Experimental And Methodology Stduy On Calculating Capillary Pressure From Resistivity Logging Data

For the low porosity and permeability or strong heterogeneity complex reservoirs,capillary pressure data measured using experimental methods become difficult to operate,and expensive.Resistivity logging data can be obtained easily,and capillary pressure as well as resistivity are functions of wet-phase saturation,theoretically there should be some connection between this two parameters,if this relationship can be found,one can finally calculated capillary pressure by using resistivity dataIn this paper,a series of theoretical analysis and experimental study for the relationship between capillary pressure and resistivity were conducted Based on Li-Williams model,the mathematical model between capillary pressure and resistivity was established,and the reservoir division was done accurately,the achievements at present are as follows:the porosity of reservoir rocks in target area ranged from 20%to 31%,which means reservoir performance is very well;equivalent liquid permeability maximum 973.170 md,minimum 9.675 md,most less than 578 md,belonging to the lower penetration the reservoir conditions.capillary pressure associated with the resistivity measurement experiments showed that:the target area of the rock sample capillary pressure curves,each with a different shape,irreducible water saturation ranged from 16.73%to 37.49%,vs.resistivity index and water saturation meet Archie formulas,saturation exponent n values ranged from 1 to 2.3;capillary pressure and normalized water saturation curves meet Brooks-Corey model,valve pressure between 0.0057 MPa?0.0178 MPaTarget area rock sample capillary pressure curve and resistivity index exponential relationship,data fitting model based on Li,get rock kind of relationship index ? value between 1.3 to 3.0,in line with the initial establishment of the reservoir characteristics of the target area rock capillary pressure and resistivity mathematical model;rock samples p value increases with the rock permeability decreases.The scope of the rock sample pore size distribution index ? value,the target area can be divided into four levels of reservoirs(?-? class category),the greater the ? value,rock samples smaller displacement pressure,permeability more large ? class reservoir ? value of the minimum,represents a very strong heterogeneity of reservoir conditions.