On: “Lithology discrimination for thin layers using wavelet signal parameters” by J. N. Lange and H. A. Almoghrabi (GEOPHYSICS, 53, 1512–1519, December 1988).

Geophysics ◽  
1989 ◽  
Vol 54 (6) ◽  
pp. 789-789 ◽  
Author(s):  
M. K. Sengupta
Keyword(s):  
Pore Fluid ◽  
Thin Layers ◽  
Fluid Type ◽  
Frequency Dependent ◽  
Signal Parameters

Lange and Almoghrabi have shown correctly that seismic frequency is an important parameter for discriminating among seismic lithologies and pore‐fluid types for thin layers. I would like to draw attention to Figure 3 of this paper and to the last paragraph of their conclusions, which state, “The crux of the multiparameter algorithms…is the thin layer’s frequency‐dependent reflectivity, which can be used to discriminate reflector lithologies and pore fluid type.”

Lithology discrimination for thin layers using wavelet signal parameters

Geophysics ◽  
1988 ◽  
Vol 53 (12) ◽  
pp. 1512-1519 ◽  
Author(s):  
James N. Lange ◽  
H. A. Almoghrabi
Keyword(s):  
Thin Layer ◽  
Frequency Domain ◽  
Prior Knowledge ◽  
Characteristic Frequency ◽  
Forward Modeling ◽  
Pore Fluid ◽  
Thin Layers ◽  
Modeling Technique ◽  
Fluid Type ◽  
Signal Parameters

A forward modeling technique using Ricker wavelets demonstrates the need for a multiparameter approach in lithology determination using reflections from thin layers. The combination of time‐ and frequency‐domain analyses leads to a set of algorithms which define pore fluid and lithology from wavelet characteristics. The dispersive behavior of the thin layer varies considerably with the environment surrounding the layer, resulting in characteristic frequency‐domain behavior. With a limited prior knowledge of the formation environment, the pore fluid type can be determined using mode‐converted waves in the frequency domain.

Reply by the authors to M. K. Sengupta

Geophysics ◽  
1989 ◽  
Vol 54 (6) ◽  
pp. 789-789
Author(s):  
James N. Lange ◽  
Hamzah A. Almoghrabi
Keyword(s):  
Frequency Domain ◽  
Pore Fluid ◽  
Thin Layers ◽  
P Wave ◽  
Wave Frequency ◽  
Fluid Type ◽  
S Wave ◽  
S Waves ◽  
Domain Information

The method presented in M. Sengupta’s patent provides a means of displaying both frequency and offset information necessary to evaluate the response of thin layers. Although it is developed to view P‐wave behavior, an adaptation of the technique might provide frequency‐domain information on mode‐converted S‐waves. Comparison of the P‐wave and mode‐converted S‐wave frequency‐domain behaviors yields important information on the lithology and pore‐fluid type of thin layers, as shown in Figure 11 of our paper.

scholarly journals Fluid Discrimination Based on Frequency-Dependent AVO Inversion with the Elastic Parameter Sensitivity Analysis

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Pu Wang ◽  
Jingye Li ◽  
Xiaohong Chen ◽  
Kedong Wang ◽  
Benfeng Wang
Keyword(s):  
Data Interpretation ◽  
Elastic Parameter ◽  
Pore Fluid ◽  
P Wave ◽  
Frequency Dependent ◽  
Avo Inversion ◽  
Fluid Factor ◽  
Dispersion Terms ◽  
Dispersion And Attenuation ◽  
Dispersion Term

Fluid discrimination is an extremely important part of seismic data interpretation. It plays an important role in the refined description of hydrocarbon-bearing reservoirs. The conventional AVO inversion based on Zoeppritz’s equation shows potential in lithology prediction and fluid discrimination; however, the dispersion and attenuation induced by pore fluid are not fully considered. The relationship between dispersion terms in different frequency-dependent AVO equations has not yet been discussed. Following the arguments of Chapman, the influence of pore fluid on elastic parameters is analyzed in detail. We find that the dispersion and attenuation of Russell fluid factor, Lamé parameter, and bulk modulus are more pronounced than those of P-wave modulus. The Russell fluid factor is most prominent among them. Based on frequency-dependent AVO inversion, the uniform expression of different dispersion terms of these parameters is derived. Then, incorporating the P-wave difference with the dispersion terms, we obtain new P-wave difference dispersion factors which can identify the gas-bearing reservoir location better compared with the dispersion terms. Field data application also shows that the dispersion term of Russell fluid factor is optimal in identifying fluid. However, the dispersion term of Russell fluid factor could be unsatisfactory, if the value of the weighting parameter associated with dry rock is improper. Then, this parameter is studied to propose a reasonable setting range. The results given by this paper are helpful for the fluid discrimination in hydrocarbon-bearing rocks.

