Quantitative Characterization of Petrological and Pore Throat Parameters of Conventional and Unconventional Sandstone and Carbonate Reservoirs Using Image Modelling

Abstract

Pore structure plays an important role in the exploration and development of both conventional and unconventional reservoirs. An algorithm using MATLAB is established to characterize the particle sizes, porosity, microscale and nanoscale pore throat radius, and cement contents in conventional and unconventional reservoirs. Samples from Carboniferous tight sandstone reservoirs and Ordovician carbonate reservoirs in the southeastern Ordos Basin are selected to explore the applicability of this algorithm. The quantitative analysis data obtained from images with MATLAB are compared high-pressure mercury intrusion and X-ray diffraction experimental results, and corresponding error curve and fitting curve equations are established. These results show that the correlation coefficients (R2) of the porosity, particle size and calcite cement content of the sandstone reservoirs were 0.9216, 0.7105 and 0.8430, respectively. The calculated porosities of the three main carbonate reservoir types, namely, carbonate reservoirs with intergranular pores, dissolved pores and bioclastic pores, fit the measured data well, with R2 values of 0.9515, 0.9285, and 0.9579. This quantitative analysis workflow provides a new characterization method for reservoir pore throat parameters using a single thin section image and MATLAB and is applicable to not only conventional reservoirs but also tight sandstone and carbonate reservoirs with intergranular and dissolution pores.