Reserch On Matrix-conducting Shaly Sand Frequency Dispersion Experiment

With the development of oil and gas exploration,The direction of exploration and development has shifted from the simple high amplitude structural reservoirs to low porosity,low permeability,low resistivity,complex lithology and complex reservoir space.Low resistivity reservoirs have become an important source for increase of oil reserves and oil production in oil field.The genetic types of low resistivity reservoirs are various,and matrix conduction is one of the major causes of low resistivity reservoirs.Therefore,the reserch on conductive characteristics of matrix-conducting shaly sand is beneficial to the development of oil and gas reservoirs.First,12 artificial samples with different pyrite content and different shale content were designed and pressed in this paper.Second,using multiple frequencies core electricity experiment date under different water saturation,multiple frequencies core electricity experiment date under different salinity of formation water and the experiment date of analysis of total mineral in X diffraction of this group of samples to study the influence of frequency on the matrix-conducting shaly sandstone.The results show that both pyrite and shale has frequency dispersion,and with the increase of the current frequency,the phase conductivity of rock sample increases gradually.On the basis of this study,a new matrix-conducting shaly sand frequency resistivity dispersion model is proposed basing on symmetrical effective medium conductance theory,in this model,matrix-conducting shale sands are divided into nonconducting matrix grains,conductive matrix grains,shale,oil and water.Moreover,the effect of pyrite content,conductivity of pyrite,shale content,shale conductivity under different frequencies is studied.Then,unknown parameters in the model is requested with phase conductivity of 12 artificial samples under 1KHz~20KHz and optimization method.The model has a high fitting accuracy with the experimental data,It is proved that the model established in this paper can describe matrix-conducting shaly sandstone resistivity frequency dispersion Finally,with the matrix-conducting shaly sand frequency resistivity dispersion model,varied current frequencies of well logging are chosen to establish multiple matrix-conducting shaly sand frequency correction charts and high frequency resistivity logging resistivity is corrected by this chart.