Reservoir Eng 7: Geophysics for reservoir characterization

Reference
WCWO-E

Objectives

The oil and gas reservoir characterisation is part of the global process of Reservoir Management. This consists on the application of all industrial technologies and field practice to efficiently develop the hydrocarbons and maximise the return on investment.

Seismic is one important technique that participates to a better reservoir knowledge.

While wells are discrete locations in an oil and gas field, seismic is the only technique that gives a continuous picture of the reservoir characteristic.

The reservoir is complex and invisible. Seismic project dedicated to the reservoir should be well planned and executed as reservoir characterisation needs the use of different seismic techniques. These techniques start with structural interpretation going through stratigraphy interpretation, then acoustic and elastic inversion, amplitude versus offset (AVO) study, attribute study and more advanced techniques such as un-supervised and supervised classification of the reservoir data and artificial neural network (ANN).

Understanding the long-term behaviour of the reservoir, 4-D seismic should be applied.

The present course is an overview of all these techniques that allows petroleum engineers to understand how the seismic data can help them in their day by day work. Each seismic study is presented according to the specific reservoir parameters that is be able to define and clarify. Participants will also familiarise themselves with the terminology of these techniques to be able to have constructive discussions with the other members of the exploration and production team.  

Different types of interpretation are presented starting from prospect generation going through facies and stratigraphy interpretation and finally more advanced techniques are discussed with emphasis on reservoir parameters determination. Each new concept is followed by some exercises. About half the time will be dedicated to practical and manual exercises. This gives attendees the possibility to manipulate many different seismic lines to understand the added value of seismic techniques in their future activities.

Content

 Day 1

Introduction to reservoir characterisation

The reservoir characterisation within the reservoir management process.

Different components of hydrocarbon reservoir.

Why we need better reservoir knowledge?

The reservoir as seen in seismic data.

Tools for reservoir characterisation.

Fundamentals laws in seismic reflection technique

Propagation of seismic waves in stratified medium. Equations of waves in a shot point.

The concept of seismic acquisition

Exercises

Shot point analysis.

The concept of Common Mid-Point (CMP)

The concept of fold of coverage.

Day 2

02.1     From Shotpoint to seismic line

General expression of a seismic trace

From shotpoint domain to CMP domain.

Recovery of the reflectivity

Noise reduction

Deconvolution

NMO correction and Stacking

Migration

02.2      Exercises

02.3     Reservoir in seismic structural interpretation

Calibration of seismic data with well data

Principle of structural interpretation

Selection of marker and polarity

Posting and contouring

Fault in extensional regime

Fault in compressional regime

Posting and contouring

Mapping

Reservoir parameters .

 Day 3

         03.1    Exercises

Interpretation of seismic lines

Contouring

Parameters of the reservoir

         03.1     Reservoir in stratigraphy interpretation

Principles of stratigraphy interpretation

Shoreline migration

Sequence boundary

Sequence stratigraphy

Boundary relationships

Internal configurations

Progradation

Reservoir facies and parameters

Day 4

     04.1    Exercises

Internal fill and configurations

Progradation

Facies and other reservoir parameters

    04.2    4-D Technique

What is 4-D seismic and when is needed

Preparing 4-D project

4-D attributes

    04.3     AVO and reservoir classification

Principles of AVO (Amplitude Versus Offset)

Reflection coefficients and offsets

AVO attributes

Reservoir classification

Exercises