FRACTURED RESERVOIR IMAGING SOLUTIONS

12300 Parc Crest Drive Stafford, TX 77477 USA

Tel + 1 281 933 3339 Fax + 1 281 879 3626

www.i-o.com/fullwave

10/2005

SALES

United StatesTel + 1 281 933 3339Fax + 1 281 552 3150

CanadaTel + 1 403 213 8769Fax + 1 403 620 6333

Latin AmericaTel + 57 310 576 2579

Europe and AfricaTel + 44 1 483 277 644Fax + 44 1 483 277 655

Middle East

EgyptTel + 20 127 303 224

BahrainTel + 973 17 581 376Fax + 973 17 581 375

China and Pacific RimTel + 86 10 8453 4350Fax + 86 10 8453 4351

Russia and CISTel + 7 095 937 7741Fax + 7 095 937 6782

AXIS Imaging Division

225 East 16th Avenue Denver, CO 80203

Tel + 1 303 318 7780 Fax + 1 303 444 8632

Overview

While naturally-fractured reservoirs are becoming increasingly important contributors to theworldwide hydrocarbon reserve and production base, they are notoriously difficult to image.New seismic imaging technologies have been developed and are now available to help geoscientists map fracture patterns and associated reservoir permeability changes. As a result,E&P operators are now better able to target highly productive zones within these heterogeneous reservoirs.

As a leading technology-focused seismic solutions company, I/O possesses the technologytoolkit and application expertise to make the most challenging fractured reservoir imagingprojects successful.

I/Os end-to-end suite of products and services enables geoscientists to: Design surveys customized for fractured reservoir imaging, where long offsets, wide

azimuth geometries and high sensor densities are often needed to detect and resolve fracture patterns and connectivity

Measure seismic response with high fidelity and accuracy using VectorSeis full-wave, 3C sensors, especially to assess attributes unique to fractured reservoirs such as fast and slowinterval velocities, azimuthally-varying velocities and AVO, and shear wave splitting intensity and orientation

Improve image quality and resolution by accounting for azimuthal velocity variations withAZIM, I/Os suite of anisotropic velocity imaging applications

Use seismically-derived fractured reservoir parameters and subsurface information to calibrate and generate Discrete Fracture Network (DFN) reservoir models that guide drilling decisions and field development planning

As a proven leader in developing cutting-edge acquisition hardware and software, as well asin offering services for seismic survey design and advanced imaging, I/O is becoming a clearfirst-choice provider for E&P operators whose asset portfolios include fractured reservoirs.

Fractured Reservoir Imaging Challenges

Naturally-fractured reservoirs are an important component of the global hydrocarbon reserveand production base. In many parts of the world, including the Middle East and Mexico, fractured reservoirs account for the bulk of production. In other areas, such as the Rockies ofNorth America, low permeability formations that were once considered unconventionalhydrocarbon resources are now quickly becoming mainstream.

A key part of fractured reservoir characterization is making high-quality measurements ofanisotropy, which indirectly indicates fracture orientation and intensity. In a vertically fractured zone, AVO response will vary with azimuth. The largest variation will occur between AVO responses parallel and perpendicular to the dominant fracturing direction.

In order to measure this anisotropy and properly characterize fractured reservoirs, geophysicistsmust ensure the following: Surveys are designed with long offsets, wide azimuths, and high station density to ensure

the subsurface is adequately sampled in all directions Seismic data is recorded using high-fidelity, 3C sensors that capture broadband P-wave

and S-wave data (especially at lower frequencies) Processing workflows account for P-wave Vfast and Vslow magnitudes and directions,

shear wave splitting, and azimuthally-varying AVO All available seismic, engineering, and geologic data is integrated to relate seismic

attributes to reservoir fracturing, and to tie reservoir fracture models to actual production

F R A C T U R E D R E S E R V O I R I M A G I N G S O L U T I O N S

About I/O

I/O is a leading, technology-focused seismic

solutions company. The company provides

cutting-edge seismic acquisition equipment,

software, and planning and seismic processing

services to the global oil and gas industry. I/Os

technologies are applied in both land and

marine environments, in traditional 2D and

3D surveys, and in rapidly growing areas like

time-lapse (4D) reservoir monitoring and

full-wave imaging.

