An Innovative Approach to Estimate and Predict High Resolution Permeability in Non-Cored Wells of Laminated Clastic Reservoirs of Black Sea, Turkey

Abstract The Western Black Sea's deep-water gas reservoirs are made up of intricate, highly laminated sand and shale sequences. To date, capturing intrinsic or individual bed features, especially permeability, in such highly laminated sands using well logs has remained a significant challenge. To tackle this challenge in such reservoirs, a novel permeability modeling approach was adopted in this study. Above the gas water contact, the resistivity of rock is a function of water saturation and rock quality in terms of porosity and permeability. However, the standard resistivity log resolution of approximately 2 ft is insufficient to capture the properties of thin beds. Therefore, in order to obtain a high-resolution quantitative indicator of permeability variation, alpha processing was applied to image log derived Synthetic Resistivity (SRES) by using Standard Induction Resistivity. And, it is observed that there is a relationship between alpha-processed SRES and profile permeability. Once all the data had been quality-controlled, a correlation between calibrated profile permeability and alpha-processed SRES was established for different rock types. As a result, KH predictions derived from the proposed permeability model matched closely with the permeability-thickness (KH) measurements from well tests, particularly in areas with significant facies changes. While conventional logs can address layered reservoirs volumetrically, they are inadequate for representing the thickness of the beds layer by layer. In the study area, a new high-resolution methodology was developed to calculate porosity and saturation at a similar resolution to image logs by statistically integrating core data together with image logs, including routine core analysis (RCA) and special core analysis (SCAL), without the need for traditional log deconvolution. However, the current study introduces a new high-resolution permeability modeling to predict permeability log similar to image resolution (~0.2 inch) where permeability varies significantly layer by layer depending on grain size differences, even within the same facies. The new technique, termed as Resistivity Alpha Core Method (RAC), was designed to estimate permeability in cored wells and propagate the results to non-cored wells in laminated clastic reservoirs. This technique effectively captures and predicts KH variations in reservoir intervals, even where KH differs widely across similar intervals in different wells. The method reduces uncertainty in permeability modeling and serves as a valuable tool for well production forecasts in fields with similar depositional settings.