A Novel Method to Construct Capillary Pressure Curves by Using NMR Log Data and Its Application in Reservoir Evaluation

By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are<br>found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized<br>index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of<br>capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and<br>estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed,<br>which could be used to evaluate reservoir pore structure and calculate reservoir originality water saturation in the intervals<br>with NMR log data. At last, the constructed NMR capillary pressure curve by this new method is used in well site to detect the<br>change in reservoir pore structure and initial water saturation as a function of depth, comparision among the calculated result,<br>core data and Archie water saturation, demonstrate the responsibility and accuracy.