Different Types of VSP

1Baker Atlas MER Seismic School 2003

Different types of VSP

2003

2Baker Atlas MER Seismic School 2003 2003


Zero offset VSP vertical wellUses

Surface Seismic correlation

Over pressure prediction

Multiple Identification

Wavelet Processing

Formation Velocities

Time depth curve

Identification of events

Prediction ahead of the bit

also shot as a checkshot for purely time depth information

2003

Checkshot spacing much coarser than VSP as no imaging required



Structural MappingZero offset VSP deviated wellPorosity Evaluation

Determine Anisotropy

2003

A Zero-Offset VSP corridor stack can be used to positively calibrate phase and identify multiple reflections present on a surface seismic section. Because the VSP is recorded along the depth profile of the well, the processed Zero-Offset VSP will contain only the primary reflected arrivals above the well totaldepth.

Zero-Offset VSP and Velocity Surveys provide a geophysicist the time-depth information required to map the time-domain seismic zone of interest into the depth domain. In-situ interval velocity measurements can also be used to update the estimated stacking velocities used in surface seismic data processing.



Lateral Coverage beneath well

Fault and dip identification

Zero offset VSP deviated well

Normal Incidence

2003

Vertical travel paths no refraction therefore accurate velocities



Image specific targetZero offset VSP deviated well

Normal Incidence VSP

Offset VSP

Identify edge of gas cloud

Undershoot gas chimney

Image edge of salt diapir

Rock properties

2003



ImagingZero offset VSP deviated well


Offset VSP

Walkaway VSP

Seismic attributes

Surface processing parametersShear wave analysis

Anisotropy and AVO

Surface survey design

2003



Accurate salt flank imageZero offset VSP deviated well


Offset VSP

Walkaway VSP

Salt Proximity VSP

2003

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Baker Atlas MER Seismic School 2003


High sub-surface resolutionZero offset VSP deviated well


Offset VSP

Walkaway VSP

Salt Proximity VSP

3D VSP may be acquired in a grid

2003

Provides time-depth correlation with surface seismic data

Assists in creating a high-resolution velocity model around the wellbore

Improves reservoir characterization and delineation of faults and pinchouts

Reduces operating costs and maximizes synergy with simultaneous acquisition and processing of 3-D VSP and 3-D surface seismic data

Shared velocity model, shot statics, and deconvolutionderived from surface seismic data is applicable to the VSP data

Q compensation derived from borehole VSP data improves surface seismic resolution

Allows surface seismic AVO calibration and anisotropy detectionproviding a better understanding of lithology, porosity, pore fluids, and the orientation of aligned fractures

Contributes valuable information to time-lapse seismic studies, especially when recorded with permanently installed sensors

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High sub-surface resolutionZero offset VSP deviated well


Offset VSP

Walkaway VSP

Salt Proximity VSP

3D VSP may be acquired in a spiral

2003

Spiral easier processing, faster acquisition

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Assess changes in the subsurface with time



Offset VSP

Walkaway VSP

Salt Proximity VSP

3D VSP

Time Lapse (or 4D) VSP

Monitor well depletion

Monitor enhanced recovery

2003

Seismic data from the surface or a borehole acquired at different times over the same area to assess changes in the subsurface with time, such as fluid movement or effects of secondary recovery. The data are examined for changes in attributes related to expressions of fluid content. Time-lapseseismic data can repeat 2D, 3D (which is known as 4D seismicdata), crosswell and VSP data.

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Place the drill bit on the seismic section



Offset VSP

Walkaway VSP

Salt Proximity VSP

3D VSP


Seismic While Drilling

Predict pore pressure

Predict target (hazard) depth

Optimise mud weight

Select coring and casing points

Land the well optimally in the reservoir

Identify salt proximity in real time

2003

Seismic data from the surface or a borehole acquired at different times over the same area to assess changes in the subsurface with time, such as fluid movement or effects of secondary recovery. The data are examined for changes in attributes related to expressions of fluid content. Time-lapseseismic data can repeat 2D, 3D (which is known as 4D seismicdata), crosswell and VSP data.

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Calculate velocity between wells



Offset VSP

Walkaway VSP

Salt Proximity VSP

3D VSP


Seismic While Drilling

Cross well VSP (Tomography)

High resolution image between wellsReservoir connectivity mapping

2003

Reservoir Connectivity Mapping (RCM)

Measures interwell continuity of reservoir units

Provides high resolution image to determine:

Continuity of flow/barrier units within the reservoir

Sand channels description

Natural fracture patterns

Carbonate porosity patterns

Can be used to increase primary production and improve recovery during secondary and tertiary recovery programs

RCM and Connectivity-While-Drilling (CWD) Benefits

Improves reservoir description for reservoir monitoring and management

Assists in the planning of well tests, in-fill drilling, EOR programs, horizontal wells, and completion/ recompletionprograms

Increases production through accurate reservoir delineation and compartment identification

Details reservoir heterogeneities at the reservoir level indicated with surface seismic data

Velocity Tomography

Velocity tomography uses cross-well seismic travel-times to calculate formation velocity between wells. Direct-path travel-

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Different Types of VSP

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