Arends, Olivia (Stepan Company) | Seymour, Brian (Stepan Oilfield Solutions) | Benko, Brandon (Stepan Company) | Elshahed, Mostafa (Oklahoma State University) | Yakoweshen, Lynn (Stepan Oilfield Solutions) | Ganguly-Mink, Sangeeta (Stepan Company)
Microbial-induced problems in oil and gas incur high costs and cause severe environmental and safety concerns. Most of these problems are directly caused by surface-adhered bacteria colonies known as biofilms. Distinct populations of bacteria within a biofilm can symbiotically alter surrounding conditions that favor proliferation to the extent that leads to corrosion, plugging, and H2S souring. Biocides are antimicrobial products used to eliminate and prevent bacterial growth. The purpose of this initial study is to measure performance of biocides against anaerobic planktonic and sessile bacteria. The three anaerobic conditions tested were biocide performance against planktonic bacteria, against established biofilm, and inhibition of biofilm growth.
Biocides containing two types of quaternary ammonium compounds and blends with glutaraldehyde were evaluated against sulfate reducing bacteria (SRB) and acid producing bacteria (APB) in both planktonkic and sessile forms. As expected, all of the biocides tested were effective against planktonic bacteria. Quaternary type biocides were found to be particularly effective at controlling sessile anaerobes. Surprisingly, the addition of glutaraldehyde did not appear to provide synergistic benefits and actually had a negative dilutory effect on the performance against biofilms. In all cases, dialkyl dimethyl ammonium chloride (DDAC) was the most efficient biocide in controlling all bacterial forms tested, both planktonic and sessile.
Eibergen, Nora (The Dow Chemical Company) | Maun, Philip (The Dow Chemical Company) | Caldwell, Brittany (The Dow Chemical Company) | Widera, Imke (The Dow Chemical Company) | Morris, Brandon E. L. (The Dow Chemical Company) | Wunch, Kenneth (The Dow Chemical Company) | van der Kraan, Geert M. (The Dow Chemical Company)
The pipelines and vast infrastructure required for the production and transport of oil and gas are largely constructed of carbon steel. This material is highly susceptible to damage and failure as a result of direct or indirect Microbially Influenced Corrosion (MIC). One approach to reduce and/or remediate MIC is the application of microbicides to affected assets such as storage tanks, pipelines, heat exchangers and pumps. The objective of this paper is to generate efficacy data for biocidal formulations against corrosion-associated biofilms grown under anoxic and flowing conditions, which is difficult to obtain due to the distinct nature of biofilms and growth conditions. This data can be more representative when mimicking petroleum and water transporting pipelines. Thus, to facilitate the testing and comparison of products that successfully attenuate MIC under field-relevant conditions, a method that allows consistent corrosion measurements to be made, for corroding biofilms grown on steel surfaces under flowing and anoxic conditions, has been developed. This method utilizes microorganisms that were enriched on carbon steel from a North Sea sediment sample that, when grown in recirculating flow circuits, can generate corrosion rates of up to 65 mpy after four weeks of growth. The samples taken for the enrichment of corroding cultures came from a low tide anoxic sediment sample (black sand). In this presentation and paper, this method and its application to the benchmarking of field-relevant biocidal chemistries in MIC control experiments are described. Attention will be given to the reproducibility of the method as well. Distinct differences can be observed in biocidal performance against biofilms developed on metal surfaces.
The attachment of marine fouling organisms is harmful to any marine structure such as ship hulls, fishing nets, jetties and platforms. Marine antifouling coating is still the widely commercial used solution for marine antifouling in shipping industry. It is necessary to evaluate the antimicrobial and antifouling performances of marine antifouling coating before formal use. Assessment methods of antimicrobial and antifouling performances are investigated in this study. Based on the antifouling mechanism, flat colony counting test, crystal violet staining test, diatoms static fouling test and diatoms dynamic fouling test are chosen for the laboratory test. With reference to some standards on shallow submerging test for marine antifouling panel, the deficiencies of the current evaluation method are discussed and the corresponding solution is then proposed. The appropriate proportion of the evaluation scale is divided according to the different influences on the antifouling property of the biofouling, and the monomer fouling is selected as the main evaluation scale. A novel calculation method of Fouling Resistance can be proposed and compared with ASTM and SAC standard. An effective assessment system for antimicrobial and antifouling performance of marine antifouling coating is proposed and validated by cases.
