Analyze the Seismic Attributes in HSX Volcanic Fracture Based on Forward Modeling

2014 ◽  
Vol 556-562 ◽  
pp. 899-902
Author(s):  
Yong Wang
Keyword(s):  
Fractured Reservoirs ◽  
Forward Modeling ◽  
Seismic Attributes ◽  
Fractured Media ◽  
Two Dimensional ◽  
Fracture Density ◽  
Seismic Attribute ◽  
Difference Wave ◽  
Depth Migration ◽  
Fracture Models

This paper uses the Hassan Carboniferous fractured reservoirs as the goal, firstly it analyses the reservoir characteristics of the cracks. On this basis, it uses two-dimensional random fractured media modeling method to build three different fracture models with different fracture parameters (fracture density, dip and speed). Then it uses finite difference wave equation forward and pre-stack depth migration processing of these models, and analyses seismic attribute of the migrated data, finally it finds a variety of seismic attributes sensitive to cracks, lays the foundation for fracture prediction with the seismic multi-attributes.

Reliability analysis of seismic attribute in the detection of fault-karst

2020 ◽  
Vol 8 (4) ◽  
pp. SP61-SP70
Author(s):  
Yan Ding ◽  
Qizhen Du ◽  
Liyun Fu ◽  
Shikai Jian
Keyword(s):  
Reliability Analysis ◽  
Seismic Data ◽  
Velocity Model ◽  
Seismic Attributes ◽  
Fracture Density ◽  
Seismic Attribute ◽  
Practical Applications ◽  
Fracture Orientation ◽  
Similarity Estimation ◽  
Phase Variance

In the Tarim Basin, various irregular fractured-vuggy reservoirs have developed along with the main faults. These reservoirs are geologically defined as carbonate fault karst. In the past few years, seismic attributes have been widely used for the identification and evaluation of fault karst. However, there has been less reliability analysis regarding their usage. Imaging using the theoretical fault-karst velocity model can reflect the shapes and distributions of fractures and vugs, whereas imaging using the background velocity can simulate seismic data in real cases. We have adopted an approach based on typical fault-karst theoretical forward modeling to evaluate the reliability of seismic attributes in practical applications. First, we extract various attributes from the images using the theoretical velocity and the background velocity using similarity estimation between them to optimize the sensitive attributes. The analysis result indicates that the instantaneous phase, variance, amplitude gradient, coherence, and texture entropy are more suitable to characterize the anomalies of fractures and vugs with prediction accuracy of 71.7%. Because fracture orientation and density are the key parameters for quantifying the differences between the two images, taking coherence as an example, we extract the fracture traces through circular scanlines and circular windows based on the optimized attributes. The coincidence rate between the predicted fracture density and the known model reaches 83%, and that between the predicted fracture orientation and the known model is greater than 95%. With this remarkable coincidence, we can conclude that optimized seismic attributes are reliable for characterizing fractured-vuggy reservoirs.

Effect of main frequencies on characterizing fault damage zones using forward modeling and attribute of variance

2020 ◽  
Vol 8 (4) ◽  
pp. SP157-SP165
Author(s):  
Yangpu Chen ◽  
Zonghu Liao ◽  
Li-Yun Fu ◽  
Gang Zhou ◽  
Liang Xu ◽  
...  
Keyword(s):  
Damage Zone ◽  
Low Frequency ◽  
Forward Modeling ◽  
Seismic Attributes ◽  
Frequency Effect ◽  
Fracture Density ◽  
Internal Structures ◽  
Fault Structures ◽  
Scattering Noise ◽  
40 Hz