I/Os award-winning imaging technologies

fully integrate seismic acquisition equipment,

software and related survey design, data

management and seismic processing services.

They have been used successfully worldwide

in the hunt for oil and gas reserves. From

vibrators, energy source controllers

and sensors to acquisition recording

systems and software, our technologies

enable oil & gas companies to efficiently

acquire the highest quality seismic images

and help acquisition contractors achieve

significant productivity benefits.

I/O full-wave imaging applications throughout the world

Full-Wave Imaging

Fractured reservoirs are becoming one of the key proving grounds for the emerging technologies of the Digital, Full-wave seismic era. Unlike conventional seismic in which onlythe vertical component of particle motion is measured, full-wave acquisition involves: Faithfully recording complete ground motion in three dimensions by recording the

full seismic wavefield, including source-generated noise Recording the broadest bandwidth of frequencies that the Earth will return Accurately measuring anisotropy (including amplitude and velocity variations) for both

P-waves and S-waves Obtaining an unaliased spatial sampling of the imaging target(s) for a given dip,

frequency and velocity

VectorSeis 3C, single-point receivers are unsurpassed in their ability to measure groundmotion in 3D and record the full seismic wavefield with the highest vector fidelity in the market. Unlike receiver arrays, VectorSeis sensors more accurately sample and measure thefull seismic response. As a single-point receiver, VectorSeis does not suffer from intra-arraystatics. With only one sensor at each receiver station, VectorSeis delivers a superior responseto seismic signals compared to geophone arrays and records the broadest frequency bandwidth that the Earth will return. When deployed in wide-azimuth, long-offset configurations, VectorSeis acquires data with improved utility, including better characterizedseismic attributes for anisotropy and AVO analyses.

Full-wave imaging is about more than just the sensor. It is also about how surveys are designed and how the data is processed. Measuring the full seismic wavefield and deriving those seismic properties indicative of fracturing requires innovative processing techniques.

GX Technology, an I/O subsidiary, provides advanced processing for full-wave data, includinganisotropy attribute volumes. I/O's award-winning AZIM suite of velocity processing techniques generates higher-order velocity analyses quickly and with high degrees of accuracy. AZIM rigorously identifies and corrects for azimuthally-varying velocities, deliveringbroadband, high resolution seismic images and anisotropy attributes required for characterizing reservoir fracture density and orientation.

I/Os Discrete Fracture Network (DFN) modeling service builds off the foundations of AZIM,enabling geoscientists to seamlessly integrate seismic, engineering, and geologic data tomodel the connectivity of naturally-fractured reservoirs, match seismic responses to actualwell production profiles and optimize future drilling and field development programs.

Solutions Overview

Combinations of innovative field acquisition technologies and processing techniques arenecessary to solve fractured reservoir imaging challenges. I/O offers the broadest range oftechnologies and services for the most complex imaging requirements: Advanced survey design and planning services for wide-azimuth, 3C (multicomponent)

acquisition Award-winning, full-wave VectorSeis sensors Industry-recognized data processing techniques (like AZIM) that address complex imaging

challenges unique to fractured reservoirs Services and software for reconciling seismic data and attributes with reservoir,

production, and geological information to generate fracture properties for reservoir models

VectorSeis accelerometers and circuit

boards, showing two of three orthogonally-

mounted MEMS accelerometers, located at

the receiver base for noise isolation

VectorSeis single-point receiver, ideal for

accurate anisotropy measurements

Core, Log, Image Log and Production Data Evaluation Services

I/O experts routinely assist geoscientists in evaluating log, core and production information tooptimize seismic surveys for fractured reservoir imaging. Existing subsurface data is often critical for designing seismic surveys and developing fractured reservoir models that linkacquired seismic data to reservoir production patterns.

