Using laboratory data to understand how pore aspect ratio influences elastic parameters and amplitude variation with offset

Abstract

Pore geometry is an important parameter in reservoir characterization that affects the permeability of reservoirs and can also be a controlling factor on the impact of pressure and saturation on reservoirs elastic properties. We use SLS (Selective Laser Sintering) 3D printing technology to build physical models to experimentally investigate the impacts of pore aspect ratio on P-, and S- wave velocities and amplitude variation with offset (AVO). We printed six models to study the effects of the pore aspect ratio of prolate and oblate pore structures on elastic properties and AVO signatures. We find that the P-wave velocity is reduced by decreasing the pore aspect ratio (flatter pore structure), whereas the shear wave velocity is less sensitive to the pore aspect ratio. This effect is reduced when the samples are water saturated. We present new experimental and processing techniques to extract realistic AVO signatures from our experimental data and show that the pore aspect ratio has similar effects on AVO as fluid compressibility. This shows that not considering the pore aspect ratio in AVO analysis can lead to misleading interpretations. We further show that these effects are reduced in water-saturated samples.

Using a Synthetic Borehole Model to Determine the Pore Aspect Ratio Dependence of Velocities from Acoustic Well-Logging Data

“…In addition, pore AR has a remarkable effect on elastic wave propagation [36][37][38], affecting the energy exchange between the formation and pore fluids. However, recent researches only focus on building quantitative trends between the velocity and pore type at the core scale [8].…”