Faulting processes have created large damage zones with complex structures in the field; however, estimating the width and geometry of such fault structures in the subsurface is challenging due to a lack of data. Seismic attributes (e.g., coherence and variance) from seismic surveys have been used for the characterization of faults, but most cases do not detail the effectiveness of this approach. By using forward modeling and the associated seismic attributes of variance, four fault models of idealized damage zones are characterized and the frequency effect is evaluated on the width estimation of fault damage zones in the subsurface. The main results indicate that (1) the general geometric pattern of damage zones could be identified by using simulated amplitude and seismic variance with main frequencies of 10, 25, and 40 Hz; (2) the estimated widths of damage zones at a low frequency of 10 Hz are larger (up to twofold) than those at frequencies of 25 and 40 Hz; for large damage zones (>400 m), the width is best estimated by a frequency of 25 Hz; and (3) scattering noise and diffraction around the fault are found in data at a high frequency of 40 Hz, which results in width overestimation of the damage zones by approximately 17%. The internal structures are difficult to distinguish as scattering noise and chaotic reflections dominate seismic signals. More factors that may influence the accuracy of damage zone width estimation via seismic attributes, include the bedding thickness, fracture density, and velocity. An in-depth understanding of this approach is useful in the application of seismic variance to characterize fault damage zones that may significantly control the fluid migration in the subsurface.

Categorizing and correlating diffractivity attributes with seismic-reflection attributes using autoencoder networks

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. O59-O70
Author(s):  
Sergius Dell ◽  
Jan Walda ◽  
Andreas Hoelker ◽  
Dirk Gajewski
Keyword(s):  
Spectral Decomposition ◽  
Seismic Reflection ◽  
Seismic Attributes ◽  
Learning Approach ◽  
Fracture Density ◽  
Seismic Attribute ◽  
Edge Diffraction ◽  
Time Migration ◽  
Fault Interpretation ◽  
Decomposition Class

Seismic attributes play a crucial role in fault interpretation and mapping fracture density. Conventionally, seismic attributes derived from migrated reflections are used for this purpose. The attributes derived from the other counterparts of the recorded wavefield are often ignored and excluded from the categorization. We have performed categorization of the attributes derived from the diffracted part of the wavefield and combine them into a new seismic attribute class, which we call diffractivity attributes. The extraction of diffractivity attributes is based on the 3D Kirchhoff time migration operator that includes a dynamic muting. We distinguish three major classes in the diffractivity attributes, which describe geometric and amplitude properties of the seismic diffractions. We assign point and edge diffraction focusing as well as the azimuth to the geometric class. The amplitudes of the isolated seismic diffractions are used to extract the instantaneous attributes based on the complex-trace approach. The instantaneous amplitudes, phase, frequency, and sweetness build up the instantaneous attribute class. We perform a spectral decomposition of the isolated diffractions into the isofrequencies using the wavelet approach. The isofrequencies compose the spectral-decomposition class. We also link the new diffractivity class to the conventional seismic reflection attributes. We use a deep learning approach based on convolutional neural networks for classifying and correlating the diffractivity attributes.

scholarly journals Pitfalls and limitations in seismic attribute interpretation of tectonic features

2015 ◽  
Vol 3 (1) ◽  
pp. SB5-SB15 ◽  
Author(s):  
Kurt J. Marfurt ◽  
Tiago M. Alves
Keyword(s):  
Seismic Data ◽  
Seismic Attributes ◽  
Seismic Attribute ◽  
3D Data ◽  
Amplitude Data ◽  
Seismic Sections ◽  
Push Down ◽  
Data Coherence ◽  
Level Of Experience ◽  
Tectonic Features

