Considerations on the possibility of microbial clogging of re-injection wells of the wastewater generated in a water-dissolved natural gas field

• Published in: International biodeterioration & biodegradation Vol. 81; pp. 35 - 43
• Main Authors: Sugai, Yuichi, Sasaki, Kyuro, Wakizono, Ryo, Higuchi, Yasunori, Muraoka, Noriyuki
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2013
• Subjects: Backwashing; Bacteria; Bacterial corrosion; Column experiment; Dissolution; Dissolved oxygen; ferric hydroxide; Ferric hydroxide colloid; Iodide-oxidizing bacteria; iodine; iron; Microbial clogging; microbial growth; Microorganisms; Natural gas; oxidants; Plugging; Re-injection; Reservoirs; Salt water; Sand; subsidence; sulfuric acid; Waste water; wastewater; Wells; Microbial clogging; Re-injection; Iodide-oxidizing bacteria; Dissolved oxygen; Column experiment; Ferric hydroxide colloid
• ISSN: 0964-8305; 1879-0208
• DOI: 10.1016/j.ibiod.2012.10.003

Brine produced from water-dissolved natural gas reservoirs should be returned to the reservoirs after the resources are recovered to prevent land subsidence. However, the ability to re-inject the brine gradually decreases and is only rectified by carrying out backwashing treatment of re-injection wells. Because the brine contains high levels of iodine also, it is also recovered from the brine using sulfuric acid and oxidizing agents. These chemicals may stimulate the growth of microorganisms that may cause the clogging. In this study, we used column experiments to investigate the possibility of the microbial clogging. Significant clogging was observed on the columns that were treated by the brine containing both indigenous microorganisms and dissolved oxygen. In particular, iodide-oxidizing bacteria were detected from the columns and original brine dominantly; therefore, it was assumed to have an important influence on the clogging. Iodine that was produced by iodide-oxidizing bacteria corroded iron in the sand under the presence of dissolved oxygen. Eluted Iron formed ferric hydroxide colloid in the brine and it caused the clogging of the pore spaces. We also demonstrated that deoxidized brine inhibited the iodide-oxidizing bacteria from becoming dominant and the column from the clogging through the column experiments. From these results, we can suggest removing dissolved oxygen as the most feasible countermeasures for the clogging. ► Microbial clogging of re-injection wells of wastewater was considered by column tests. ► Iodide-oxidizing and/or sulfate-reducing bacteria elute iron from reservoir rock. ► Eluted iron forms ferric hydroxide colloid that causes the clogging of reservoirs. ► Deoxidized brine inhibited the iodide-oxidizing bacteria from becoming dominant. ► Dissolved oxygen in wastewater should be removed to prevent the microbial clogging.