Quantitative Seismic Interpretation Of Reservoir Brittleness Based On Statistical Rock Physics

Brittleness of shale-gas reservoir is an important property for hydraulic fracturing.This paper pays attention to how to evaluation brittleness properly.There are so many brittleness evaluation methods.Considering the disadvantage of existing brittleness evaluation methods that suitable for geophysics,we introduce statistics rock physics to quantitatively interpret brittleness of reservoir.The main results of this paper can be summarized as follows:(1)Detailed quantitative seismic interpretation technique,containing a whole interpretation flow,rock physics,statistics,inversion and seismic attributes analysis,and geostatistics.This technique has been applied to a practical data to describe how to combine multiple subject knowledge to interpret seismic data accurately.We present how to identify lithofacies according to well-log data and build relationships between lithofacies and seismic attributes.Also,pattern identify methods is presented to classify lithofacies of seismic data.Simultaneously,ray impedance is introduced as a seismic attribute.(2)After several usual brittleness evaluation methods have been presented,we evaluate the brittleness of shale based on two common criteria related to geophysics:(1)the clay content and(2)the elastic modules,such as Young's modulus and Poisson's ratio.The former relates to the mineralogy of shale,while the latter is determined by not only the elastic properties of single minerals,but also the microstructure and pore-fluid properties of shales.Therefore,two criteria provide different result in the interpretation of brittleness.We analyze the advantages and disadvantages of the two criteria and interpret the similarities and differences based on rock physics theory.Meanwhile,anisotropy of shale is discussed for how to influence brittleness.(3)We implement a quantitative seismic interpretation method of reservoir brittleness based on statistics rock physics.The above two brittleness evaluation criteria are introduced to quantitative seismic interpretation based on the statistics rock physics and integrate the advantages of the two criteria to interpret brittleness more reasonable.