Abstract: When measuring the capillary pressure of any irregular or small core samples, the accuracy is depended on the mercury blind pore volume. On the base of studying the mercury blind pore volume phenomenon, a new method by using the cubic splines interpolating function to calculate the mercury blind pore
volume comes on. Thus, it is easy to get the right value of mercury blind pore volume of olitic carbonate rocks in Feixianguan Formation, Luojiazhai gas field, in northeastern, Sichuan, China. Based on analyzing the influence of the mercury blind pore volume, the capillary pressure curves are corrected, so the quality is improved and the application of the capillary pressure curves is expended.

Key words: capillary pressure curves, mercury blind pore volume, cubic splines interpolation