model to relate PWave attenuation to fluid flow in fractured tight 相关模型的P波衰减在裂缝性致密流体流动课件.pptVIP

* * A model to relate P-Wave attenuation to fluid flow in fractured tight gas sands, siliceous shales, and carbonate reservoirs Southwest Research Institute Jorge Parra and Chris Hackert, Southwest Research Institute Pei-Cheng Xu, Datatrends Research Introduction A modeling scheme is applied for the analyses of flow unit responses to evaluate acoustic/seismic measurement techniques. The responses are produced to determine the frequency band in which flow units can be observed and distinguished from scattering effects. The model estimates attenuation in a large broadband frequency range to include sonic, crosswell, VSP, and 3D seismic scales. Since flow units in a reservoir are characterized by permeability, porosity, and fluid saturation and the fluids are characterized by viscosity, density, and velocity, we use the theory of poroelasticity. This theory provides the physics involved in the interactions between the fluid and the rock matrix as an acoustic wave propagates in the medium. To represent the energy losses due to the presence of fluids in the formation, we use the unified Biot and squirt-flow mechanism. This work, implemented in a layered poroelastic medium with azimuthal anisotropy, is used to predict whether flow units intercepted by a borehole can be detected at seismic scales (crosswell, VSP and 3D seismic). To demonstrate the variability of the attenuation profile in different rock formations, we present attenuation profiles from fluid saturated rocks in four fields. These fields include the Siberia Ridge, a fractured tight gas sands in Wyoming; the Buena Vista Hills, a low permeability diatomite shale reservoir in California; the Ropes field, a carbonate reservoir in Texas; and a high permeability carbonate aquifer in Florida. Figure 1. The effect of frequency and azimuths on poroelastic attenuation for a global squirt flow length = 5 cm (representing fluid flow in cracks) and a local squirt flow length = 0.2 mm (representing fluid flow in th