Analyzing the Important Parameters during Block-to-Block Interactions in Naturally Fractured Reservoirs by means of Gray Theory

This work focused on designing ۲۷ models with different characteristics using the Taguchi test design method to rank the reservoir parameters based on the degree of importance in block-to-block interaction. All parameters that influence block-to-block interaction such as rock type, physical properties of the fluids, porosity-permeability of the matrix block, fracture aperture, deviation from the vertical axis, area, and height of the matrix block have been considered. Three different values are assigned to each parameter to reflect the wide range of reservoir characteristics. Modeling was performed by using COMSOL multiphysics. For ranking the impact of parameters on block-to-block interactions, Grey relational analysis was applied. This analysis shows that fluid properties have the greatest impact on block-to-block interactions. For the following parameters, the order of influence on the degree of re-infiltration is: physical properties of the fluids > rock type > tilt angle > matrix block cross-sectional area (height*width) > fracture opening > matrix permeability-porosity. Also according to the results, a maximum of ۴۰% of the oil drained from the upper block can enter the lower block. This reveals that how re-infiltration by production delays or non-production from lower blocks creates a great challenge to production from fractured reservoirs.

Keywords:

Naturally fractured reservoirs , Gravity Drainage , Block-to-block interaction , Re-infiltration , Grey theory , Simulation