Participation in more than 80 carbon capture and sequestration (CCS) projects spanning 25 years has led to the evolution of a recommended well-based appraisal workflow for CCS in saline aquifers. Interpretation methods are expressly adapted for CCS applications to resolve key reservoir parameters, constrain field-scale modeling, provide answers required for the permitting process, and derisk the three principal CCS evaluation challenges: storage capacity, injectivity, and containment. Each of these may be further complicated by eventual three-way interaction between rock matrix, brine, and CO₂ streams.

Many logging and core analysis techniques for CCS are borrowed or adapted from oil and gas exploration and other related industries, but interpreting and putting the data to use requires an entirely new mindset. In hydrocarbon exploration, petrophysicists have become adept at acquiring and interpreting downhole measurements to quantify existing fluid saturations. In a CCS project, there is no saturation to measure—it doesn’t exist yet, but it is critical to predict its future value. In another example, once a hydrocarbon discovery is made, a good seal is implied. In aquifer CCS projects, the seal has never been put to the test, but is a critical element of the storage complex. In addition to adapted log and log-interpretation techniques, fit-for-purpose developments in laboratory analysis are especially important, and the possible impact of CO₂ exposure to key reservoir properties over time must always be considered. This is investigated via unique special core analysis (SCAL) workflows, with results projected decades or centuries into the future using digital SCAL models.

Integration of these results into a dynamic simulation model can predict hydraulic, mechanical, chemical, and thermal changes, which helps to effectively lower the risk of your CCS projects.