Integrated Multiscale Research of Fluid Flow in Shale: Molecular-to-Core Scales

Abstract

One of the great challenges in modeling fluid flow in shale system is the existence of heterogeneities at different scales. While the goal is to predict gas and oil production from a well, we learned that processes at the very small scale control the flow. At the molecular scale the interaction of fluid molecules with pore inner walls control the process. We have measured interactive forces and performed extensive molecular dynamics simulations (MD) to study fluid molecules interactions with pore walls. At the pore scale, SEM images reveal the locale of the pores and by using image analysis we extracted important information about pore geometries. We also utilize high pressure mercury injection capillary pressure (MICP) and low pressure nitrogen sorption tests to learn about porosity and pore size distribution in shale samples. Information about interactive forces, pore size distribution, pore geometry, porosity, and TOC are input data in our models and apparent permeability is the model prediction. We present a realistic model that honors heterogeneity of organic matter patchiness and its effect on apparent permeability. We validated our model using a set of detailed experimental data on shale samples. These results suggest that heterogeneity at small scale could affect the permeability at core scale and pore sizes corresponding to each compartment; organic and inorganic should be considered to estimate permeability. The model results also confirm permeability enhancement during sorption process in organic matter below critical sorption pressure.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018