Purpose
of Geological Models
The main reason for building geological models is to better understand
the reservoir and make predictions as to further activity in the field.
A geological model has the advantage that many data types can be incorporated.
This leads to a model that attempts to fit all the data and various theories
can be tested. The 3-D viewing in general leads to improved visualisation,
but maps and cross sections should also be used to check various stages
of the modelling process. The analogy can be made with field-work in
that even though the outcrops are in 3-D, the geologist makes maps and
cross sections for better understanding and illustration.
Objectives
Before embarking on a geological modelling study, it is important to establish the objective with all parties. This will then be linked with the data that needs to be made available and the time that will be needed to complete the study.
- Hydrocarbons in place (STOIIP, GIIP)
- Reservoir simulation – history matching
- Identify areas of remaining hydrocarbons (infill drilling)
- Field Development Planning
- Well planning
- Following drilling progress and updating the model
The study is NOT
- A mechanical exercise in a favourite software package
- Just a 2-D mapping project
- Just a question of averaging the well data for each property
- An exercise that is “finalised” and then handed over to the reservoir engineer
- A lengthy study to prove a particular persons geological theory!
Conclusions
Geological Modelling and associated software has advanced considerably in the last 15 years. It has come out of the major oil company research centres and more into everyday use in companies of all sizes and for relatively small projects. However the underlying geological considerations and uncertainties in the well data still need to be studied carefully before valid results can be obtained.
