Influence of Formation Lower Limit on the Physical Properties of Shrinkage Pores in a Tight Sandy Conglomerate Sample

For shrinkable pore-developed sandy conglomerate formation, the identification of the formation lower limit is of great significance in characterizing the physical properties. In this paper, a 3D gray image of a shrinkage pore-developed sandy conglomerate sample is obtained with micro-CT scanning, the maximum class spacing algorithm is used for binarization segmentation to construct the 3D shrinkage pore digital rock, and the corresponding shrinkage pore network model is extracted through the maximum ball algorithm. By applying the shrinkage pore network model, different formation lower limit RT values are set to eliminate the pores and throats below the lower limit value, and the corresponding shrinkage pore network model is built to calculate the physical parameters. With the increase of formation lower limit RT, the number of pore throats decreases, the porosity and permeability decrease, the average pore-throat radius increases, the aspect ratio and coordination number decrease, the connectivity function curve shifts to the right, and the pore network becomes less connected. When the formation lower limit is 20 μm, the pore/throat in the shrinkage pore network model is disconnected. This provides a basic platform for the study of the physical characteristics of shrinkage pores in tight sandy conglomerate reservoirs, which has important academic significance and practical application value.