The Study On The Relationship Between The Attenuation And The Reflection Coefficient In Sulige Tight Gas Reservoirs

With the deepening of the exploration and development of domestic reservoirs,tight sandstone reservoirs have begun to enter the researchers' vision.Tight sandstone gas reservoirs in China are widely distributed and contain huge exploration potential.The most typical of these is the tight sandstone reservoirs in the Sulige of the Ordos Basin.But the tight sandstone reservoirs in the Sulige have small pore spaces,various types,complex structures,strong heterogeneity,and thin interlayer development,so the different reservoir parameters and fluid properties need to be combined for guidance and analysis.This paper first studies the dispersion phenomenon based on the White model at the mesoscopic scale,and studies the effects of porosity,permeability,and saturation on seismic wave velocity and attenuation.Afterwards,the parameters are adjusted to make it possible to simulate the characteristics of tight sandstone.Then,the feasibility of studying the dispersion by the reflection coefficient equation based on the Carcione method is verified by numerical experiments.Next,the White model and the reflection coefficient equation based on the Carcione method are combined by Backus average to obtain the frequency-dependent reflection coefficient in the porous elastic medium.Based on this,forward modeling is performed to simulate the frequency-dependent AVO and analyze the attenuation and dispersion characteristics of tight sandstone reservoirs.Frequency-dependent AVO attributes are obtained by SVD to form a method for identifying gas reservoirs.Finally,by analyzing the actual work area,the prestack frequency-dependent attributes are obtained to guide the gas layer identification.