Evaluation of In-situ Reservoir Blocking by Sodium Carbonate Gel Formed from Sodium Metasilicate Solution and Injected CO2 for CO2 Sequestration

• Published in: Journal of the Japan Petroleum Institute Vol. 62; no. 6; pp. 309 - 318
• Main Authors: SASAKI, Kyuro, SUGAI, Yuichi, CHEA, Samneang, NGUELE, Ronald
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Petroleum Institute 01.11.2019; Japan Science and Technology Agency
• Subjects: Analytical methods; Aqueous solutions; Aquifers; Calcium; Calcium ions; Carbon dioxide; Carbon dioxide fixation; Carbon dioxide sequestration; Carbon sequestration; Carbonates; Channeling; Electron microscopy; Enhanced oil recovery; Gas injection; Gas pressure; Gelation; Gels; Heterogeneous reservoir; In-situ blocking; Injection; Ion concentration; Oil recovery; Permeability; Pressure gradients; Reservoirs; Sandstone; Sedimentary rocks; Sodium; Sodium carbonate; Sodium carbonate gel; Sodium chloride; Sodium metasilicate solution; Sodium silicates; Stability; Temperature
• ISSN: 1346-8804; 1349-273X
• DOI: 10.1627/jpi.62.309

Preventing channeling flows during enhanced oil recovery targeting heterogeneous or fracture type reservoirs and leakage flows from saline aquifers containing CO2 remains a challenge. This study evaluated the potential of in-situ gelation as a blocking agent in a heterogeneous reservoir using the reaction between aqueous solution of sodium metasilicate (Na2SiO3 · 9H2O; S–MS) and dissolved carbon dioxide (CO2). Both Raman and scanning electron microscopy/energy dispersive X-ray (SEM-EDS) spectroscopy revealed that the gel was a sodium carbonate type (S–C-gel). Physical characterization of the S–C-gel including the gelation time, gel strength and stability, were investigated in respect of S–MS concentration, temperature, salinity (NaCl), divalent ion concentration (calcium, Ca2+) as well as CO2 injection pressure. Gelation time after CO2 gas injection was around 1 to 24 h depending on temperature and pressure. Gel strength increased with higher S–MS concentration (≤ 10 wt%) and CO2 gas pressure (≤ 5.5 MPa). Threshold pressure gradient (TPG) and gas permeability of the sandstone core filled with in-situ gel increased by 2.6 times and decreased about 1/10, respectively, compared with the water saturated core. These promising findings herein could be extended to CO2 sequestration.