Reservoir souring control using benzalkonium chloride and nitrate in bioreactors simulating oil fields of western India

• DOI: 10.1016/j.ibiod.2018.04.017
• Publication Date: 2018-05-26T02:34:15Z
• Authors: Ganshyam Prajapat; Sandeep Rellegadla; Shikha Jain; Akhil Agrawal
• Keywords: Benzalkonium chloride; Produced water; Sulfate-Reducing Bacteria

Abstract Oilfields located in western India produce crude by injection of large amounts of water during secondary oil recovery. This water is obtained from underground aquifer and contains 5 mM sulfate approximately. Sulfate present in this water is converted in to sulfide by sulfate reducing bacteria (SRB) present in the reservoir. Increased concentration of sulfide in the production fluid negatively impacts oil production and is known as reservoir souring. Most probable number and quantitative PCR enumerated 103-108 SRB ml−1 in various field installations. Isolates from produced water in sulfate containing medium showed similarity with Desulfotomaculum, Desulfomicrobium and Thermodesulfobacterium genera. Similarly, isolates from produced water in nitrate containing medium were related to Tepidiphilus, Paenibacillaceae, Kocuria and Thauera genera. In the present study four sand packed bioreactors simulating moderately high temperature oil reservoir were used for different souring control treatments. Results revealed that continuous injection of 4 mM nitrate or 1.5 mM benzalkonium chloride (BAC) was not able to control souring. However, co-injection of 2 mM nitrate and 0.75 mM BAC completely ceased sulfide production and controlled souring.