Study On Intelligent Joint Measurement System Of Complex Resistivity Spectrum And Capillary Pressure

The capillary pressure curve and electrical parameters of rocks are important basic data in oil and gas exploration and development,and experimental data can be obtained through the joint measurement of capillary pressure and resistivity.There are many methods to measure the capillary pressure curve,among which the semi-permeable diaphragm method is the closest to the actual formation environment and its measurement accuracy is relatively high,so the joint measurement system generally uses the semi-permeable diaphragm method to measure the rock pressure curve.A large number of petrophysical experiments have shown that rock complex resistivity spectrum is related to rock pore structure and fluid properties.The combined measurement of rock complex resistivity spectrum and capillary pressure can better reveal the characteristics of rock pore structure.However,there is no joint measurement system of complex resistivity spectrum and capillary pressure,and the semi-permeable diaphragm method has the disadvantage that the measurement period is too long.Therefore,this paper focuses on the research on the intelligent joint measurement system of rock complex resistivity spectrum and capillary pressure.Through the analysis of system functions,a set of intelligent joint measurement system of rock complex resistivity spectrum and capillary pressure is designed and built.The software control system of the joint measurement system is designed and written,which can carry out remote independent control and linkage control of each functional module.At the same time,the joint measurement system can classify the types of capillary pressure curves of the complex resistivity spectrum of water-saturated rocks,and provide the differential pressure measurement sequence and the minimum number of measurement points,thereby improving the measurement efficiency.Based on the number of characteristic points of the capillary pressure curve,a new method for classifying the capillary pressure curve is proposed.The new classification method is not limited to the physical parameters of the sample itself,but pays more attention to the curve characteristics of the capillary pressure curve.Therefore,the new method is more suitable for the classification of capillary pressure curves in the process of petrophysical measurement.Based on the complex resistivity spectrum of the saturated sample,the artificial intelligence classification model is used to classify and predict the capillary pressure curve of the sample to be tested,and the differential pressure measurement sequence is set.The complex resistivity spectrum and capillary pressure of different samples were measured by the joint measurement system,and the characteristic changes of the measurement curves were consistent with the changes of rock physical properties,indicating that the joint measurement system measured the correct measurement curves.By analyzing the measured data,it is found that there are many characteristic parameters related to the capillary pressure curve on the complex resistivity spectrum curve.A new complex resistivity dispersion model parameter is found,which can simultaneously characterize the amplitude and frequency variation characteristics of electrical dispersion,and this parameter has a strong correlation with rock capillary pressure.The relaxation time distribution spectrum of the complex resistivity spectrum curve of the rock is obtained by using the relaxation time decomposition method,and the relationship between the relaxation time and the rock pore structure and fluid properties is discussed.A variable temperature joint measurement experiment was carried out on a core sample.The experimental results show that with the increase of temperature,the capillary pressure of the rock decreases,and the complex resistivity spectrum also shows a trend of decreasing amplitude.In conclusion,the establishment of the complex resistivity spectrum and capillary pressure intelligent joint measurement system is helpful to further study the characteristics of rock pore structure.