Microbial Treatment for Prevention and Removal of Paraffin Deposition on the Walls of Crude Pipelines

Abstract

Two bacterial strains, paraffin removal strain and biosurfactant-producing strain, named BHJ-1 and QFL-1, were isolated from oil production wells in Daqing oilfield of China. They were subsequently identified as Bacillus cereus QAU68 and Bacillus subtilis XCCX, respectively. As an indicator of the degradation paraffin, the inoculum concentration of BHJ-1 and QFL-1 were added in different proportions, the optimum proportion was 5:2. In this proportion the degradation rate of paraffin could reach 64 %, the prevention rate of paraffin could reach 55 %.Keywords Paraffin Á Bacillus cereus Á Bacillus subtilis Á Degradation Microbial treatment method of paraffin deposition has been used as a sustainable replacement to conventional treatment methods (chemical, mechanical and thermal methods) [1,2]. Industrial scale tests were accomplished in Jidong, Daqing, Liaohe and Zhongyuan oilfields in China [3], but there is no large-scale application by microbial treatment on the whole, the reasons for restricting the large-scale application are short of validity period and less efficiency. Adding special biosurfactant can lower the interfacial tension as their primary activity [4,5], increase the hydrocarbon concentration in the water [6,7], therefore adding the special biosurfactant may be propitious for combination of crude oil and bacterial liquid, prolong the validity period, increase the efficiency of microbial treatment and paraffin deposition.During this study two isolates, paraffin removal strain and biosurfactant-producing strain, named BHJ-1 and QFL-1, were isolated from oil production wells in Daqing Oilfield of China. BHJ-1 was isolated from enrichment salts medium (ESM) containing 0.5 % (w/v) of crude oil. The system was operated at the following parameters: temperature 37°C, pH 7.2, incubation period 7 days. In order to isolate oil-utilizing microorganisms, 0.1 ml of culture supernatant was transferred every 24 h onto nutrient agar plates [8]. QFL-1 was isolated from ESM and it was cultivated at orbital shaking (180 rpm) at 37°C for 72 h. The culture fluid was spread on the cetyl tri ammonium bromide-methylene blue agar medium and cultivated at 37°C for 9 days. Then, the colonies of the halo were extracted, streaked on crude oil agar medium and cultivated at 37°C for 9 days. After five times plate streak, the pure strains could be purified [9]. The isolates were stored in isosensitest broth at 4°C and were plated in Isosensitest agar for further investigation [10]. The photo of scanning electron microscope is shown in Fig. 1. Phylogenetic tree was constructed and analysis was done by neighbour joining method through MEGA 5 software (Fig. 2). Partial sequencing with both primers revealed that the closest matches, determined by a BLAST search, corresponded to Bacillus cereus QAU68 (99 % similarity, BHJ-1) and Bacillus subtilis XCCX (99 % similarity, QFL-1), respectively [11,12].As an indicator of the degradation of paraffin, BHJ-1 and QFL-1 were added in different proportions. The

Methanogenic Paraffin Biodegradation: Alkylsuccinate Synthase Gene Quantification and Dicarboxylic Acid Production

“…S2). Interestingly, biosurfactants have also been explored as an alternative for the chemical surfactants in paraffin treatment (10,11). As such, the ␣,-dicarboxylic acids produced by the methanogenic culture described here could potentially be explored for the treatment of paraffin.…”

“…These types of crude oils are found worldwide but can cause problems during oil recovery operations (10). Deep within crude oil reservoirs typically characterized by relatively high temperatures and pressures, waxy alkanes remain dissolved in the oil phase, but as the crude oils are recovered to the surface, they are exposed to lower temperatures and pressures, causing the waxy paraffins to solidify around the production well bore and impede oil recovery (10)(11)(12)(13).…”

“…Chemical, mechanical, and thermal methods have been used to remove paraffin; however, all are costly and dangerous, and some provide only partial paraffin removal (13). Because of this, there has been interest in applying microbial strategies for down-hole paraffin treatment (10)(11)(12)(13). The use of microorganisms to treat wax accumulations has received some attention, predominantly under aerobic conditions (2,9).…”

Biosurfactant from Pseudomonas species with waxes as carbon source – Their production, modeling and properties

“…Acquaviva et al [51] observed 43% n-eicosane degradation with Corynebacterium species. Liu et al [52] observed 64% paraffin degradation with two Bacillus species. Bordoloi and Konwar [3] reported that the degradation of hydrocarbon is connected with the biosurfactant adsorbed and the CSH.…”

Microbial Biodegradation of Paraffin Wax in Malaysian Crude Oil Mediated by Degradative Enzymes

“…Microbes play essential roles in bioremediation of oil, and many studies have been published on microbial remediation to degrade paraffin wax in crude oil. However, most of these microorganisms were mesophilic bacteria such as Bacillus cereus QAU68 and Bacillus subtilis XCCX (Liu et al, 2013); Pseudomonas aeruginosa B1 and Acinetobacter junii B2 (Liu et al, 2012); and Rhodococcus sp. Moj-3449 (Binazadeh et al, 2009).…”