Three-component parallel saturation model for laminated continental shale reservoirs based on petrophysical experiments and multiscale imaging techniques

Continental laminated shale reservoirs exhibit pronounced heterogeneity, multi-mineral coupled conductive pathways, and complex pore structures, which limit the accuracy of saturation estimation. In this study, a three-component parallel conductive model was established for laminated continental shale from the Jiyang Depression. Petrophysical experiments were conducted to measure the basic properties of the studied samples. X-ray computed tomography (X-CT) was used to determine the spatial distribution of mineral laminae; quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) was employed to clarify the mineralogical types and coupling relationships of the laminae; Modular Automated Processing System (MAPS) was utilized to reveal the microstructure of different mineral laminae; and field-emission environmental scanning electron microscopy (ESEM) and confocal laser scanning microscopy (CLSM) were applied to identify hydrocarbon fillings in the pore spaces of the different laminae. The results indicate that the conductive pathways in laminated continental shale consist of clay-mineral-dominated laminae, carbonate-mineral-dominated laminae, and horizontal bedding-parallel fractures, which are coupled in parallel. A three-component parallel saturation model was proposed, with model parameters determined through petrophysical experiments and multiscale imaging techniques. The model was used to calculate the oil saturation of two typical continental shale oil wells from the Jiyang Depression. The predicted results are consistent with sealed-coring analysis results. Compared to conventional saturation models, the new model improves the accuracy of oil saturation estimation. This study provides an effective oil saturation calculation method for sweet spot evaluation in continental laminated shale reservoirs.