Downhole logging (Cross well Seismic) Applications from the Oil field to Mining

* Mark of Schlumberger

Shafiq Muhammad Borehole Seismic Domain Champion Australia, New Zealand & PNG

Agenda

• Introduction

• Acquisition

• Case Studies

Well Scale

Crosswell measurements target the reservoir

0.001 0.01 0.1 1 10 100 1,000 10,000 100,000

Depth of Investigation (m)

0.01

0.1

1

10

100

1000

Ve

rtic

al R

eso

luti

on

(m

)

Basin Scale

Reservoir Scale

Resolution scales in reservoir interpretation

After Harris et al. (1995)

Surface Crosswell EM

Logs Core

Increasing vertical resolution

Crosswell Seismic

Receivers Transmitters

w a t e r

n s

After Ed Stoessel / BP

100 m

Surface Seismic

Crosswell Seismic

opseal

OilNonpay

Format ion

eawater

Perforat io

opseal

OilNonpay

Format ion

eawater

Perforat io

Imaging seismic between wells

Surface Seismic VSP Xwell Seismic

5-120Hz 5-200Hz 30-800Hz (clamped)

100-2000Hz (piezo electric)

Typical Source Frequency Ranges

100 m

Imaging between wells

• High-resolution reservoir characterization

• Development planning

• 4D monitoring

- IOR/EOR

CSG Applications

Crosswell seismic solutions

Reflectivity Velocity – P&S

Velocity Difference Attenuation

Agenda

• Introduction

• Acquisition

• Case Studies

Wireline deployed single-component or 3C Multi-Level Receiver Array

Wireline deployed fluid-coupled or

magnetically clamped

seismic source

Receiver Array Stationed at Position of Deepest Zone

Level Spacing

2.5, 5 or 10 ft

One profile for per source position (profile)

Crosswell seismic acquisition

Receiver Array Moved 50 or 100 ft

Resolution is dependent on: - Frequency - Formation attenuation - Interwell distance

Acquisition considerations

Well Casing & Separation

Transmitter Well Receiver Well Max Spacing*

Piezo Source Hydrophones/3C 1000m

Any casing Any casing

Clamped Source Hydrophones/3C 2500m

Steel or Magnetic Cr Any

* The exact well separation achievable is obtained from pre-survey modelling

Side View

Well Geometries

Agenda

• Introduction

• Acquisition

• Case Studies

Final Crosswell Reflection Image Enlargement

4 – 5 ft. Coal

Seam

High Resolution Imaging of coal seams Case Study

Conclusions

• Allows operators to drill and target the seams with more accuracy than is

possible with any other technique

• Strengthens reservoir understanding by integrating with other seismic

measurements and frac monitoring (HFM)

• Allows a better understanding of often complex interbeded coal / shale

sequences so the cleanest, highest-producing zones can be targeted

• Provides a detailed view of the natural faulted structures within the coal

• Time lapse crosswell seismic monitoring using velocity clearly indicates

gas/fluid effects from methane extraction

• Xwell Seismic can be used in mining industry too for similar applications.

Thank You &

Questions