Azimuthal anisotropy analysis from P‐wave seismic traveltime data

Craft, Kenneth L.; Mallick, Subhashis; Meister, Laurent; Dok, Richard Van

doi:10.1190/1.1885615

Cited by 28 publications

(16 citation statements)

References 2 publications

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“…They found small, but definite stacking velocity anisotropy, which was consistent with Chen's results and the known fracture trend. Similar results have been reported elsewhere by Blackhawk Geosciences (1995), Lynn et al (1996), Craft et al (1997), and others.…”

Section: P-wave Stacking Velocity Anisotropysupporting

confidence: 80%

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Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Mavko¹

2000

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JUSTIFICATIONDuring Phase I, we performed our rock physics, geologic, and seismic feasibility analysis for fracture characterization. We addressed the problem of seismic fracture detection and characterization, in general, and specifically at our field site in West Texas. In this analysis, we were able to implement a number of fracture modeling procedures and to quantitatively assess the theoretical detectability of reservoir fractures. This allowed us to identify which of the several seismic attributes are most likely to be useful for fracture detection at the site. One of our results showed that Thomsen's parameters should be very useful for indicating gas-filled fractures at the site. We also outlined Monte Carlo approaches that can be applied for feasibility analysis at any site.Prior to our study, most seismic fracture detection methods have focused on qualitatively detecting seismic anisotropy. While anisotropy is critical, when used alone it has left us with interpretation ambiguities and nonuniqueness. During Phase 1 of this project, we found that by statistically integrating geologic and seismic information we can develop nontraditional methods for fracture detection. For example, we found that quantifying the correlations between fracture occurrence and depositional environment, and between fracture spacing and layer thickness, we allow us to decrease the uncertainty of fracture interpretation using seismic anisotropy. One of the reasons for this is that different depositional environments (and rock facies) give rise to differences in their seismic signatures (impedances, velocities, and Poisson's ratio.Phase II will allow us to validate and improve these methodologies by carrying out a smallscale field pilot study. Taking methods to the field, always allows us to make them more applicable. In the field, we will be able to more accurately assess the uncertainties introduced by measurement noise, source and receiver response, coupling, and near surface acoustic properties. We can then more realistically develop ways to reduce the uncertainty, as well as to identify which aspects of the geology and fracture distribution we can characterize most robustly. The small-scale field study will also help us to establish empirical fracture parameters that are needed as inputs to rock physics models. For example, ALL of the effective medium models for fracture-induced anisotropy require fracture stiffness as inputs (these are sometimes characterized as moduli or aspect ratios). There is no realistic way to assign these values DOE FINAL TECHNICAL REPORT ON PHASE 4 theoretically, so being able to calibrate them in a small pilot will give us the critical inputs we need for interpreting the full scale seismic survey in phase III. Finally, the data from the pilot will allow us to add an aspect of "data mining" to the study. In Phase I, we have exploited our best theoretical tools, but the real field data will give us the opportunity to discover other, unpredicted, signatures of fractures that might prove valuable.Our a...

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Section: P-wave Stacking Velocity Anisotropysupporting

confidence: 80%

“…The azimuth of vertical fractures is assumed to lie in the direction of maximum stacking velocity. Details are discussed by Craft, et al (1997).…”

Section: Western's Fractogrammentioning

confidence: 99%

Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Mavko¹

2000

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“…This method has obtained reliable results (Mallick, et al, 1998;Craft, et al, 1997). Figure 1 summarizes the method of fracture detection by P wave amplitude and velocity.…”

Section: Principle Of Full Azimuth P Wave Fracture Detection Methodsmentioning

confidence: 85%

“…As there are some shortcomings above mentioned in the application of S wave data for fracture detection, the conclusion of recent studies (Mallick and Frazer, 1991;Mallick et al, 1996Mallick et al, , 1998Craft et al, 1997) is analyze the P wave reflection amplitude or velocity variations with azimuth and offset, using AVA and VVA to estimate the strike and density of the fractures. This method has obtained reliable results (Mallick, et al, 1998;Craft, et al, 1997).…”

Section: Principle Of Full Azimuth P Wave Fracture Detection Methodsmentioning

confidence: 99%

Fracture detection by using full azimuth P wave attributes

Wang

et al. 2007

Appl. Geophys.

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A type of specific fractured hydrocarbon reservoir, a shale fractured reservoir, exists in the Shengli oilfield. Due to very small porosity of this type, low sensitivity to the variation of petrochemical property parameters, and strong anisotropy, it is very difficult to explore for them. So far, there is no set of mature methods for recognition of direction, distribution, and density of the fractures by an integrated analysis of geologic, geophysical, well log, drilling data, and etc. This paper presents a new method for acoustic impedance variation with azimuth (IPVA), based on existing fracture detection methods. Seismic acquisition, processing, and recognition techniques were developed for detecting directional vertical fractures using multi-azimuth P wave data in combination with the seismic and geological features of shale fractures in the Luojia area. The IPVA research is carried out for recognizing the distribution, strike, and density of fractures based on the study of velocity variation with azimuth (VVA) and amplitude variation with azimuth (AVA) for full azimuth P wave data at different CMP positions. Through practical application in the Luojia area, primary results have been obtained which verifies that the IPVA method provides good potential for quantitative detection of parallel, high angle, shale fractures.

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“…A new methodology was developed by Western Geophysical t o allow the azimuthal variations in P-wave anisotropy t o be more finely delineated than k 45" (Mallick et al, 1996;Craft et al, 1997). …”

Azimuthal anisotropy analysis from P‐wave seismic traveltime data

Cited by 28 publications

References 2 publications

Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Fracture detection by using full azimuth P wave attributes

Naturally fractured tight gas reservoir detection optimization. Final report

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