Porosity log (PHIE) data will be used for porosity modeling. The relationship between core and log porosity data indicates environmental effects on measurement technique. After depth shift of core data to match with wireline depth, core porosity is corrected for overburden pressure. Relationship between log porosity to core porosity is expected to be one to one. However most of the time due to environmental effects, relation tends to be favouring one parameter to the other one. Therefore log porosity is reconciled to be inline with core porosity.
Vertical and lateral distribution of porosity model
To improve understanding of sub-zone reservoir characteristics, the individual sub-zone average property values at well locations will be compiled in a tabular format and distribution map.
After reconciliation, the log porosity data will be scaled-up to the 3D grid and the results will be quality checked in terms of statistical parameters. The detailed sub-zonation scheme leads to almost no or minimum distortion of the data due to this process.
Detailed data analysis of porosity at the sub-zone level will be employed to capture data distribution (histogram) and spatial variation (horizontal and vertical variograms). After checking the reliability of the data analysis and by taking data distribution into account, Sequential Gaussian Simulation algorithm (SGS) will be used for porosity modeling to generate multiple equi-probable realizations that honors the predefined histogram and variogram. Number of realization is determined by statistical analysis of all realization generated. Once the cumulative mean porosity of the generated realizations is stabilized, no more realization based on seed number of SGS simulation would be generated.
Porosity Modeling Workflow
Multiple realizations can be ranked based on pore volume in oil pool or each realization can be utilized in streamline simulation to obtain the result of dynamic impact of each realization. After statistical and dynamic behaviour ranking all realizations, one of the realizations close to the average response can be selected as the Base Case porosity model for further dynamic simulation and history match.