Removal of fracture-induced anisotropy from converted-wave seismic amplitudes

Patent metadata

Field	Value
Publication number	US-9316757-B2
Application number	US-201214353745-A
Country	US
Kind code	B2
Filing date	Oct 9, 2012
Priority date	Dec 6, 2011
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

The present disclosure provides a system and method for inferring one or more physical property parameters of a subsurface media by inverting converted wave data acquired during a seismic survey. Composite seismic traces are generated at a plurality of survey azimuths (step 609 ). These composite traces are composed such that their amplitudes are free of effects of subsurface anisotropy. At least one of the generated composite seismic traces is then inverted by isotropic inversion to determine a property parameter of the subsurface media (step 623 ).

First claim

What is claimed is:

1. A method for inferring one or more physical property parameters of a subsurface media by inverting converted wave data acquired during a seismic survey, comprising:
generating a composite seismic trace at a plurality of survey azimuths, said composite traces being composed such that their amplitudes are free of effects of subsurface anisotropy; and
inverting at least one composite seismic trace by isotropic inversion to determine a property parameter of the subsurface media.

2. The method of claim 1 further comprising stacking the composite traces at all survey azimuths to generate a full-azimuth stack and inverting said full-azimuth stack by isotropic inversion.

3. The method of claim 1 further comprising stacking the composite traces at a plurality of survey azimuths to generate a multi-azimuth stack and inverting said multi-azimuth stack by isotropic inversion.

4. The method of claim 1 , wherein each composite trace is a sum of time-adjusted PS 11 mode data and PS 22 mode data from orthogonal azimuths, the PS 11 and PS 22 mode data is generated by performing a tensor rotation on the radial and transverse components of the S-wave data, the PS 11 mode data and PS 22 mode data is time-adjusted by applying either a positive time-shift on the PS 22 mode data or a negative time-shift on the PS 11 mode data.

5. The method of claim 4 , wherein the tensor rotation process utilizes an equation that can be expressed as

[

PS
11
ϕ

PS
12
ϕ

PS
21
ϕ

PS
22
ϕ

]

=

[

sin
⁢

⁢
ϕ

cos
⁢

⁢
ϕ

-
cos

⁢

⁢
ϕ

sin
⁢

⁢
ϕ

]

⁡

[

PS
R
ϕ

PS
T
ϕ

PS
T

ϕ
+
90

PS
R

ϕ
+
90

]

⁡

[

sin
⁢

⁢
ϕ

-
cos

⁢

⁢
ϕ

cos
⁢

⁢
ϕ

sin
⁢

⁢
ϕ

]

where φ is the azimuth of the survey, PS R φ and PS T φ are the radial and transverse components of the converted wave seismic data at survey azimuth φ, and PS R φ+90 and PS T φ+90 are radial and transverse components from the orthogonal azimuth φ+90.

6. The method of claim 4 , wherein the inversion process utilizes a formula that can be expressed as

PS

PS
11

+

Assignees

• Bansal Reeshidev
• Matheney Michael P
• Exxonmobil Upstream Res Co

Inventors

• Bansal Reeshidev
• Matheney Michael P

Classifications

• G01V1/362

  Effecting static or dynamic corrections; Stacking · CPC title

• G01V1/30 Primary

  Analysis (G01V1/50 takes precedence) · CPC title

• E21B49/00

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• G01V2210/6222

  Velocity; travel time · CPC title

• G01V1/303 Primary

  for determining velocity profiles or travel times · CPC title