Statistics on open or conductive fracture orientations and intensities are used to characterizethe type of fracture system and the physical processes that generated the fractures. Imagelogs and cores provide the initial data, and an iterative combination of local Discrete FractureNetwork (DFN) modeling and statistics are used to quantify the change in fracturing from onewell to the next. Deviations in well orientation can be corrected for, while calibrationbetween fracturing and production can be assessed. Interpretation of production logs specific to fractured reservoir performance is used to develop a conceptual and quantitativemodel of the reservoir plumbing. The relative influence of the matrix is also examined.Finally, controls on reservoir performance can be calibrated to seismic attributes to predictwell performance ahead of the drill bit.

Survey Design and Planning Services

I/O can help design your fractured reservoir surveys to take advantage of the latest advancesin full-wave acquisition and processing technology. Our design experts, using GMGs MESA

survey design and modeling software, can help design tailored seismic surveys that improve the accuracy of anisotropy measurements and improve fractured reservoir characterization.

Full-wave imaging techniques allow surveys to be designed for image quality and accurateanisotropy measurements rather than noise suppression. Receiver arrays that suffer fromdirectional bias are no longer required to mechanically filter ground roll and side-scatterednoise in the field. Rather, coherent noise filtering can now be done in processing.

The deployment of full-wave, single-point receivers ensures that directional bias does notaffect the recorded seismic signal. Depending on your imaging objectives, significant reductions in the number of source and receiver points are possible when designing a surveyfor image quality rather than noise suppression.

High-quality, full-wave imaging for fractured reservoirs requires full azimuthal coverage and long offsets to capture anisotropy, as well as AVO data (particularly azimuthally-varying AVO), azimuthally varying attenuation, and sufficient receiver density to avoid spatial aliasing imaging objectives. I/Os survey design and planning experts are prepared toassist in designing P-wave, C-wave and S-wave surveys that cost-effectively fulfill these goals.

Sensors

Fractured reservoir imaging requires that acquired data be of the highest bandwidth and vector fidelity, attributes not easily addressed with geophone arrays. High-fidelity VectorSeissensors record the broadest bandwidth data of any seismic receiver on the market and areunsurpassed in their ability to capture seismic measurements that provide clues to fracturing.Because they acquire seismic data without any directional bias, they are particularly useful forhigh-quality anisotropy measurements. VectorSeis sensors more accurately sample all seismicenergy, including azimuthal velocity and AVO variations. Since VectorSeis is a single-pointreceiver, it does not suffer from intra-array statics problems and delivers the broadest bandwidth data, from 1 - 2 Hz to the highest frequencies the Earth will return.

In every VectorSeis sensor, three MEMS accelerometers are mounted on a precision-machinedaluminum cube for the highest vector fidelity acquisition. VectorSeis is designed to capturethe full richness of both P-wave and S-wave motions along with their anisotropy characteristics.VectorSeis accelerometers are located at the base of the receiver for isolation from wind andother sources of surface noise that can contaminate seismic signals.

Complex azimuthally-dependent frequency

attenuation patterns from a six-geophone

array

Simple isotropic response of single-

point receiver

Seismic Data Processing Techniques

Wide-azimuth, long-offset surveys acquired with VectorSeis 3C sensors paint a more holistic,accurate and higher utility picture of the subsurface. Because VectorSeis records the completeseismic wavefield, high-quality AVO measurements are preserved (even for long offsets).

Taking full advantage of the acquired seismic data for fractured reservoir imaging requires aseries of special processing techniques and considerations: Applying vector filtering techniques to attenuate ground roll and side-scattered noise and

enhance the bandwidth of the recorded P-wave energy Isolating and removing S-wave and C-wave energy from P-wave energy to mitigate mode

contamination issues common in hard-surface areas Rigorously handling velocity and AVO anisotropy effects, while taking advantage of

recorded P-wave energy from the horizontal components of long-offset VectorSeis sensors Generating attribute volumes and measurements such as azimuthal AVO and velocities,

fast and slow directions for both P-waves and S-waves, and shear wave splitting characteristics for fractured reservoir intervals

Separating overburden anisotropy effects from reservoir anisotropy effects

The conventional assumption of vertically emergent P-wave and S-wave rays has proven to beincorrect, especially in areas where shallow, high velocity zones can significantly refract seismic energy. Resulting problems include contamination of recorded P-wave energy with S-wave energy, and vice versa. Additionally, amplitude measurements and AVO analyses usinglong offsets are less accurate because the emergent P-waves are not vertical. If conventionalgeophone arrays are used, the non-vertical component of P-wave energy will not be recorded.

