Elastic and Electrical Dual Pore Shape Modeling in the Mesa Verde Group

Ou, Liwei (Colorado School of Mines) | Wempe, Wendy (Colorado School of Mines)



In tight sand reservoirs, a significant amount of reservoir fluids can be held in small, open, inter-granular, micro-cracks that connect larger pores. Determining the conditions required to either mobilize or immobilize the fluids in those micro-cracks can have significant economic implications, whether those fluids are oil or water. When a reservoir experiences a change in effective stress, for example from production (increased effective stress) or flooding (decreased effective stress), then knowing which pores are changing in volume with respect to a change in effective stress can provide insight into changes in the mobility of the micro-crack fluids and the overall contribution of those micro-cracks fluids to fluid transport. Mechanically, the change in porosity in clean, tight sand that accompanies a change in effective stress can be explained by changes in compliant, micro-crack porosity and aspect ratios. In this paper we take an experimental approach to explore whether or not elastic and electrical Self Consistent Approximation (SCA) modeling can be used together to predict changes in porosity and/or aspect ratios in a dual pore system of micro-cracks and nearly-spherical pores.