History Matching process in 3 steps - my view
This is my view about HM process. I do not have extensive experience so all comments are welcome.
Let’s assume that you have a model successfully initialized.
We run it on reservoir volume as matching parameter and notice that observed volumes cannot be produced.
In this case I will multiply reservoir permeability until volumes are produced than I will check for reservoir pressure match.
1. PRESSURE MATCH
For matching the pressure I can play with:
- Reservoir boundaries
- Aquifer size and PI
- Rock compressibility
- Reservoir permeability
- Porosity
- Res thickness
- Contacts
- Residual Oil saturation and Connate water saturation
It is important to understand what are the ranges for each parameter can vary. For example OWC can vary in a range of 50 m but Residual oil and Connate water have reliable values while SCAL data is available. Also is important to assess the impact each parameter have inside of his determined range.
2. SATURATION MATCH
In this step I will try to match WOR and GOR and I will play with:
- Vertical and horizontal permeability. It is important in case we have layers with different permeability to understand their individual contribution to flow.
- Aquifer parameters. It is important here what type of Aquifer you have (from bottom, from edge), size, strength.
- Relative permeability curves. Even if SCAL data is present if you have a heterogeneous reservoir RelPerm need to be adjusted in my opinion. Also here is important if you have a good facies model and you can create different rock types, each having his own RelPerm table.
- Contacts are important in water , gas breakthrough time
- Well completion is not too much object of changing but there are cases when data is wrong and in reality well is perforated 2-3 meters higher or lower
Could be the case that working at this point than general pressure match from point 1 will be affected, so will be a back and forth until saturation and pressure are acceptable matched.
3. BHP / PI match
The last step in my opinion will be to match well productivity index. Could be the case that you successfully matched first 2 points but your well have in reality an average drawdown of 60 bars but in your model the fluids are produces with a drawdown of 10 bars.
For solving this problem you can change
- Horizontal and vertical permeability around the well
- Well PI
- Well skin
Again changes here could affect your WOR, GOR matching and again you need to move through this iterative process.
Thank you for reading.
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