5:15 PM - 6:45 PM
[HSC07-P09] Preliminary study of seal capacity evaluation for CO2 capture and storage (CCS) using MICP (mercury injection capillary pressure)
Keywords:Geological CO2 Storage, MICP, seal capacity, threshold pressure
The evaluation of seal rock capacity, which is usually evaluated by capillary threshold pressure on core analysis, is one of the important considerations in CCS. However, the opportunities and depth intervals to take seal rock cores from CCS target formations are limited. In addition, core analysis usually requires several days, and it is not easy to increase the number of analyses.
On the other hand, the threshold pressure may be evaluated and estimated from the results of mercury injection capillary pressure (MICP) measurements using cuttings samples. If this evaluation method can provide the same results as core analysis, it would facilitate a broad and continuous evaluation of the sealing layer in the depth direction by expanding sampling opportunities and reducing measurement time (a few hours per sample). Mercury is continuously pressurized and injected into the sample pore in MICP, the capillary pressure curve and pore size distribution can be evaluated from the relationship between the mercury injection pressure (corresponding to pore diameter) and the mercury injection amount (mercury saturation in the pore). Usually, the inflection point of the capillary pressure curve or the maximum point of curvature on the low pressure side of the inflection point is estimated as the threshold pressure. From comparison of the threshold pressures measured by core analysis and MICP measurements on the same sample, it was showed that in some cases they were close to each other and in other cases they diverged.
In order to examine the difference between the evaluated values by core analysis and MICP, a simple two-dimensional simulation was performed. From the simulation results, it was confirmed that if the pore size distribution obtained by MICP measurement has a single sharp peak, the evaluation values are similar between core analysis and MICP, but if multiple peaks exist, the capillary pressure inflection points may also be multiple, making the evaluation difficult.
Further study by simulation is needed to find a way to deal with cases where evaluation by MICP is difficult such as multiple peaks. On the other hand, by conducting MICP measurements over a wide range of depth intervals, a more accurate method of evaluating the sealing layer capacity was also investigated based on trends in the measured data.
On the other hand, the threshold pressure may be evaluated and estimated from the results of mercury injection capillary pressure (MICP) measurements using cuttings samples. If this evaluation method can provide the same results as core analysis, it would facilitate a broad and continuous evaluation of the sealing layer in the depth direction by expanding sampling opportunities and reducing measurement time (a few hours per sample). Mercury is continuously pressurized and injected into the sample pore in MICP, the capillary pressure curve and pore size distribution can be evaluated from the relationship between the mercury injection pressure (corresponding to pore diameter) and the mercury injection amount (mercury saturation in the pore). Usually, the inflection point of the capillary pressure curve or the maximum point of curvature on the low pressure side of the inflection point is estimated as the threshold pressure. From comparison of the threshold pressures measured by core analysis and MICP measurements on the same sample, it was showed that in some cases they were close to each other and in other cases they diverged.
In order to examine the difference between the evaluated values by core analysis and MICP, a simple two-dimensional simulation was performed. From the simulation results, it was confirmed that if the pore size distribution obtained by MICP measurement has a single sharp peak, the evaluation values are similar between core analysis and MICP, but if multiple peaks exist, the capillary pressure inflection points may also be multiple, making the evaluation difficult.
Further study by simulation is needed to find a way to deal with cases where evaluation by MICP is difficult such as multiple peaks. On the other hand, by conducting MICP measurements over a wide range of depth intervals, a more accurate method of evaluating the sealing layer capacity was also investigated based on trends in the measured data.