Effect of Pore Fluid Type on Perforation Damage and Flow Characteristics

2001 ◽  
Author(s):  
C. Ozgen Karacan ◽  
Abraham S. Grader ◽  
Phillip M. Halleck
Keyword(s):  
Flow Characteristics ◽  
Pore Fluid ◽  
Fluid Type

Anisotropic P-SV-wave dispersion and attenuation due to inter-layer flow in thinly layered porous rocks

Geophysics ◽  
2011 ◽  
Vol 76 (3) ◽  
pp. WA135-WA145 ◽  
Author(s):  
Fabian Krzikalla ◽  
Tobias M. Müller
Keyword(s):  
Wave Attenuation ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
P Wave ◽  
Angle Of Incidence ◽  
Porous Rocks ◽  
Frequency Dependent ◽  
Symmetry Properties ◽  
Wave Induced ◽  
Attenuation And Dispersion

Elastic upscaling of thinly layered rocks typically is performed using the established Backus averaging technique. Its poroelastic extension applies to thinly layered fluid-saturated porous rocks and enables the use of anisotropic effective medium models that are valid in the low- and high-frequency limits for relaxed and unrelaxed pore-fluid pressures, respectively. At intermediate frequencies, wave-induced interlayer flow causes attenuation and dispersion beyond that described by Biot’s global flow and microscopic squirt flow. Several models quantify frequency-dependent, normal-incidence P-wave propagation in layered poroelastic media but yield no prediction for arbitrary angles of incidence, or for S-wave-induced interlayer flow. It is shown that generalized models for P-SV-wave attenuation and dispersion as a result of interlayer flow can be constructed by unifying the anisotropic Backus limits with existing P-wave frequency-dependent interlayer flow models. The construction principle is exact and is based on the symmetry properties of the effective elastic relaxation tensor governing the pore-fluid pressure diffusion. These new theories quantify anisotropic P- and SV-wave attenuation and velocity dispersion. The maximum SV-wave attenuation is of the same order of magnitude as the maximum P-wave attenuation and occurs prominently around an angle of incidence of [Formula: see text]. For the particular case of a periodically layered medium, the theoretical predictions are confirmed through numerical simulations.

scholarly journals Subcell Modeling of Frequency-Dependent Thin Layers in the FDTD Method

2017 ◽  
Vol 65 (1) ◽  
pp. 278-286 ◽  
Author(s):  
Kenan Tekbas ◽  
Fumie Costen ◽  
Jean-Pierre Berenger ◽  
Ryutaro Himeno ◽  
Hideo Yokota
Keyword(s):  
Fdtd Method ◽  
Thin Layers ◽  
Frequency Dependent

Time-average equation revisited

Geophysics ◽  
1998 ◽  
Vol 63 (2) ◽  
pp. 460-464 ◽  
Author(s):  
Jack Dvorkin ◽  
Amos Nur
Keyword(s):  
Solid Phase ◽  
Rock Physics ◽  
Pore Fluid ◽  
P Wave ◽  
Well Logs ◽  
Fluid Type ◽  
Wave Velocities ◽  
P Wave Velocity ◽  
Solid Phase Material

Expressions that relate velocity to porosity and to pore-fluid compressibility are among the most important deliverables of rock physics. Such relations are used often as additional controls for inferring porosity from well logs, as well as in-situ indicators of pore fluid type. The oldest and most popular is the Wyllie et al. (1956) equation: [Formula: see text]where [Formula: see text] is the measured traveltime of a P-wave, [Formula: see text] is the traveltime expected in the solid-phase material, and [Formula: see text] is the traveltime expected in the pore fluid. It follows from equation (1) that [Formula: see text]where ϕ is porosity, [Formula: see text] is the measured P-wave velocity, and [Formula: see text] and [Formula: see text] are the P-wave velocities in the solid and in the pore-fluid phases, respectively.

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