Feasibility studies

Feasibility study and petro elastic modeling (PEM) are conducted to evaluate the possibility of using inversion and AVO as a tools for predicting reservoir rock properties and saturation from seismic data, as well as for further interpretation of AVO data.

The Feasibility studies are performed using well logs for establishing the relationships between the acoustic rock properties and their reservoir properties and saturation.

Initial data:

1. Sonic and density curves (In the absence of one of the methods – synthetic curves are calculated)
2. Results of CPI
3. Calculation of elastic properties – curves VP, VS, AIMP, SIMP, lamrho, murho, PR, EI30.
4. Crossplotting and analysis of relationships

Calculation of synthetic DTS curve:

In absence of recorded DTS curve, a synthetic curve can be calculated and the quality of the calculation is assessed against empirical lithology lines using the Greenberg-Castanga palette (model)

The quality of calculated VP and VS curves is assessed by empirical palettes

Results:

Depending on the type of sediments, pairwise correlations of elastic characteristics of the section are compared and analyzed. Correlations are evaluated in order to select the most effective relationships

Example of correlations for clastic sediments

Example of relationships for carbonate-clastic sections

Relationships analysis is performed overlaying lithology, porosity and saturation data.

Example of relationship for clastic deposits

Example of relationship for carbonate-clastic section

• The possibility of saturation type separation is evaluated. Verification is carried out on crossplots overlaying the saturation data confirmed by test results.