Biofouling describes the settlement and the accumulation of marine organisms, such as bacteria, diatom, barnacle and oyster, on the structures immersed in seawater which can cause a variety of problems. On ship hull, it can increase the hydrodynamic drag, lower the maneuverability of the vessel and increase the fuel consumption. This causes increased costs within the shipping industry through the increased use of manpower, fuel, material and dry dock time (Muller, Wang, Proksch, Perry, Osinga, Garderes, and Schroder, 2013; Yebra, Kiil, and Dam-Johansen, 2004). Many studies have been carried out around biofouling, and there are various antifouling methods and antifouling patents, but antifouling coating is the most widely used antifouling method (Amara, Miled, Slama, and Ladhari, 2018; Chambers, Stokes, Walsh, and Wood, 2006).
The technology consists on using microorganisms in biofilm in order to remove the toxicity of produced water, at low cost with a low footprint for offshore sites.
For a long time, the concentration of oil-in-water was the unique specification for water disposal into the sea. With a new European regulation and worldwide evolution, the environmental performance includes also the demonstration of toxicity removal close to the production site.
Worldwide, the quantity of produced water is increasing continuously year after year of production. Even if produced water reinjection is the favorite option within TOTAL, a large part of produced water is still released into the sea.
The technologies, currently implemented offshore, are not always sufficient to comply with this regulatory evolution: suspended hydrocarbons are well treated but dissolved compounds are not. Biological treatment can reduce the toxicity of wastewater as it will biodegrade organic pollution such as phenols, mono or Poly Aromatic Hydrocarbons. But the size of conventional biotreatment equipments is not compatible with the offshore constraints.
Among biotreatment systems, a technology called MBBR (Moving Bed Biofilm Reactor) which involves bacteria organized in biofilm attached to supports, demonstrated a strong robustness compared to conventional activated sludge. The size reduction of equipments induced by MBBR has never been evaluated on saline produced water.
Lab trials demonstrated the potential of biodegradation for saline water. The team wanted to reduce the size of equipments by dividing by at least 20 the residence time of the bioreactor.
Lab experiments with supported biomass demonstrated the efficiency of the system on produced water containing up to 15% of salinity. The ecotoxicity measured on sensitive species was removed and the concentration of hydrocarbons was drastically reduced (<3 mg/L).
The experimental pilot (0.5-4 m3/h) was operated for 10 months until May 2017 in South West of France on a production site. With only 30 min residence time, the toxicity was reduced by 85% where usual biotreatments require 24 hours of residence time.
The pilot is equipped with a final step including membrane filtration with reverse osmosis in order to demonstrate the feasibility of desalination for water reuse.
The technology is the first compact biological treatment. Stakes are huge. For a flowrate 20000 bpd, the investment cost for a TOTAL site offshore is today close to 40M$. This cost is estimated at 10M$, the footprint is divided by 3 and the weight reduced by 2 compared to extraction process. It is now possible to implement a biotreatment offshore.
Broussard, Zach (Nalco Champion, an Ecolab Company) | Tidwell, Timothy J. (Nalco Champion, an Ecolab Company) | De Paula, Renato (Nalco Champion, an Ecolab Company) | Keasler, Victor (Nalco Champion, an Ecolab Company)
An oil transmission pipeline in the Eagle Ford area was being treated with 150ppm of active biocide based on a five percent water hold up but good control of the microbial population was not being maintained based on cATP data obtained from swabbing coupons within the system. Based on field data and recommendations, 3750ppm of active biocide was chosen to replace the incumbent biocide treatment and a sessile kill study was requested to validate the treatment plan before being implemented in the field. Subsequent sessile kill studies and biofilm regrowth studies indicated that an initial biocide treatment was not successful in killing or removing biofilm but that a second biocide treatment, performed two weeks after the initial treatment, was much more effective. Several mechanisms of biofilm resistance to biocide treatments are discussed to help understand the efficacy of this biocide treatment plan.
