Abstract
Fluid discrimination is an extremely important part of seismic data interpretation. It plays an important role in the refined description of hydrocarbon-bearing reservoirs. The conventional AVO inversion based on Zoeppritz’s equation shows potential in lithology prediction and fluid discrimination; however, the dispersion and attenuation induced by pore fluid are not fully considered. The relationship between dispersion terms in different frequency-dependent AVO equations has not yet been discussed. Following the arguments of Chapman, the influence of pore fluid on elastic parameters is analyzed in detail. We find that the dispersion and attenuation of Russell fluid factor, Lamé parameter, and bulk modulus are more pronounced than those of P-wave modulus. The Russell fluid factor is most prominent among them. Based on frequency-dependent AVO inversion, the uniform expression of different dispersion terms of these parameters is derived. Then, incorporating the P-wave difference with the dispersion terms, we obtain new P-wave difference dispersion factors which can identify the gas-bearing reservoir location better compared with the dispersion terms. Field data application also shows that the dispersion term of Russell fluid factor is optimal in identifying fluid. However, the dispersion term of Russell fluid factor could be unsatisfactory, if the value of the weighting parameter associated with dry rock is improper. Then, this parameter is studied to propose a reasonable setting range. The results given by this paper are helpful for the fluid discrimination in hydrocarbon-bearing rocks.
Highlights
Rock physics is an effective tool for studying reservoir petrophysical properties from elastic and anelastic parameters [1]
The results show that the pore fluid can bring more attenuation to Russell fluid factor, Lamé parameter, and bulk modulus, compared with P-wave velocity
The study of dispersion term of elastic parameter can be beneficial for fluid discrimination
Summary
Rock physics is an effective tool for studying reservoir petrophysical properties from elastic and anelastic parameters [1]. Geofluids saturation brings about higher attenuation value than full saturation, and the characteristic frequency on fluid mobility follows the theory of squirt flow Based on these arguments, the Chapman model [16] is used to analyze the dispersion and attenuation of elastic parameters in the seismic frequency band in this paper, and the cracks are considered to be randomly arranged. The elastic parameter inversion based on Zoeppritz’s equation does not consider the effect of dispersion and attenuation caused by pore fluid. The results show that the pore fluid can bring more attenuation to Russell fluid factor, Lamé parameter, and bulk modulus, compared with P-wave velocity This is critical for us to decide which dispersion term to be used in the FAVO inversion. In order to improve the antinoise ability of the inversion, l1 norm regularization term [45] is applied
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have