Full-wave acquisition techniques record the full seismic wavefield, allowing non-verticallyemergent P-wave and S-wave energy to be isolated and characterized. Mode contaminationcan also be addressed with single-point, 3C sensors, while AVO measurements should improveif proper vector processing techniques are applied.

Wide-azimuth survey designs and VectorSeis single-point receivers enable more accuratemeasurement and processing for anisotropy. Velocities must be analyzed in offset andazimuth, but with a spatial density on scale with the sampled bin grid size. This can beachieved in a timely manner only by using sophisticated techniques that account forazimuthally-varying velocities.

The AZIM processing technique was designed with this consideration in mind. AZIM yieldsextremely dense, azimuthal velocity volumes that can be used to correct for azimuthal velocity variations in seismic data. In addition to clearer seismic images, these analyses produce densely-sampled velocity volumes that can be treated as data attributes. From thesevolumes, users can extract directional information, interval velocities, gradients and more, all providing clues to the subsurface. These new insights have proven extremely helpful inunderstanding the subsurface in a variety of areas, including the U.S. mid-continent andonshore North Africa.

Reconciling Seismic Data and Attributes with Subsurface Fractured Reservoir Information

Open fractures change the response of rock in the subsurface as a function of the azimuth ofthe ray path between source and receiver. These effects are seen as changes in the azimuthalvelocity (interval NMO) and amplitude (azimuthal AVO). Depending upon the reservoir architecture and the acquisition geometry, both fracture orientation and intensity may be calibrated to the anisotropic attributes. Quantitative calibration of the seismic anisotropy toother sources of fracture information, such as core, image log and well production data, isthen possible.

Subsurface data coverage for conven-

tional shoebox (top) and wide

azimuth (bottom) survey designs

Seismically-Guided Discrete Fracture Network (DFN) Modeling

Seismic Discrete Fracture Network (DFN) models can be constructed to integrate geologic,geophysical and production attributes related to fracturing. These models can then be usedto populate a reservoir simulation model with fracture properties; in essence, extending thehard fracture information at the well locations using soft fracture information derived fromseismic attributes between the wells.

The DFN model allows the interpreter to validate both the conceptual model of how andwhere the fracturing occurs, as well as the consequences of fracturing on the reservoir architecture. DFN will predict both volumes and rates and allow one to qualitatively calibrateseismic anisotropy to image logs, core and production data. Models can then be used in a go-forward mode to quantify risk and estimate success rates for multiple drilling scenarios.

Conclusions

Fractured reservoirs are a key component of most oil & gas companies upstream asset portfolios. However, naturally-fractured reservoirs are challenging to image. Fortunately,advanced seismic technologies and techniques are emerging that will afford asset ownerswith higher quality, higher utility measurements of fractured reservoirs. When these technologies are accompanied by innovative approaches to seismic survey design, data processing, and reservoir modeling, E&P firms are better able to characterize these heterogeneous reservoirs.

With better characterization comes reduced drilling risk and more finely tuned field development and investment programs. When the imaging challenges are at their mostextreme, as they are in fractured reservoir imaging, I/O is the technology-focused seismic solutions company that you can count on.

Measured seismic anisotropy

DFN model

Fractured reservoirs form DFN model

Overview

While naturally-fractured reservoirs are becoming increasingly important contributors to theworldwide hydrocarbon reserve and production base, they are notoriously difficult to image.New seismic imaging technologies have been developed and are now available to help geoscientists map fracture patterns and associated reservoir permeability changes. As a result,E&P operators are now better able to target highly productive zones within these heterogeneous reservoirs.

As a leading technology-focused seismic solutions company, I/O possesses the technologytoolkit and application expertise to make the most challenging fractured reservoir imagingprojects successful.