Microbial contamination of oilfield pipelines can lead to microbiologically influenced corrosion (MIC) and other issues including hydrogen sulfide (H2S) souring and biofouling. A typical program used to mitigate microbial populations and their resulting issues often includes a biocide application either through batch injection or continuous injection, with the latter typically not being recommended. Typical batch injection concentrations range between 100-1000ppm (μL/L). It is of the opinion of the authors that to be considered a successful treatment, batch biocide treatments must reduce the microbial population by approximately 99% of planktonic cells and 90% of sessile cells. However, because biofilms have been shown to be the primary cause of MIC and can be much harder to treat than planktonic microorganisms, biocide efficacy against sessile populations should be the deciding factor when choosing a biocide treatment strategy.1,7
It is well known that biofilms often exhibit decreased susceptibility to antimicrobial agents and mechanisms of this decreased susceptibility have been well studied and reviewed. These mechanisms include slowed cellular growth, adaptive stress responses, horizontal gene transfer, presence of tolerant persister cells, and efflux of antimicrobials (1,2,3) Additionally, the extracellular polysaccharide (EPS) matrix, made up of biopolymers secreted by microbes, provides a biofilm’s first line of defense against biocides and other anti-microbials by excluding or preventing the penetration of these molecules into the biofilm.(3,4,5) Due to the decreased susceptibility caused by these mechanisms, it is important to validate biocide treatments against biofilms representative of the system to be treated.
Wolodko, John (University of Alberta) | Haile, Tesfaalem (Innotech Alberta) | Khan, Faisal (Memorial University of Newfoundland) | Taylor, Christopher (DNV-GL) | Eckert, Richard (DNV-GL) | Hashemi, Seyed Javad (Memorial University of Newfoundland) | Ramirez, Andrea Marciales (Innotech Alberta) | Skovhus, Torben Lund (VIA University College)
Microbiologically Influenced Corrosion (MIC) is a complex form of materials degradation caused by the biological activity of microorganisms such as bacteria, archaea and fungi. It is typically characterized by the presence of microbiological populations within a biofilm or semi-solid deposit resulting in localized and accelerated corrosion. While MIC has been actively studied for decades, there is still a significant gap in the ability to accurately predict MIC rates. This is due, in part, to a limited understanding of all the microbiological communities involved in MIC, and the complexity of biological, chemical and operational parameters responsible for MIC. For the oil and gas sector, the threat of MIC can be particularly challenging since it can affect a wide range of operations including upstream production and processing facilities (onshore and offshore), mid-stream and transmission pipelines and water systems. Compared to other corrosion threats, the detection of MIC is typically reactive rather than pro-active (i.e., MIC is difficult to predict and is most often detected after an inspection or failure). As such, there is a continued demand for validated predictive tools to assist in managing the threat of MIC. The objective of this paper is to provide a review of various models and methods that have been developed and applied by both researchers and industry professionals to better understand and predict MIC. This includes a number of phenomenological and mechanistic models that have been developed by the research community to help explain specific MIC mechanisms or predict corrosion rates, and a number of risk-based models applied by industry to screen and rank the potential of MIC threats. The advantages and disadvantages of each modeling approach are summarized, along with a discussion of new potential methods such as molecular modeling, risk based inspection (RBI) and Integrated Computational Materials Engineering (ICME).
Microbiologically Influenced Corrosion (MIC) is a problematic and common form of corrosion caused by biological activity of various microorganisms. MIC is a significant threat in the oil and gas sector, and has been estimated to account for almost 40% of internal and 20-30% of external corrosion problems in pipelines.1 The prediction of MIC is a challenging area due, in part, to the complex interaction between the biological, chemical and physical variables involved, and due to a limited understanding of microbiological communities, their interactions and the mechanisms affecting corrosion.
Liu, Jialin (Ohio University) | Dou, Wenwen (Ohio University) | Jia, Ru (Ohio University) | Li, Xiaogang (University of Science and Technology) | Kumseranee, Sith (PTTEP) | Punpruk, Suchada (PTTEP) | Gu, Tingyue (Ohio University)
This study demonstrates that the mechanisms of microbiologically influenced corrosion (MIC) by Desulfovibrio vulgaris, a sulfate reducing bacterium (SRB), against X65 carbon steel and pure copper belong to two different types of MIC. Type I MIC involves extracellular electron transfer across cell walls of sessile cells in biofilms. This type of MIC is also called extracellular electron transfer MIC (EET-MIC). Type II MIC, also known as metabolite MIC (M-MIC), is caused by secreted corrosive metabolites that are more concentrated locally under a biofilm. The corrosive metabolites secreted by planktonic cells can also contribute to Type II MIC. The metabolites oxidize metals extracellularly without biocatalysis or EET. Experimental data in this work show that 20 ppm (w/w) riboflavin, a universal electron mediator, did not enhance sessile cell growth, but it accelerated EET-MIC by D. vulgaris in the ATCC † 1249 medium against X65 carbon steel with a 90% increase in weight loss and a 284% increase in the average maximum pit depth. However, 20 ppm riboflavin did not increase copper MIC, because copper MIC by SRB was due to secreted metabolites (i.e., M-MIC) rather than the direct result of sulfate reduction. This work also shows that copper MIC weight loss caused by the SRB was at least one order of magnitude higher than that of X65 carbon steel even though the SRB sessile cell count on copper was 10 times lower.
