Arcis 2013 reservoir_bochure_

ASSISTING OUR CLIENTS IN THE DEFINITION OF RESERVOIR GEOMETRY, THE DISTRIBUTION OF PHYSICAL PROPERTY CHARACTERISTICS WITHIN A RESERVOIR, AND IN THE CORRELATION OF ALL AVAILABLE DETAILS, ARCIS OFFERS A STATE-OF-THE-ART SUITE OF SEISMIC RESERVOIR CHARACTERIZATION SERVICES.

Coherence attributes

Curvature attributes

Multi-spectral estimates of curvatures

Reflector convergence

Reflector rotation

Fracture analysis using curvature attributes

Visualization of attributes

Thin-bed reflectivity

Correction for spurious phase via estimation of non-minimum phase wavelet

Rock physics analysis

AVO/LMR analysis

Spectral decomposition

Impedance inversion

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A TGS COMPANY

Reservoir Analysis

Coherence attributesCoherence computes a measure of similarity between adjacent traces. Identification and mapping of channel edges, reefs, faults and fracture systems in 3D volumes becomes so much easier with the coherence volume. Structural and stratigraphic interpretation of seismic data get facilitated by using a coherence volume. Arcis offers coherence computation services based on Energy Ratio algorithm (a modified eigen-decomposition of covariant matrices approach). This algorithm has generated results better than those from the standard semblance as well as eigen-decomposition based algorithms.

Coherence using semblance without dip-steering option

Coherence using Energy Ratio

HIGHLOW HIGHLOW

Coherence using semblance

Coherence using Energy Ratio and structure-oriented filtering

HIGHLOW

HIGHLOW

Data courtesy: Olympic Seismic Ltd., Calgary

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Curvature attributesCurvature attributes measure the degree of bending of seismic reflections along a surface or in a volume and help to improve interpretation and structural understanding of 3D seismic data volumes. Different curvature attributes identify subtle faults, fractures, and other features better than other attribute applications. Arcis offers volume computation of curvature, together with their spectral estimates.

Horizon slice through coherence volume Horizon slice through most-positive curvature volume

Horizon slice through most-negative curvature volume Horizon slice through merged volume comprising coherence, most-positive curvature, and most-negative curvature volumes using transparency

Reservoir Analysiswww.arcis.com

Multi-spectral estimates of curvaturesMulti-spectral curvature estimates can yield both long and short wavelength curvature images, allowing an interpreter to enhance geologic features having different scales. Short-wavelength curvature often delineates details within intense, highly localized fracture systems. Long-wavelength curvature often enhances subtle flexures that are difficult to see in conventional seismic, but are often correlated to fracture zones that are below seismic resolution, as well as to collapse features and diagenetic alterations that results in broader bowls.

Time slices 1160 ms

Coherence

Most-positive(long-wave)

Most-positive(short-wave)

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Reflector convergenceReflector convergence attribute is useful in the interpretation of angular unconformities. It is a measure of the change in reflector normal about a more or less horizontal axis.

Time slices through a coherence volume at (left) t=2.700 s and (right) t=2.670 showing two channel system. The channel is clearly delineated (yellow arrows) in the deeper slice (left) but not at the shallower slice (right).

The same two time slices at (left) t=2.700 s and (right) t=2.670 now co-rendered with reflector convergence. Note the change in convergence towards the edges of the channel within the deeper slice shown in (left) and away from the center of the channel in the shallower section seen in (right).

A’

N

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W E

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N N

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Reflector rotation

Time slice at 1.190 s from the coherence volume and vertical slices through seismic amplitude co-rendered with vector rotation. Red indicates down to the right across the fault, while blue indicates up the right across the fault.

Reflector rotation attribute quantifies the rotation of fault blocks across discontinuities such as wrench faults. It is a measure of the change in reflector normal about a more or less vertical axis.

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Fracture analysis using curvature attributesInterpretation of lineaments corresponding to subtle faults and trends can be carried out on the most-positive or most-negative curvature horizon slices as shown. The interpreted lineaments are then converted into a rose diagram which can be compared with a similar rose diagram available from image logs.

NEG

POS

Most-positive curvature

Rose Diagram

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Interpretation on curvature displays


Visualization of attributes

A stratal fault skeleton from the most-positive curvature attribute being correlated with seismic data volume in the increasing inline direction as indicated with the white arrow

Strat-cube from the most-positive curvature attribute co-rendered with coherence seen here in a 3D chair view

Strat-cube from the most-negative curvature attribute co-rendered with coherence seen here in a 3D chair view

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Thin-bed reflectivityArcis offers thin-bed reflectivity inversion using a spectral inversion technique that produces ultra-high resolution seismic data that enhances mapping. Thin-bed reflectivity removes the deleterious effects of the seismic wavelet that cause degraded resolution. Thin-bed reflectivity is performed without using well data, requires no a priori model, no interpreted horizons and no assumed reflectivity spectra.

Relative acoustic impedance derived from thin-bed reflectivity shows features that are of interest and that otherwise are not seen on the input data

Seismic

Input seismic Reflectivity convolved with bandpass wavelet

Reflectivity


Correction for spurious phase via estimation of non-minimum phase waveletDeconvolution with minimum phase wavelet assumption usually leaves the data with spurious phase. The phase correction required to remove the spurious phase is done by a simple parameterization of the underlying mixed phase wavelet, which involves estimation of an all-pass operator coefficients via cumulant matching technique. The approach involves setting up a cost function with unknown shape and using a simulated annealing algorithm for optimization.

