Screening can be done in two ways:
- Go through the company or country portfolio and identify the field best suited by EOR type.
- Determine which EOR type is best suited for the reservoir, crude and water properties and subsequently match the more detailed method to the field.
- In order to determine the right EOR method for a field a screening study can be done. In this study the properties of the reservoir and fluids are analyzed and matched to the available methods.
- For fields with heavier oil thermal and polymer methods are usually considered.
- For fields with lighter oil miscible and surfactants are better suited
- In the screening study it comes down what investment is the most suited for the whole system. Investments in chemicals and facilities like e.g. CO2 pipelines, compressors, water treatment plants, heaters etc. are compared to the added recovery and production. An optimum will be determined, which is not always the cheapest, but the one that adds the most net present value.
- This is the formula for screening:
Increased Production - chemical cost - facilities & wells – tax = increased revenue
- Once the EOR “family” is determined the next step is to match the more detailed method to the field. For chemical this can range from:
- Polymer flooding
- Surfactant polymer flooding
- Alkali surfactant polymer flooding
- Low salinity flooding
- For thermal the range is:
- Low pressure steam injection
- High pressure steam injection
- In situ combustion
- For miscible EOR the options are
- CO2 injection
- Gas injection