Manifestation of Fluid Saturation in Scattererd Waves – Numerical Experiments and Field Study
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Vladimir A. Tcheverda 1, Vadim V. Lisitsa 1,
Galina V. Reshetova 1.
Anastaiya S. Merzlikina 2, Valery V. Shilikov 2.
Vladimir A. Pozdnyakov 3.
1 – Institute of petroleum Geology and Geophysics SB RAS, Novosibirsk
2 – Rosneft Krasnoyarsk
3 – Siberian Federal University, Russia
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This study is done thanks to PRACE* Access Grant # 2012071274: 32 million core-hours on supercomputer HERMIT at Stuttgart University
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Acknowledgements:
* Partnership for Advanced Computing in Europe
Content
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1.Carbonate reservoirs. Fracture corridors.2.Scattered waves.3.Scattered waves’ simulation
Content
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1.Carbonate reservoirs. Fracture corridors.2.Scattered waves.3.Scattered waves’ simulation
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“It is estimated that more than 60% of the world's oil and 40% of the world's gas reserves are held in carbonate reservoirs.”
(http://www.slb.com/services/technical_challenges/carbonates.aspx)
Oil in carbonate reservoirs
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Oil in carbonate reservoirs
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Oil in carbonate reservoirs
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Acquisitions and deep wells
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Common situation for reservoirs in the carbonate environment: oil is accumulated in caverns, but permeability is determined mainly by fractures. Rock matrix is not permeable.
Cavernous/fractured reservoirs
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Core samples from Yurubcheno-Tohomskoe oil fieldNo cavities With cavities
FC – fracture corridors
BFC – bed controlled fracture
MBF – multibed fractures
HPF – highly persistent fractures
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Variety of fractures in the carbonate environment (following J.-P.Petit et al.)
Fracture corridors
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Recovery of fracture corridors is of great importance in order to ensure effective oil field development.
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Uncovered (outcrop) fracture corridor
Content
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1.Carbonate reservoirs. Fracture corridors.2.Scattered waves.3.Scattered waves’ simulation.
Scattered waves
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Regular seismic technology based on reflected waves cannot reconstruct the fine structure of a fractured reservoir:resolution of standard seismic techniques is of a few meters at best, while the typical thickness of fracture corridors does not exceed a few tens of centimeters. Fortunately, these objects generate scattered waves which can deliver important knowledge about fine interior of hydrocarbon collectors.
Scattered waves and fracture orientation
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Model (thanks to Pierre Thore)
Closer look, top
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Closer look, x-line
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Closer look, in-line
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Wavefield inside the reservoir, top view
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Wavefield inside the reservoir, top view.
P-wave scattering
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Wavefield inside the reservoir, top view.
S-wave scattering
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Wavefield, x-line view
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Wavefield, x-line view
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Wavefield, in-line view
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In-line Cross-line
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Azimuth distribution of scattering energy
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Azimuth distribution of scattering energy and fracture orientation: Real data
Distribution of fractures in the well by FMI (Formation MicroImager) scanner
Azimuth distribution of scattered energy
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Scattered waves and fluid saturation
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Real life cubes
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Seismic cubes Permeability
Fluid saturation and scattered waves
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Fluid saturation and scattered waves: synthetic
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Fluid saturation and scattered waves: real data
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Fluid saturation and scattered waves: real data
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Fluid saturation and scattered waves: real life prognostic geological map
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Fluid saturation and scattered waves
Core sample
Image in scattered waves
Multiple scattering
Content
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1.Carbonate reservoirs. Fracture corridors.2.Scattered waves.3.Scattered waves’ simulation.
Scattered waves’ simulation
Simulation of wave propagation in realistic 3D anisotropic, viscoelastic media taking into account microstructure (fractures, cracks, caverns etc.) to
get a knowledge about scattered energy.
How are we doing this?
Time domain explicit finite-differences methods with local grid refinement in time and space.
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ll
l
lL
l
T
rCt
r
rCt
uut
t
u
2,
1=1
=
=
=
=
First order system of viscoelastic wave equations
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Artifacts
Artificial reflections must be around
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Estimated amplitude of scattered waves (theory of single scattering) is about 0.001
– 0.01 with respect to the incident one!!
Local grid refinement
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1. Fine grid should be used only where \caverns\cracks\fractures are presented in order to avoid unrealistic demands on computer resources.
2. Different grids cause artificial reflections due to different numerical dispersion.
3. These artificial reflections must be around 10-3 - 10-4 with respect to incident wave.
4. Finite-difference scheme must be stable.
Local grid refinement
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1. Grid refinement in time and space is performed by turn:
Parallel implementation via domain decomposition
Fine-grid area can be placed anywhere within the reference model regardless to the specific domain decomposition used in coarse-grid model.
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Groups of PU: data exchange
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Scalability
1. Optimal 3D Domain Decomposition via METIS - Serial Graph Partitioning and Fill-reducing Matrix Ordering.
2. Non-blocking send/receive procedures.3. Computations are starting from the most
interior point and are expanding towards neighboring domain
4. Send/Receive of partially sampled data
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Scalability
Strong scalability (acceleration): the size of a problem is fixed, but the number of cores increased.
Ideal acceleration: N x time(N) = const, N – number of cores.
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Strong scalability (acceleration)
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Scalability
Weak scalability: the CPU load is fixed, but the number of cores increased.
Ideal WS: time(N) = const,
N – number of cores.
Weak scalability
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Road map
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1. Development of the archive with a set of realistic synthetic models (macro+mezo+micro scales).
2. Numerical simulation of multiphysics processes: isotropy+anisotropy+attenuation+fluid saturation+fluid flow induced by seismic waves (Permeability?) +……
3. Scattering imaging and inversion4. Non-linear effects of seismic waves’ propagation
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Thank you for attention! Please, ask your questions!