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Oil crack reservoir inversion method based on matrix-fluid-crack decoupling

A fractured reservoir and fluid technology, applied in the field of physical inversion, can solve problems such as incorrect fluid indicator factor estimation and influence

Active Publication Date: 2020-01-03
CENT SOUTH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Moreover, an incorrect ratio of shear and compressional wave velocities may have a significant impact on the estimation of the fluid indicator factor
Currently there is no effective method for seismic fracture characteristics and fluid identification in fluid-saturated fractured reservoirs

Method used

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  • Oil crack reservoir inversion method based on matrix-fluid-crack decoupling
  • Oil crack reservoir inversion method based on matrix-fluid-crack decoupling
  • Oil crack reservoir inversion method based on matrix-fluid-crack decoupling

Examples

Experimental program
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Effect test

Embodiment 1

[0095] see Figure 1a ~ Figure 1f , an inversion method for oily fractured reservoirs based on matrix-fluid-fracture decoupling, including the following steps: using the Born approximation theory and the first-order perturbation assumption, deduce the Based on the linearized PP wave reflection coefficient of matrix-fluid-fracture decoupling, the combined effects of rock background matrix, pore fluid and fracture strength on seismic reflection amplitude can be separated in the derived formula. Using geological data and logging data as prior information, azimuth pre-stack inversion is realized by stacking azimuth seismic data with partial incidence angles, and the rock background matrix elastic modulus, fluid bulk modulus and Fracture weakness, so as to realize fluid identification and fracture detection of fluid-saturated fractured reservoirs.

[0096] Based on the linear sliding model, the flexibility matrix S of fluid-saturated fractured rock sat can be expressed as the fl...

Embodiment 2

[0182]Referring to Figures 2-6, this example uses a well log model to demonstrate the proposed two-step inversion method to estimate the effective pore fluid bulk modulus, dry rock matrix, and saturated fracture weakness. Synthetic seismic angle gathers at different azimuths are generated using the convolutional model and estimated seismic wavelets.

[0183] Figure 2a It is a noise-free seismic gather synthesized at different azimuth angles, the azimuth angles are 30°, 60°, 90° and 120° respectively, and the incident angle varies from 0° to 40°. In order to illustrate the robustness of the proposed inversion method, this embodiment also adds Gaussian random noise with different SNRs (the SNRs are 5 and 2, respectively) to generate noisy azimuth gathers, as shown in Figure 2b and 2c.

[0184] Figure 3a and Figure 3b The real and inverted values ​​of the model parameters are given, and the results show that the estimation of the model parameters is reasonable in the case...

Embodiment 3

[0188] Referring to Figures 7 to 10, this example uses the actual data in eastern my country and uses a two-step inversion method to estimate the effective pore fluid bulk modulus, dry rock matrix and saturated fracture weakness, and verifies the results of the present invention. effectiveness of the method described.

[0189] Figure 7a -7d is the stacked seismic profile of different azimuth angles, the azimuth angles are 0° (the range between -30°-30°), 45° (the range between 15°-75°), 90° (the range between 60° range between -120°), 135° (range between 105°-165°). For each azimuth data, the average angle of incidence for each common midpoint profile (CMP) gather is 12° (range between 4°-20°), 24° (range between 16°-32°) 36° (range between 28°-44°).

[0190] Then, the model-based LS inversion of the azimuthal elastic impedance, Figure 8a -8d shows the inverted EI profiles at different azimuth angles.

[0191] Finally, Bayesian inversion is performed on the model paramet...

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Abstract

The invention provides an oil crack reservoir inversion method based on matrix-fluid-crack decoupling. The method comprises the steps that firstly, a Born approximation theory and a first-order disturbance hypothesis are utilized to derive a linearized PP wave reflection coefficient at a horizontal transverse isotropic medium interface of two filling saturated fluids based on matrix-fluid-crack decoupling; and secondly, geological data and logging data are used as prior information, partial incident angle superposition azimuth seismic data is utilized to realize azimuth prestack inversion, a rock background matrix elasticity modulus, a fluid volume modulus and crack weakness in a Bayesian framework are estimated according to an inversion result, and therefore fluid recognition and crack detection on a saturated fluid crack type reservoir are realized. According to the method, compared with other fluid indication factors, dual influences of rock porosity and pore fluids can be eliminated by using the effective pore fluid volume modulus as one fluid indication factor, and therefore the reservoir fluids can be recognized more effectively.

Description

technical field [0001] The invention relates to the technical field of physical inversion, in particular to an oil-bearing fracture reservoir inversion method based on matrix-fluid-fracture decoupling. Background technique [0002] The velocity of seismic waves propagating in a horizontal transverse isotropic (HTI) medium varies with different directions. The azimuth velocity changes during the propagation of seismic waves in this HTI medium, and the anisotropy defined by the fluid bulk modulus and fracture weakness can characterize the azimuth velocity variation. [0003] The normal-tangential fracture compliance ratio is the product of the two ratios of shear and compressional wave velocities and normal-tangential fracture weakness, and is often used as an indicator of fracture fluid in oil and gas reservoirs. However, this fluid indicator factor depends on both fluid saturation and fracture strength. Moreover, the incorrect ratio of shear and compressional wave velociti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/30
CPCG01V1/30G01V1/306G01V1/307G01V2210/624G01V2210/63
Inventor 潘新朋柳卓柳建新崔益安郭振威
Owner CENT SOUTH UNIV
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