3D seismic characterization of fractures with random spacing using the double-beam method

Geophysics ◽  
2018 ◽  
Vol 83 (5) ◽  
pp. M63-M74 ◽  
Author(s):  
Hao Hu ◽  
Yingcai Zheng ◽  
Xinding Fang ◽  
Michael C. Fehler
Keyword(s):  
Fluid Transport ◽  
Spatial Location ◽  
Characterization Methods ◽  
Fracture Spacing ◽  
Fracture Orientation ◽  
Double Beam ◽  
Beam Method ◽  
Seismic Characterization ◽  
Subsurface Fractures ◽  
Induced Fractures

Obtaining information on the spatial distribution of subsurface natural and induced fractures is critical in the production of geothermal or hydrocarbon fluids. Traditional seismic characterization methods for subsurface fractures are based on the assumption of effective anisotropy medium theory, which may not be true in reality when the fracture distribution is random. We have tested the recently proposed double-beam method to characterize nonuniformly distributed fractures. We built a 3D layered reservoir model; the reservoir layer was geometrically irregular, and it contained a set of randomly spaced fractures with spatially varying fracture compliances. We used an elastic full-wave finite-difference method to model the wavefield, where we treat the fractures as linear-slip boundaries and the data include all elastic multiple scattering. Taking the surface seismic data as input, the double-beam method forms a focusing source beam and a focusing receiver beam toward the fracture target. The fracture information is derived from the interference pattern of these two beams, which includes fracture orientation, fracture spacing, and fracture compliance as a function of spatial location. The fracture orientation parameter is the most readily determined parameter even for multiple nonorthogonal coexistent fracture sets. The beam-interference amplitude depends on the fracture spacing and compliance in a local average sense for random fractures. The beam-interference amplitude is large when there are many fractures or the compliance value is large, which is important in the interpretation of the fluid-transport properties of a reservoir.

3D seismic characterization of fractures in a dipping layer using the double-beam method

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. V123-V134 ◽  
Author(s):  
Hao Hu ◽  
Yingcai Zheng
Keyword(s):  
Fracture Network ◽  
New Method ◽  
Fractured Reservoir ◽  
Fracture Spacing ◽  
Fracture Orientation ◽  
Double Beam ◽  
Beam Method ◽  
Seismic Characterization ◽  
Dip Angle

The characterization of natural and induced fractures, in terms of fracture orientation, fracture spacing (or density), and fracture compliance, is critical in reservoir development. Given the multiscale nature of the fracture distribution, the commonly used effective anisotropy assumption may not be valid. The recently proposed double-beam method to characterize the fractured reservoir has the potential to invert for the spatially dependent fracture network information for a horizontal reservoir layer. However, the inverted results can be biased if the fractured reservoir layer is dipping. As a result, it is essential to estimate and include the dip-angle information of reservoir layers in applying the double-beam method. We used forward modeling to demonstrate the bias, and we developed a new method to correct for the error caused by the reservoir layer dip angle. For a dipping layer, our new method can correctly invert for the fracture parameters, including the fracture orientation and fracture spacing.

A Semianalytic Solution for Temporal Pressure and Production Rate in a Shale Reservoir With Nonuniform Distribution of Induced Fractures

SPE Journal ◽  
2019 ◽  
Vol 24 (04) ◽  
pp. 1856-1883 ◽  
Author(s):  
Guanglong Sheng ◽  
Farzam Javadpour ◽  
Yuliang Su ◽  
Jinghua Liu ◽  
Kunjie Li ◽  
...  
Keyword(s):  
Production Rate ◽  
Early Time ◽  
Fractal Model ◽  
Fracture Density ◽  
Fracture Networks ◽  
Fracture Spacing ◽  
Fractal Distribution ◽  
Diffusivity Equation ◽  
Induced Fractures ◽  
Fracture Distribution

Summary The network of induced fractures and their properties control pressure propagation and fluid flow in hydraulically fractured shale reservoirs. We present a novel fully fractal model in which both the spacing and the porosity/permeability of induced fractures are distributed according to fractal dimensions (i.e., fractal decay of fracture density and the associated porosity/permeability away from the main induced fracture). The fractal fracture distribution is general, and handles exponential, linear, power, and uniform distributions. We also developed a new fully fractal diffusivity equation (FDE) using the fractal distribution of fractures and their properties. We then used, for the first time, the semianalytic Bessel spline scheme to solve the developed diffusivity equation. Our proposed model is general and can capture any form of induced-fracture distribution for better analysis of pressure response and production rates at transient- and pseudosteady-state conditions. We compared the unsteady-state and pseudosteady-state pressure responses calculated by our fully fractal model with former models of limited cases: uniform fracture spacing and uniform porosity/permeability [conventional diffusivity equation (CDE)]; variable fracture spacing and uniform porosity/permeability [modified CDE (MCDE)]; and uniform fracture spacing and fractal porosity/permeability distribution (FPPD). We used these models to match and predict the production data of a multifractured horizontal gas well in the Barnett Shale. Our results showed that the fractal distribution of fracture networks and their associated properties better matches the field data. Uniform distribution of induced-fracture networks underestimates production rate, especially at early time.

