D seismic attributes identified a tongue of sand south of 205/9-1, and analysis of magnetic fabrics from core data in 205/9-1 revealed that sand was input to this area from the NE, contrary to previous models. Unfortunately the seismic attributes, supported by fluid inclusion data, suggested that the sand was water-wet. As a result of the evaluation work, the block was relinquished in 1999 without further drilling. While there is undoubtedly scope for stratigraphic traps in the area to prove hydrocarbon-bearing, experience on the 205/9 block and other studies led to a refocusing on dip-closed structures, and a resulting discovery, the first in the Faroes, consisted of 170 m of hydrocarbon-bearing sands in the T10 Paleocene interval.

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