Effect of halite (NaCl) on sandstone permeability and well injectivity during CO2 storage in saline aquifers

Beinashor, R

Abstract

Carbon dioxide capture and storage (CCS) is one of the widely discussed options for decreasing CO2 emissions. This method requires the techniques for capturing purification of anthropogenic CO2 from fossil-fuel power plants, subsequent compression and transport, and, ultimately, its storage in deep geological formations. Due to the high formation salinity, there is a substantial concern about the near well bore formation dry out as a result salt precipitation in the form of halite (NaCl). The focus was on one of the important physical mechanisms of CO2 injection into deep saline aquifers. The salt (mainly halite) will eventually fully saturate the brine causing the salt to start precipitating as solids. This solid precipitation could significantly decrease the porosity and permeability of the porous medium.


The investigations, in this study, were carried out in three distinct parts: (i) core flooding tests for different sandstone core samples (Bentheimer, Castlegate and Idaho Gray) which were saturated with different brine concentrations to measure the CO2 flow rate for different injection pressures, (ii) utilising simulated experimental apparatus to estimate the porosity and permeability of the core samples and (iii) Qualitative analysis of porosities using CT scanner.


In Part (i), it was found that the CO2 flow rates vary from 0.4 to 6.0 l/min when using brine solution concentrations of 10, 15, 20 and 26.4% for core flooding tests of the studied sandstone core samples before diluting concentrations with sea water (3.5%), and after diluting by sea water the flow rates vary from 0.6 to 7.0 l/min. The flow rate increase indicates that the injectivity will increase.


In part (ii), Helium Gas Porosimeter was used to calculate the porosity of each core sample and the results showed for Bentheimer, Castlegate and Idaho Gray 20.8 %, 25.6 % and 23.4 % respectively. Liquid saturating method was also used to calculate the porosity of each core sample and the results showed 23.6% for Bentheimer, 24.4% for Castlegate and 22.4% for Idaho Gray. Regarding the permeability impairment investigations for both brine permeability and gas permeability, the permeability damage took place due to the salt precipitation (NaCl) phenomenon. For brine permeability, the damage percentage of Bentheimer, Castlegate and Idaho Gray was 40%, 42% and 47%. For gas permeability the reduction due to dry out of saturated samples with 20% brine solution were calculated as 34.5% for Bentheimer, 42% for Castlegate and 50.2% for Idaho Gray.


Finally, in part (iii), CT Scan was used to determine each core sample porosity and the results showed 20.7% for Bentheimer, 24.3% for Castlegate and 24.6% for Idaho Gray.

Citation

Beinashor, R. Effect of halite (NaCl) on sandstone permeability and well injectivity during CO2 storage in saline aquifers. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Feb 16, 2018
• Publicly Available Date: Feb 16, 2018
• Award Date: Dec 8, 2017