Enhancing residual trapping of supercritical CO₂ via cyclic injections

Abstract

We utilize synchrotron X‐ray tomographic imaging to investigate the pore‐scale characteristics and residual trapping of supercritical CO2 (scCO2) over the course of multiple drainage‐imbibition (D‐I) cycles in Bentheimer sandstone cores. Capillary pressure measurements are paired with X‐ray image‐derived saturation and connectivity metrics which describe the extent of drainage and subsequent residual (end of imbibition) scCO2 trapping. For the first D‐I cycle, residual scCO2 trapping is suppressed due to high imbibition capillary number (Ca ≈ 10−6); however, residual scCO2 trapping dramatically increases for subsequent D‐I cycles carried out at the same Ca value. This behavior is not predicted by conventional multiphase trapping theory. The magnitude of scCO2 trapping increase is hysteretic and depends on the relative extent of the sequential drainage processes. The hysteretic pore‐scale behavior of the scCO2‐brine‐sandstone system observed in this study suggests that cyclic multiphase flow could potentially be used to increase scCO2 trapping for sequestration applications.

Enhancement of CO2 trapping efficiency in heterogeneous reservoirs by water‐alternating gas injection

“…Furthermore, and importantly, these characteristics’ curves, and the associated residual gas and water saturations were modified based on Herring et al .’s data for the WAG scCO 2 ‐brine floods (Figs. and ).…”

“…For the first WAG cycle we used the values of the Sco 2 r (residual CO 2 saturation) and Sco 2 i (initial CO 2 saturation) of the intermediate‐wet rock. Then for cycles 2–5 the Sco 2 r was enhanced based on the experimental studies . For all the five WAG cycles the relationship of the Sco 2 r versus Sco 2 i followed Pentland's et al .…”

“…Derived from Al‐Khdheeawi et al . and extended for different WAG cycles based on the experimental studies …”

The effect of designing parameter of WAG injection on enhancement of CO2 trapping in heterogeneous formations: A numerical study

“…Several studies have investigated the optimization of the WAG technique to improve oil production while keeping the injection costs reasonable . In the context of CO 2 geological storage, the WAG technique has been studied using experimental methods and numerical modeling …”

“…While based on core scale experiment, Saeedi et al . reported that residual gas saturation is independent of the number of cycles, Herring et al . found by pore‐scale experiments that an increase in the number of injection cycles can enhance residual trapping.…”