New Mexico Geological Society Annual Spring Meeting — Abstracts

CO₂ injectivity and storage capacity in sandstone may be impacted by fluid-rock interaction and resultant compaction during carbon sequestration. Although chemical, mineralogical and petrophysical changes are well characterized during fluid-rock interaction in CO₂-rich systems, the coupling of CO₂-driven alteration of sandstone with mechanical property changes is less known. Six flow-through experiments were conducted on Pennsylvanian Morrow B Sandstone cores from the Farnsworth Unit in West Texas, USA. CO₂-rich brine flowed through core samples of poikilotopic calcite- and disseminated ankerite-siderite-cemented sandstone at flow rates that ranged from 0.01 to 0.1 ml/min at 71°C and 29.0 MPa pore fluid pressure. Fluid sample analysis performed by ICP-OES from experiments on both carbonate-cemented sandstones indicate that carbonate cement dissolution is likely the dominant chemical process. The permeability of the ankerite-siderite-cemented sandstone changed little from the reaction with carbonic acid, whereas the permeability of the calcite-cemented sandstone significantly increased by more than one order of magnitude (from 3.3×10^-18 to 7.8×10^-17 m²). P- and S-wave velocities measured from pre- and post-experiment ultrasonic tests were used to estimate the changes in dynamic Young’s and shear moduli. Furthermore, cylinder-splitting tests were conducted to measure the tensile strength of the altered post-experimental samples and compared to the control samples that only interacted with pure brine. All samples underwent slight decreases in Young’s and shear moduli, and the cylinder-splitting tests suggest that mechanical degradation may be concentrated on the upstream end of the calcite-cemented sample. Our findings help in predicting chemo-mechanical changes at carbon sequestration sites where the reservoir lithology is carbonate-cemented sandstone.

Funding for this project is provided by the U.S. Department of Energy's (DOE) National Energy Technology Laboratory (NETL) through the Southwest Regional Partnership on Carbon Sequestration (SWP) under Award No. DE-FC26-05NT42591. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.