AN APPLICATION OF FLUID MOBILITY ATTRIBUTE FOR PERMEABILITY PROGNOSIS WITHIN THE MIDDLE JURASSIC SEDIMENTS IN THE SOUTHERN PART OF WESTERN SIBERIA

The study area is located in the southern part of Western Siberia. The main hydrocarbon productivity in this area is related to the middle Jurassic Ju3-4 formation. The target interval is laterally changeable and characterized by weakly anisotropic sandstones with interbedded coal and shale. As a result, there are difficulties in predicting the lateral variations of the transport properties in the Ju3-4 formation. For solving this problem, the dataset of the 3D seismic and well data (core samples, well logs, and formation testing) was utilized. The core measurements of the permeability at room conditions show a weak anisotropy in orthogonal directions and a correlation with porosity. The porosity values in scale of the well log were calculated based on the relative αSP anomalies, accounting for temperature and pressure formation conditions. Permeability in the same scale was predicted based on the porosity values and Kozeny-Carman’s formula. The comparison of permeability from core samples and permeability from well logs illustrates some similarities. For prognosis of the formation permeability in a cross-well space a seismic attribute proportional to fluid mobility was calculated. The attribute is the result of first derivatives of reflection coefficient from a permeable boundary with respect to frequency. Based on the relationship between the attribute values and the average permeability of the formation in the wells, the average formation permeability map was constructed. The map is in the accordance with known production rates in the wells.