Reservoir Inversion Method And Its Application Of Oil And Gas Detection Theory

In this paper, some presently popular theories, such as Gassmann theory, Biot theory and BISQ theory , are analyzed and compared based on the physical basis of seismic reservoir inversion and oil&gas detection , and following conclusions are brought forward: (1) Gassmann equation can be used in wave velocity measurement of seismic data( < 100Hz) and log data( ~ 10 Hz) while should be used as less as possible in ultrasonic measure data from laboratory( ~ 10 Hz) ; (2) The use of Biot theory is confined in saturated rocks of high porosity and permeability. It is no longer in point when there is uneven local flow of the liquid in rock pores while BISQ theory should be used, for it has well considered the "Local Flow' effect.(3) Gassmann equation, Biot theory and BISQ theory are only part solution to pore liquid effect. The more precise and complete solutions need farther study and development. Based on these conclusions, formulas of impedance to velocity, density, porosity and elastic coefficient are deduced by studying the relationships between velocity, density and petrol parameters ( porosity, permeability and saturability) of the reservoir as well as depth, rock age and pressure etc, The applying area of each formula are pointed out additionally.This paper discusses the probability of the inversions of reservoir's lithology, petrol parameters and oil&gas detection basing on the basic theory of wave reflection and Zoeppritz equation. The simplified formulas of some Zoeppritz equations in common use at present are analyzed and compared and two conclusions has been arrived at; (3)All the simplified formulas can be converted into each other under certain conditions. Their differences mainly lies in their parameters and their starting, aiming at strengthening the effects on reflection amplitude by the variance of these parameters and its sensibility. (2) The effect on reflection coefficient by elastic parameters is synthetic and is restricted by each other. The most sensible elastic parameters are shear modulus and volume elasticity. Only when combining all these methods can more accurate results be obtained in lighology parameters inversion and oil&gas detection.Aiming at solving the problems ( such as low horizontal and vertical resolution of the inversion results, multiple solutions and so on) in impedance inversion, a new methods is studied. The methods is; by using seismic data, log data, drilling data, VSP data and lithology analysis data together, a 3D optimization inversion method restricted by well model, geology model, seismic attributions and dynamic binning are adopted to obtain high accuracy 3-D impedance and other data volume 0 The method can be well used in the inversion of thin - bedded reservoir of shale sandstone in China. High computing velocity, high inversion accuracy and high vertical resolution up to 5m are its characteristics,,Aiming at solving the problems (such as that the wavelet for seismic inversion can not be calculated accurately, that the experiential formula for reservoir parameters converting have no high precision in calculation, that it is hard to mark off special lithology with impedance, etc) in conventional impedance inversion , it is mainly discussed in this paper how to create an integral set of non - linear log parameters inversion methods, which based on field theory, information - optimizing theory, information prediction theory and non - linear theory and restrained by seismic attributions, geology model and logging. The method can be used to obtain 2D,3D impedance and varieties of log parameters data volume with high resolution up to 2m or so0 It can well solve the problems of special lithology division, oil -water bounda-ry identification and reservoir dynamic monitoring.At present, the oil&gas bearing detection methods based on single - phase medium result in serious problems of multiple solutions. In this paper, basing on the theory of multiphase medium, the testing data of laboratory and BIOT theory, a theory is proposed that seismic wave spreading in o...