Designer Seismic VSPDesigner Seismic VSP

Ernie Majer (LBNL)J. Queen ( Hi –Q Geophysics)

T. Dalely (LBNL) Roy Long ( DOE)

AcknowlegementsAcknowlegements

Whiting Oil and Gas Company

U.S. DOE Oil and Gas Program

Goal of Microhole Seismic MethodsGoal of Microhole Seismic Methods

Active Seismic Define fine scale structure and lithology controlling fluid flow and content

Fracture flow versus matrix flow Fault locations, bedding, pinch outs, compartment size and geometry,

etc. Discriminate fluid type and content in near and long term

Oil/water/gas interface CO2, steam, water drive efficiency, etc

Cost effective!!!

Passive Seismic Low cost means to monitor dynamics of reservoir as fluid is produced and/or

injected Hydrofracture creation Interaction in the long and short term of natural fractures with induced

fractures Effect and interaction of reservoir properties with changing stress

Provide validation of reservoir manipulation

COCO22 Project Results at Teapot Dome, WY Project Results at Teapot Dome, WY Using VSP Microhole TechnologyUsing VSP Microhole Technology

Note: Modified from Kinder Morgan CO2 LP Company

Weathered Zone

Deep Targets

(Ref. October, 2006 Issue of SEG’s Leading Edge – “Cost-effective imaging ofCO2 injection with borehole seismic methods”: http://tle.geoscienceworld.org/

• Changes the way we explore for oil and gas

• Changes the way we monitor EOR projects

Micro-Electromechanical Systems (MEMS)

Microhole Technologies for ImagingMicrohole Technologies for Imaging

Field DeployedMEMS Geophone Array

Demonstrate Microhole/Downward Looking VSPDemonstrate Microhole/Downward Looking VSPLANL/LBNLLANL/LBNLObjective

Demonstrate improved highresolution active seismic(uses man-made sound source)Demonstrate cost effectivenessof shallow, low cost, VSPinstrument boreholes for continuous monitoring withactive and passive seismic(uses naturally occurringsound source)

AccomplishmentsShallow Microhole VSP “sees” up to 4 times (or more) shallow hole depthUp to three times better resolution than VSP in conventionally drilled boreholes (much better signal to noise ratio)

BenefitsPermits use of microholes for low cost, rapid VSP deployment because sensors do not need to be placed at reservoir level High resolution seismic surveys can be faster and much cheaper with permanently installed shallow, instrument boreholesCost effective, permanent VSP boreholes could revolutionize complex reservoir characterization and long term EOR monitoring

RMOTC VSP compared to Surface SeismicRMOTC VSP compared to Surface Seismic

Approximate hole depth

2nd wall creek

Lakota

Red peak

Tensleep

Shannon

1st wall creek

6000 feet6000 feet

Zero Offset Microwell VSPZero Offset Microwell VSP

Whiting VSP/MonitoringWhiting VSP/Monitoring Purpose Apply Microhole VSP to focus on areas of

uncertainty Examine litholgy and heterogenety Valdate location of features controlling CO2 migration

Linements Continuity of lithology

Detect changes in seismic due to CO2 ( time lapse)

Approach Apply VSP in at least three microholes (ended up

with 5) Apply passive monitoring to determine effect of

fluids on stress

Logistics No surface lines necessary All recording performed at VSP Well

Noise Versus Noise Versus DepthDepth

for Microholefor Microhole

Noise Level at 500 feet Depth Is 60 dB Less Than Surface Noise

Wickett Field

CO2 Start-Up Area (Phase 1),Section 19 of GWO Lease

COCO22 Sequestration Project Sequestration Project

Inject CO2

along 2 lines

Drive Oil to wells between lines

Monitor CO2

injection with Time Lapse Microhole 3D seismic survey

Geophone Installation

Completed Microwell

Geophone, 1” OD

Acquisition DesignAcquisition DesignReflection Point DensityReflection Point Density

(assumes uniform velocity)(assumes uniform velocity)

Acquisition DesignAcquisition DesignReflection PointsReflection Points(assumes uniform velocity)(assumes uniform velocity)

Actual Field AcquisitionActual Field Acquisition

Two Surveys after CO Two Surveys after CO 22 Injection was Started - Injection was Started -

SummarySummaryFebruary 2007 Vibroseis Source

10 – 100 Hz 5 sweeps 2 ms sample rate

165 Shot Points 5 Wells 825 VSP's ~200,000 traces

August 2007

Vibroseis Source 10 – 100 Hz 5 sweeps 2 ms sample rate

231 Shot Points 5 Wells 1,155 VSP's ~275,000 traces

Frequency ContentFrequency Content

FFT Results for 5 Depths Between 313' & 380'SP 710 to MW_04

2-D Processing2-D ProcessingLine 7 Shot Points 701 – 713 Wells 1 and 4Line 5 Shot Points 501 – 535 Wells 3, 4, 5, &6

Processing for Time Lapse Processing for Time Lapse Reflection Amplitude ChangeReflection Amplitude Change

Apply static shifts from explosive shot monitor. Edit noisy traces, sort by depth, etc.

Use F-K filters to remove downgoing and enhance upgoing energy.

Obtain reflection section for pre and post data

For time-lapse change: normalize reflection amplitude using a shallower reflector above the Frio.

Calculate change in reflection amplitude

Line 7 Time Lapse AnalysisLine 7 Time Lapse Analysis

Compare Old and New VSP Migrations

Pick Horizon at ~ -570' on Both Data Sets Bright event above reservoir interval

Flatten Both Data Sets to Common Depth

Normalize Old Amplitudes Calculate RMS amp. for picked event on both data

sets

Multiply entire Old data set by ratio of RMSnew/RMSold for picked event

Difference the Old and New Data

Approach:

Data After Flattening to Common Data After Flattening to Common DepthDepth

OLD NEW

Yates Topsfrom WellGWO-156

FlattenedDepth

Difference Plot of Old – New Difference Plot of Old – New After Flatten and NormalizeAfter Flatten and Normalize

Yates Topsfrom WellGWO-156

Largest Differences Show Up Here

Line 5 Time Lapse AnalysisLine 5 Time Lapse Analysis

Compare Old and New VSP Migrations

Pick Horizon at ~ -410' on Both Data Sets Bright event above reservoir interval

Flatten Both Data Sets to Common Depth

Normalize Old Amplitudes Calculate RMS amp. for picked event on both data

sets

Multiply entire Old data set by ratio of RMSnew/RMSold for picked event

Difference the Old and New Data

Approach:

Comparison of Old and New Line Comparison of Old and New Line 5 VSP Depth Migration Results5 VSP Depth Migration Results

OLD NEW

ReservoirInterval

Data After Normalizing Old Data After Normalizing Old AmplitudesAmplitudes

OLD

NEW

Yates Topsfrom WellGWO-156

Yates Topsfrom WellGWO-156

FlattenedHorizon

FlattenedHorizon

Difference Plot of Old – New Difference Plot of Old – New After Flatten and NormalizeAfter Flatten and Normalize

Yates Topsfrom WellGWO-156

Future WorkFuture WorkDevelop Microhole drilling technology

Refine and develop processing technology (time lapse acquisition)

Improve sensors and acquisition capability

Next Generation Sensors

Wide Bband Width: DC – Kilohertz

High Sensitivity: 10X Current 2008 Technology

Low Cost