scholarly journals Development and Calibration of a Semianalytic Model for Shale Wells with Nonuniform Distribution of Induced Fractures Based on ES-MDA Method

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3718 ◽  
Author(s):  
Qi Zhang ◽  
Shu Jiang ◽  
Xinyue Wu ◽  
Yan Wang ◽  
Qingbang Meng
Keyword(s):  
Shale Gas ◽  
Fractal Dimensions ◽  
Nonuniform Distribution ◽  
Fracture System ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Unconventional Gas ◽  
Fracture Spacing ◽  
Unconventional Gas Reservoirs ◽  
Induced Fractures

Given reliable parameters, a newly developed semianalytic model could offer an efficient option to predict the performance of the multi-fractured horizontal wells (MFHWs) in unconventional gas reservoirs. However, two major challenges come from the accurate description and significant parameters uncertainty of stimulated reservoir volume (SRV). The objective of this work is to develop and calibrate a semianalytic model using the ensemble smoother with multiple data assimilation (ES-MDA) method for the uncertainty reduction in the description and forecasting of MFHWs with nonuniform distribution of induced fractures. The fractal dimensions of induced-fracture spacing (dfs) and aperture (dfa) and tortuosity index of induced-fracture system (θ) are included based on fractal theory to describe the properties of SRV region. Additionally, for shale gas reservoirs, gas transport mechanisms, e.g., viscous flow with slippage, Knudsen diffusion, and surface diffusion, among multi-media including porous kerogen, inorganic matter, and fracture system are taken into account and the model is verified. Then, the effects of the fractal dimensions and tortuosity index of induced fractures on MFHWs performances are analyzed. What follows is employing the ES-MDA method with the presented model to reduce uncertainty in the forecasting of gas production rate for MFHWs in unconventional gas reservoirs using a synthetic case for the tight gas reservoir and a real field case for the shale gas reservoir. The results show that when the fractal dimensions of induced-fracture spacing and aperture is smaller than 2.0 or the tortuosity index of induced-fracture system is larger than 0, the permeability of induced-fracture system decreases with the increase of the distance from hydraulic fractures (HFs) in SRV region. The large dfs or small θ causes the small average permeability of the induced-fracture system, which results in large dimensionless pseudo-pressure and small dimensionless production rate. The matching results indicate that the proposed method could enrich the application of the semianalytic model in the practical field.

scholarly journals A double-beam method for two-photon ionization detection in liquid chromatography.

1984 ◽  
Vol 33 (1) ◽  
pp. E37-E40 ◽  
Author(s):  
Sunao YAMADA ◽  
Atsushi HINO ◽  
Teiichiro OGAWA
Keyword(s):  
Liquid Chromatography ◽  
Two Photon ◽  
Ionization Detection ◽  
Double Beam ◽  
Beam Method ◽  
Photon Ionization

A double-beam method of spectral selection with flames

1955 ◽  
Vol 4 (1) ◽  
pp. 289-299 ◽  
Author(s):  
C. T. J. Alkemade ◽  
J. M. W. Milatz
Keyword(s):  
Double Beam ◽  
Beam Method ◽  
Spectral Selection

scholarly journals Seismic characterization of multiple fracture sets at Rulison Field, Colorado

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. B19-B30 ◽  
Author(s):  
Ivan Vasconcelos ◽  
Vladimir Grechka
Keyword(s):  
Velocity Model ◽  
Multiple Fracture ◽  
Fracture Characterization ◽  
Seismic Reflection Data ◽  
Characterization Methods ◽  
S Waves ◽  
Reflection Data ◽  
Seismic Characterization ◽  
Inversion Procedure

Conventional fracture-characterization methods assume the presence of a single set of aligned, vertical cracks in the subsur-face. We relax this assumption and demonstrate the feasibility of seismic characterization of multiple fracture sets. Our technique relies on recent numerical findings indicating that multiple, differently oriented, possibly intersecting planar cracks embedded in an otherwise isotropic host rock result in a nearly orthorhombic (or orthotropic) effective medium. Here, the governing parameters of crack-induced orthotropy are estimated from 3D, wide-azimuth, multicomponent seismic reflection data acquired over the tight-gas Rulison Field in Colorado. We translate strong azimuthal variations of the normal-moveout velocities intointerval crack densities, fracture orientations, type of fluid infill, and velocities of P- and S-waves in an unfractured rock. Our inversion procedure identifies a set of cracks aligned in approximately west northwest-east southeast direction in the western part of the study area and multiple, likely intersecting fractures in its eastern part. We validate both our underlying theoretical model and the obtained estimates by two independent measurements: (1) the estimated fluid-infill parameter indicates dry cracks as expected for the gas-producing sandstones at Rulison; and (2) the obtained crack orientations are supported by well observations. As a by-product of fracture characterization, we build an anisotropic velocity model of the Rulison reservoir which, we believe, is the first orthorhombic velocity field constructed from surface seismic data.

Spectral intensity measurement by double beam method

1970 ◽  
Vol 19 (3) ◽  
pp. 318-324 ◽  
Author(s):  
Hiroto ISAGAWA ◽  
Eiji NIKI
Keyword(s):  
Intensity Measurement ◽  
Spectral Intensity ◽  
Double Beam ◽  
Beam Method
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