Original data Phase corrected data

Original data. The inserted curve is the P-velocity log Phase corrected data. The inserted curve is the P-velocity log

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Rock physics analysisFor a better understanding of lithology and fluid differentiation, Arcis emphasizes the importance of rock physics analysis and integrating that with the AVO/LMR processing flow. Arcis uses an informative and straight forward approach to exhibit the elastic and petrophysical properties of reservoir rocks.

VP against VS

P-impedance against S-impedance

Lambda-Rho against Mu-Rho

VP against VP/VS

VP against Poisson’s ratio

Lambda-Rho against Lambda/Mu


AVO/LMR analysisArcis has the capability and innovativeness to accomplish AVO/LMR analysis including AVO friendly processing, QC and interpretation.

Overlay of angle information on offset gathers

Lambda-Rho

Mu-Rho

Input gathers Reconstructed gathers Difference

NEG

POS

LOW HIGH

3D Cross-plotting of Lambda-Rho, Mu-Rho and Fluid Stack. Clusters associated with gas anomalies (yellow) separated out

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Spectral decompositionSpectral decomposition allows utilization of the discrete frequency components of the seismic bandwidth to interpret and understand the subtle details of subsurface stratigraphy. Besides the traditional Fourier transform, Arcis offers the CWT (Continuous Wavelet Transform), Matching Pursuit Decomposition (MPD) and Exponential Pursuit Decomposition (EPD) methods for transformation of data to frequency domain. The latter two techniques offer more accurate analysis.

Horizon slice from a seismic volume

Horizon slice through the seismic volume and passing through the Doig sandstone

Equivalent horizon slice from merged frequency volume (with 20 Hz, 30 Hz, and 40 Hz) and using RGB with seismic

Waveform classification map generated by hierarchichal unconstrained waveform classification. Notice the higher level of facies detail that is seen on this display compared with the seismic amplitude alone, within the sandstone boundary drawn in black.

Seismic facies classificationSeismic waveforms in the broad zone of interest are categorized and related to different depositional facies. Arcis offers both unsupervised (statistical) as well as neural network (deterministic) methods for arriving at meaningful and convincing facies analysis.


Impedance inversionArcis offers several different techniques/methodologies to perform acoustic impedance inversion.

Post-stack impedance inversion • Recursiveinversion

• Model-basedinversion

• Sparse-spikeinversion

Pre-stack impedance inversion • Simultaneousinversion

• Elasticimpedance

• Extendedelasticimpedance

Segment of a section from acoustic impedance volume generated using model-based inversion

Segment of a section from acoustic impedance volume generated using simultaneous inversion

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Synthetic seismogram tie for the (left) low-angle (~10°) near-stack. The synthetic seismogram was generated by using the impedance log curve. The correlation seems to be reasonably good.

Synthetic seismogram tie for the high-angle (~30°) far-stack. The synthetic seismogram was generated by using the computed El(30°) log curve. The correlation seems to be reasonably good. Notice the weakening of the amplitudes at the location of the orange arrows.

Impedance inversionElastic impedance provides a convenient way of producing synthetic seismograms for variable angles of incidence, and combines the benefits of working with inverted data with far-angle data where the fluid information resides.

Top: Segment of the acoustic impedance section (with the overlaid AI log) shows anomalously low

values of impedance at the gas-producing zone (in yellow highlighted zone).

Below: Equivalent segment from EI (30°) section showing the anomaly as much more pronounced.

(Data courtesy: PetroNorte, Colombia)

Angle-dependent inversion


Extended elastic impedance inversion results for (top) bulk modulus, (middle) Young’s modulus, and (bottom) V-shale attributes. A good lithology and porosity variation can be interpreted considering both bulk modulus and Young’s modulus. The middle part of the V-shale zone of interest is showing high volume of shale as was expected.

Extended elastic impedance approach allows the projection of seismic amplitudes to angles of incidence outside of the recorded angles, which helps express the rock properties in terms of impedance values. A relationship between the extended elastic impedance and reservoir properties is investigated by correlation analysis (as a function of new angle, Chi) between EEI logs and available petrophysical logs such as V-shale, porosity and saturation, as well as lithology logs, such as gamma ray. Once the optimum angle Chi is determined, AVO analysis is carried out to obtain intercept and gradient attributes, and their linear combination allows the determination of the reservoir properties.

Extended elastic impedance inversion

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P-impedance obtained from post-stack inversion. The inserted black curve is the P-impedance log

P-impedance estimated with probabilistic neural network. The inserted black curve is the P-impedance log

Impedance(m/s² g/cc)

We think different. We think seismic.

Multi-attribute analysisArcis offers neural network or cubic-b spline based multi-attribute analysis. Such an analysis is beneficial if the 3D volume has a reasonably good well control and the wells are representative of the geology in a lateral sense. Application of Probabilistic Neural Network (PNN) to estimate the P-impedance volume provides more detailed information compared to the conventional model-based P-impedance inversion. As seen in the examples below, the PNN application for acoustic impedance shows better correlation with the impedance log than the conventional P-impedance inversion.


Arcis Seismic Solutions, a wholly owned subsidiary of TGS-NOPEC Geophysical

Company, offers seismic solutions to the energy industry including seismic data

processing, reservoir analysis, advanced imaging, multi-client surveys, geotechnical

services, project management, data marketing and access to an extensive data

library. Arcis offers one of the most current 2D and 3D seismic data libraries for

the Western Canadian Sedimentary Basin, including Northeast British Columbia. We

are committed to exceptional customer service, superior data quality, innovation, and

integrity; while maintaining a focus on health, safety, and environmental stewardship.

We think different. We think seismic.

2100, 250 - 5TH Street SW Calgary, Alberta, Canada T2P 0R4 403.781.1700 or 888.269.6840 [email protected] www.arcis.comPrinted in Canada

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Arcis 2013 reservoir_bochure_