Porosity analysis based on the CT images processing for the oil reservoir sandstone

Sandstone is widespread in the world as the main storage place for oil and gas. The pore structure characterization of the reservoir sandstone is crucial for oil and gas production. Porosity is the ratio of the pore space volume to the total volume of the rock, and it is one of the key parameters of the pore structure. X-ray computer tomography (CT) is often used as an effective tool to investigate the pore structure of the rock in the recent years. Porosity analysis is the key for the CT grayscale images segmentation. The accurate choice of the threshold valve for the binary CT images is also essential. The maximum variance method (OSTU) of the threshold valve in the image processing is presented in the CT images binary and segmentation in the paper, where the measure porosity with air (He) as a constraint condition. The porosity calculation from 2D CT images processing shows that OSTU threshold valve method constrained with the known porosity avoid the random comparing from the water porosity and the air porosity.