The awareness of MIC increased significantly in the past decade in many fields such as the oil and gas industry, water utilities, and the biomedical implant industry.1-3 Sulfate is a ubiquitous oxidant (electron acceptor) in seawater, brackish water and even in human saliva. Thus, SRB are often found in anaerobic environments because they can utilize this readily available oxidant.4,5 Most environments in the oil and gas industry such as reservoirs and oil transport pipelines are strictly anaerobic.6 In systems that are open to the air, SRB may grow underneath aerobic biofilms such as an iron oxidizing bacterium biofilm.7,8 Although SRB are often blamed for MIC in various settings, nitrate reducing bacteria and acid producing bacteria are shown to be corrosive as well.9-11
Lei, Ma (Tarim Oilfiled Company) | Junfeng, Xie (Tarim Oilfiled Company) | MaoXian, Xiong (Tarim Oilfiled Company) | Yan, Li (Tarim Oilfiled Company) | Mifeng, Zhao (Tarim Oilfiled Company) | Hua, Wang (Tarim Oilfiled Company)
API-RP38 culture medium was used to culture sulfate SRB isolated from an oilfield wastewater sample. SRB test bottle method was used to verify bacterial activity, and SEM was employed for identifying the microbial morphology. Corrosion behaviors were studied via weight loss methods and electrochemical tests including polarization curve and EIS measurements. The results of corrosion weight loss show that the corrosion rate of carbon steel was accelerated significantly after the inoculation of SRB, characterized by pitting corrosion. The real oilfield conditions with high content of H2S and high salinity were simulated for tests and the results indicate that severe pitting corrosion also took place under the conditions of SRB which survived in the unfavorable environments. The results of polarization curves show that, in H2S environments with the existence of SRB, the corrosion potential of carbon steel negatively shifted and the corrosion current density increased as the passage of testing time. However, without SRB, the corrosion potential shifted positively and the corrosion current density decreased due to the protection of uniform corrosion product film. EIS results show that, with the existence of SRB, both the corrosion scale impedance and charge transfer impedance decreased as the passage of testing time. As the time lengthened, this tendency turned more apparent. While under the sterilized conditions, both the corrosion scale impedance and charge transfer impedance increased as the testing time elapsed.
About 80% of the underground metal damages are caused by microbiologically-induced corrosion (MIC). Sulfate-reducing bacteria (SRB) are found the main microbes that cause MIC.1,2 As anaerobic species, SRB feed on organic matters and can metabolically reduce sulfate to sulfide. Widely existing in the soil, sea, river, underground pipelines, oil and gas wells, etc. SRB induce the corrosion of metallic structures, resulting in overwhelming economic losses.3-5 It has been found that, under anaerobic conditions, SRB thrive and produce mucus, which contributes to the formation of scale, blocking water injection pipelines. In turn, the sediment scales in the pipeline are favorable for the reproduction of SRB, often resulting in severe localized corrosion on the pipe surfaces and further pitting perforation of the pipe walls.6-8 In US, statistics indicate that more than 77% of oil well corrosion failures are related to SRB, dominantly characterized by pitting.9 Different mechanisms have been proposed to explain the reason for corrosion induced or accelerated by SRB, including, for instance, cathode depolarization theory and localized corrosion cell theory.10,11 However, SRB corrosion has not yet been studied in depth in certain special environments. Some researchers have shown that SRB cannot survive in environments with high concentration of H2S or high salinity.12-14 however, it is not rare that severe corrosion phenomena caused by SRB have been observed under such conditions in oil and gas gathering pipelines and well tubings. Under such a background, this study focuses on the effects of SRB on pitting corrosion behavior of carbon steel in H2S environment.
De-Abreu, Yolanda (Nalco Champion) | Balasubramanian, Ramakrishnan (Nalco Champion) | Zhang, Yingrui (Nalco Champion) | Valenstein, Justin (Ecolab Inc.) | Li, Junzhong (Ecolab Inc.) | Staub, Richard (Ecolab Inc.) | Lange, Steven (Ecolab Inc.)
Peracids are multifunctional chemistries that are an equilibrium mix between an organic acid and peroxide. Peracids are widely used as biocides in oil and gas, food and beverage, health care and other industries. In addition to its use as a biocide, peracids are often used for iron sulfide scale dissolution and hydrogen sulfide control.
