Characterizing seismic elastic properties of deep cavity-fracture carbonate reservoir using digital rock physics
The deep fracture-cavity carbonate reservoir in the Tarim Basin has enormous potential for oil and gas resources.However,when drilling such reservoirs formations,drilling fluids loss and blowout frequently occur,making it difficult to obtain core samples and accurate logging data to characterize their seismic rock physics characteristics.Based on the actual drilling,imaging logging,and logging data in the Shunbei region at northern Tarim basin,this paper constructs a typical digital rock model exhibiting fracture-cavity reservoir characteristics.We study the relationship between elastic wave velocity and karst porosity and fracture density using static simulation methods.The results of the digital rock physics simulation show that the P-wave velocity of the deep reservoir containing cavity is significantly lower than that of the surrounding rock.Nevertheless,due to the strong pore stiffness of the cavity,the P-and S-wave velocities are not sensitive to the amount of filling material and changes in cavity porosity.Since the fracture stiffness is significantly lower,the P-and S-wave velocities of the fractured carbonate reservoir tend to decrease linearly with increasing fracture density in the carbonates.At the logging scale,the elastic wave velocities have a certain sensitivity to changes in filling material and porosity in the cavity.Based on the results of the digital rock physics simulation,a rock physics template characterizing relationship between elastic responses and porosity for deep carbonates reservoirs is constructed,providing rock physics guidance for quantitative seismic interpretation of deep carbonate reservoirs in the Tarim basin.
Deep formationCarbonatesCavity-fracturesDigital rock physicsElastic properties
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NSTL
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