CR Method For Oil And Gas Detection Mechanism And Extraction Method Of Spectral Parameter In Spectrum Induced Polarization

Complex resistivity method is a surface electric prospecting method by using frequency domain couple source developed in recent years.It is the only electromagnetic prospecting method that can directly indicate oil and gas reservoir.Complex resistivity method is mainly used to test and evaluate whether local trap or anomaly within a study area bears oil,to provide drilling target,to improve drilling success ratio,and to reduce the risk and cost of exploration and development.This method had been tested,pilot tested and large-scale used in Junggar Basin,Xinjiang oilfield in1999,2000and2002.In2003,in block9shallow heavy oil field of Karamay, preliminary inversion and various data processing result conform to the correlation result of oil and water layer in production wells. Based on the studies of the experimentation in recent years,we have gotten some satisfactory effects,and the Complex resistivity method is applied to directly indicate oil and gas reservoir has already shown an expected result,we should actively develop the research and application in this respect.However,the theory of using complex resistivity method directly to search for oil and gas resources is still constroversial.Therefore,for developing the experimental an theoretical studies of oil and gas reservoir exploration,exploring the polarization parameters of the oil and gas reservoir,inversion and interpretation data and directly indicating oil and gas reservoir have very important realistic meaning and practical value.Based on the summarizatin of previous work, accord ing to the characteristics of the induced polarization effect of rock,introducing mathematical-physical model that describe the rock induced polarization characteristics Cole-Cole model,it analyses and compares parameter influence of mathematical-physical model,Cole-Cole model amplitude spectrum and phase spectrum curve characteristics of the law with the changes in various parameters.Then over the electrical properties of the argillaceous sandstone samples were analyzed by experimental measurements,the researchers followed the law in the water saturation and oil saturation amplitude curve and phase curve,the obtained oil and gas accumulation induced polarization characteristics and which comply with the law.Analysis, validation and field measured data compared to oil and gas reservoir induced polarization phenomenon,to explore the direct use of the complex resistivity method to find the feasibility of the oil.With wide application of complex resistivity method,searching precise,rapid inversion algorithms has become the focus of complex resistivity research.The frequency spectrum of complex resistivity has shown great potential for use in geophysical prospecting. Selection of model and inversion of its parameters are difficult. Conjugate gradient method,which has several advantages such as global optimization,simple,and,tolerance of errors,can be used in the inversion of the complex resistivity model parameters.The idea for extracting spectral parameters with conjugate gradient method is put forward. Procedures for deriving the parameters with the algorithm are described,which is proven by using a theoretical model and actual data.The result shows that it is a feasible inversion method of spectral parameters in spectrum induced polarization.