The performance of peracids as a biocide is dependent on many factors. These factors include the presence of other oxidizable species, temperatures, salinity as well as the metallurgy of the treatment setup. Compatibilities of SS430 and SS304 alloys were evaluated with high peroxide and low peroxide formulations of peracetic acid solutions in the presence of chlorides (0.9% weight). Effect of biofilm on the alloys was evaluated prior and post peracetic acid treatments. Anodic cyclic polarization, electrochemical impedance spectroscopy and surface analysis were used to evaluate the factors that affect the corrosion on metallurgies under treatment conditions. The results suggest that irrespective of the metallurgy, peroxide concentrations in peracid formulations is a key parameter that must be accounted for to determine corrosion potential and provide a strategy for application of these products on different metallurgies.
Biocides also known as antimicrobials are often used to control problematic microorganisms in the oil and gas industry. Uncontrolled microbial populations can cause severe asset integrity and safety issues including fouling and release of H2S. 1,2
Efficacy testing of antimicrobial products involves two types of microbial kill studies; planktonic and sessile tests. Planktonic tests are performed either using a native set of microorganisms or a test microorganism (like Pseudomonas aeruginosa) suspended in a test fluid. For sessile testing, microorganisms are grown as a biofilm on a coupon, typically in a bioreactor. In either of these cases, the performance of a biocide is tested using a variety of techniques including ATP quantitation, confocal microscopy as well as using outdated techniques like bug bottles.3
Deposits on surfaces in water - bearing systems, also known as ”fouling,” can lead to substantial losses in the performance of industrial processes as well as a decrease in product quality and asset life. Early detection and reduction of such deposits can, to a considerable extent, avoid such losses. However, most of the surfaces that become fouled, for example, in process water transport pipes, membrane systems, power plants, food and beverage industries to name a few, are difficult to access and the analysis of the water phase do not reveal the extent of the deposits. Furthermore, it is of interest to distinguish between microbiological and nonmicrobiological deposits. Although they occur together, different counter measures are necessary. Therefore, sensors are required that indicate the development of surface fouling in real time, non-destructively, in situ and can discriminate between abiotic and biotic based deposits. A new and novel sensor has been developed that provides said discriminate detection by utilizing conventional heat transfer reduction sensory coupled with ultrasonic detection of materials on the same surface concurrently. The technical aspects of the design, operation, and application will be discussed in the paper. Real time graphical detection followed by automated reduction control runs will also be presented as well as revealing if the deposit is biotic or abiotic.
One of the main causes of performance loss, quality and runnability problems in industrial systems is related to contaminants and deposits. These deposits are composed of inorganic, organic and / or microbial matter, respectively. Most of the deposits contain various or even all types of these contaminants and form complex matrices. Of these, microbiological contaminations, also named biofouling, are one of the biggest issues and risks in water bearing industrial systems. They cannot only cause deposits that impact the function and efficiency of the systems. They often are the cause for health risks (e.g., Legionella). Fouling can be generalized into four forms, inorganic, suspended solids, organic, and microbiological. Of these forms of fouling, it is only inorganic crystallization fouling that does not lead to the worst form of corrosion, namely localized. This type of corrosion eventually transitions into high pitting penetration rates that drastically reduce the asset life.
The majority of the fouling which occurs in aqueous systems are detected indirectly by means of reduced process side throughput, increased time to get to operating temperature and or pressure, pressure drop, approach temperature increase, or the use of extensive instrumentation to calculate ”at that time” heat exchange U-coefficients and or cleanliness factors. Under certain circumstances, some of these methods are not sufficiently accurate unless normalized. Or the measurements taken have not been corrected for cooling water or process flow changes, shear stress change and bulk cooling water change or surface temperature changes. There may be a large lag time to foulant detection which can lead to foulant aging and dehydration to a point of being irreversible fouled, whereby chemistry and chemical adjustment in the water side environment would not provide cleansing of the surface and maintain a clean state. An example would be the comparative time for a side stream annular heat transfer test section to detect fouling of a well instrumented utility surface condenser, wherein they were both operated at the same surface temperature and shear stress (velocity corrected for the geometry) on the same cooling water.4 The steam surface condenser heat transfer surface area for 175 MW would be 150,000 ft2 (13,935 × 106 mm2) would require a large quantity of foulant coverage to be detected compared to the annular test section which has 0.05 ft2 (4645 mm2) of foulant detection surface.