I/Os end-to-end suite of products and services enables geoscientists to: Design surveys customized for fractured reservoir imaging, where long offsets, wide

azimuth geometries and high sensor densities are often needed to detect and resolve fracture patterns and connectivity

Measure seismic response with high fidelity and accuracy using VectorSeis full-wave, 3C sensors, especially to assess attributes unique to fractured reservoirs such as fast and slowinterval velocities, azimuthally-varying velocities and AVO, and shear wave splitting intensity and orientation

Improve image quality and resolution by accounting for azimuthal velocity variations withAZIM, I/Os suite of anisotropic velocity imaging applications

Use seismically-derived fractured reservoir parameters and subsurface information to calibrate and generate Discrete Fracture Network (DFN) reservoir models that guide drilling decisions and field development planning

As a proven leader in developing cutting-edge acquisition hardware and software, as well asin offering services for seismic survey design and advanced imaging, I/O is becoming a clearfirst-choice provider for E&P operators whose asset portfolios include fractured reservoirs.

Fractured Reservoir Imaging Challenges

Naturally-fractured reservoirs are an important component of the global hydrocarbon reserveand production base. In many parts of the world, including the Middle East and Mexico, fractured reservoirs account for the bulk of production. In other areas, such as the Rockies ofNorth America, low permeability formations that were once considered unconventionalhydrocarbon resources are now quickly becoming mainstream.

A key part of fractured reservoir characterization is making high-quality measurements ofanisotropy, which indirectly indicates fracture orientation and intensity. In a vertically fractured zone, AVO response will vary with azimuth. The largest variation will occur between AVO responses parallel and perpendicular to the dominant fracturing direction.

In order to measure this anisotropy and properly characterize fractured reservoirs, geophysicistsmust ensure the following: Surveys are designed with long offsets, wide azimuths, and high station density to ensure

the subsurface is adequately sampled in all directions Seismic data is recorded using high-fidelity, 3C sensors that capture broadband P-wave

and S-wave data (especially at lower frequencies) Processing workflows account for P-wave Vfast and Vslow magnitudes and directions,

shear wave splitting, and azimuthally-varying AVO All available seismic, engineering, and geologic data is integrated to relate seismic

attributes to reservoir fracturing, and to tie reservoir fracture models to actual production

F R A C T U R E D R E S E R V O I R I M A G I N G S O L U T I O N S

About I/O

I/O is a leading, technology-focused seismic

solutions company. The company provides

cutting-edge seismic acquisition equipment,

software, and planning and seismic processing

services to the global oil and gas industry. I/Os

technologies are applied in both land and

marine environments, in traditional 2D and

3D surveys, and in rapidly growing areas like

time-lapse (4D) reservoir monitoring and

full-wave imaging.

I/Os award-winning imaging technologies

fully integrate seismic acquisition equipment,

software and related survey design, data

management and seismic processing services.

They have been used successfully worldwide

in the hunt for oil and gas reserves. From

vibrators, energy source controllers

and sensors to acquisition recording

systems and software, our technologies

enable oil & gas companies to efficiently

acquire the highest quality seismic images

and help acquisition contractors achieve

significant productivity benefits.

I/O full-wave imaging applications throughout the world

FRACTURED RESERVOIR IMAGING SOLUTIONS

12300 Parc Crest Drive Stafford, TX 77477 USA

Tel + 1 281 933 3339 Fax + 1 281 879 3626

www.i-o.com/fullwave

10/2005

SALES

United StatesTel + 1 281 933 3339Fax + 1 281 552 3150

CanadaTel + 1 403 213 8769Fax + 1 403 620 6333

Latin AmericaTel + 57 310 576 2579

Europe and AfricaTel + 44 1 483 277 644Fax + 44 1 483 277 655

Middle East

EgyptTel + 20 127 303 224

BahrainTel + 973 17 581 376Fax + 973 17 581 375

China and Pacific RimTel + 86 10 8453 4350Fax + 86 10 8453 4351

Russia and CISTel + 7 095 937 7741Fax + 7 095 937 6782

AXIS Imaging Division

225 East 16th Avenue Denver, CO 80203

Tel + 1 303 318 7780 Fax + 1 303 444 8632