Seismic attributes are routinely used to accelerate and quantify the interpretation of tectonic features in 3D seismic data. Coherence (or variance) cubes delineate the edges of megablocks and faulted strata, curvature delineates folds and flexures, while spectral components delineate lateral changes in thickness and lithology. Seismic attributes are at their best in extracting subtle and easy to overlook features on high-quality seismic data. However, seismic attributes can also exacerbate otherwise subtle effects such as acquisition footprint and velocity pull-up/push-down, as well as small processing and velocity errors in seismic imaging. As a result, the chance that an interpreter will suffer a pitfall is inversely proportional to his or her experience. Interpreters with a history of making conventional maps from vertical seismic sections will have previously encountered problems associated with acquisition, processing, and imaging. Because they know that attributes are a direct measure of the seismic amplitude data, they are not surprised that such attributes “accurately” represent these familiar errors. Less experienced interpreters may encounter these errors for the first time. Regardless of their level of experience, all interpreters are faced with increasingly larger seismic data volumes in which seismic attributes become valuable tools that aid in mapping and communicating geologic features of interest to their colleagues. In terms of attributes, structural pitfalls fall into two general categories: false structures due to seismic noise and processing errors including velocity pull-up/push-down due to lateral variations in the overburden and errors made in attribute computation by not accounting for structural dip. We evaluate these errors using 3D data volumes and find areas where present-day attributes do not provide the images we want.

A Similarity Solution for Imbibition Process and its Adaptation in Finite Difference Simulation of Fractured Reservoirs

2021 ◽  
Author(s):  
Song Du ◽  
Seong Lee ◽  
Xian-Huan Wen ◽  
Yalchin Efendiev
Keyword(s):  
Numerical Simulation ◽  
Finite Difference ◽  
Similarity Solution ◽  
Capillary Force ◽  
Fractured Reservoirs ◽  
Phase Flow ◽  
Scale Modeling ◽  
Fracture Models ◽  
Multi Phase Flow ◽  
Multi Phase

Abstract The imbibition process due to capillary force is an important mechanism that controls fluid flow between the two domains, matrix and fracture, in naturally or hydraulically fractured reservoirs. Many simulation studies have been done in the past decades to understand the multi-phase flow in the tight and shale formation. Although significant advances have been made in large-scale modeling for both unconventional and conventional fields, the imbibition processes in the fractured reservoirs remains underestimated in numerical simulation, that limits confidence in long-term field production predictions. In the meanwhile, to simulate the near-fracture imbibition process, traditionally very-fine simulation grids have to be applied so that the physical phenomena of small-length scale could be captured. However, this leads to expensive computation cost to simulate full-field models with a large number of fractures. To improve numerical efficiency in field-scale modeling, we propose a similarity solution for the imbibition process that can be incorporated into the traditional finite difference formulation with coarse grid cells. The semi-analytical similarity solutions are validated by comparing with numerical simulation results with fine-scale grids. The comparison clearly indicates that the proposed algorithm accurately represents the flow behaviors in complex fracture models. Furthermore, we adopt the semi-analytical study to hydraulic fracture models using Embedded Discrete Fracture Model (Lee et al., 2001) in our numerical studies at different scales to represent hydraulic fractures that are interconnected. We demonstrate: 1) the imbibition is critical in determining flow behavior in a capillary force dominant model, 2) conventional EDFM has its limitation in capturing sub-cell flow behaviors near fractures, 3) combining the proposed similarity solution and EDFM, we can accurately represent the multi-phase flow near fractures with coarser grids, and 4) it is straightforward to adapt the similarity solution concept in finite-difference simulations for fractured reservoirs

Two-dimensional stratigraphic forward modeling, reconstructing high-relief clinoforms in the northern Taranaki Basin

AAPG Bulletin ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2409-2446 ◽  
Author(s):  
Migdalys Salazar ◽  
Lorena Moscardelli ◽  
Lesli Wood
Keyword(s):  
Forward Modeling ◽  
Two Dimensional

scholarly journals Characterization of reservoir sands using 3D seismic attributes in the coastal swamp area of Niger Delta Basin

2021 ◽  
Author(s):  
Oluwatoyin Khadijat Olaleye ◽  
Pius Adekunle Enikanselu ◽  
Michael Ayuk Ayuk
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Seismic Attributes ◽  
Effective Porosity ◽  
High Porosity ◽  
Hydrocarbon Accumulation ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Niger Delta Basin

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.

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