ABSTRACT There is a corrosion phenomenon, Microbiologically Influenced Corrosion (MIC), that has been misunderstood and misdiagnosed in the electrical submersible artificial lift industry for years. MIC can be caused by sulfate reducing bacteria (SRB), as well as, other anaerobic and aerobic bacteria. This phenomenon has been known by some in the industry, but it has been my experience as a Corrosion Chemist/Forensic Engineer that this corrosion phenomenon is not well understood in the "Oil Patch". Therefore, this phenomenon may be overlooked as a corrosion mechanism. A better understanding of this issue could reduce the corrosion damage and the cost associated with a misdiagnosis. In an effort to further the understanding of"microbiologically influenced corrosion", as it is manifested in the artificial lift industry, this paper is a presentation of MIC experienced by a number of oil companies around the world. This corrosion phenomenon may be misdiagnosed in the entire field
INTRODUCTION There are a number of bacterial species present naturally in downhole waters and in introduced (injection) waters in the "oil patch". The American Petroleum Institute (API) recognizes a number of microorganisms present in petroleum production and transportation. This paper will focus on four bacteria associated with petroleum production. The four types seen most often in electrical submersible pumping systems producing oil are anaerobic sulfate reducing bacteria (SRB), anaerobic acid- producing bacteria (APB), aerobic acid-producing bacteria (APB), and slime forming bacteria. The slime forming bacteria cause more issues with downhole formation and surface equipment plugging than centrifugal pump stage plugging. However, though rare, there is a chance that this type of bacteria may plug the hydraulic balance holes of the pump impeller causing the hydraulics of the stage to change; causing operation issues but not necessarily corrosion.
Focus on the four bacterial types mentioned above is not intended to ignore iron-oxidizing bacteria. The intent of this paper is not to say that the iron-oxidizing bacteria do not play an indirect, and at times a direct, role in supporting or directly causing corrosion in artificial lift production. However, there are a number of papers in the literature dealing with iron-oxidizing bacteria in petroleum production. Our intention is to explore corrosion associated with the four bacterial types mentioned above. This paper will focus on the sulfate reducing bacteria (SRB), aerobic acid-producing bacteria (APB) and anaerobic acid-producing bacteria (APB). This paper will present examples from four areas on the world, North America including a southwestern United States application, Latin America, West Africa, and the Middle East.
ABSTRACT Pipeline operators are today faced with an increasing number of challenges. In addition to implementing more rigorous pipeline integrity programs, integration of pipeline data has now become a major concern.
Through the use of a highly accurate inertial navigation system (INS) on board an In Line Inspection (ILI) smart pig, longitude, latitude and elevation coordinates can now be provided along the pipeline every tenth of an inch. This information provides the most accurate reference for integrating and relating pipeline data in a comprehensive manner. One of the most significant benefits to the operator is an absolute reference for integration of legacy and current pipeline data.
This paper describes the processes involved in providing a data integration service to a major pipeline operator in the continental United States. Additionally, this paper shall focus on the benefits of combining pipeline-mapping services with an ILI smart pig survey.
INTRODUCTION Today pipeline operators are facing an aging pipeline infrastructure, more stringent regulatory practices and, due to technological advancements, an ever-increasing amount of data that must be analyzed in a coherent manner. In order to meet these challenges, budget dollars must be spent in a way that addresses all pipeline integrity concerns. Additionally, budget spending must be cost-effective and must target products and services offering innovation and efficiency.
The purpose of this paper is to describe how an effective implementation of Geographical Information System (GIS) technology, TruView® GIS(1) tightly coupled with ILI analysis, can be used as a data integration platform for enhanced decision support for pipeline integrity management programs (IMP). Through comprehensive analytical and visual tools and accurate data integration, large diverse and complimentary data sets can be analyzed for making timely, informed, and economic decisions for risk assessment.
This paper describes the components and techniques used for this method of data retrieval and accurate integration. It also highlights new regulatory requirements for data integration and integrity management, and finally, describes two case studies involving In-Line Inspection and subsequent GIS implementation for pipelines located in the continental United States.
ABSTRACT Small fragments of the hydrocoral, Millepora dichotoma, were glued to PVC racks containing three different types of metals. The following groups of metals were deployed: electrochemically passive alloys - UNS $30403, UNS $31603, UNS $31254, UNS R50400, UNS R52400, UNS R53400 and UNS N10276; electrochemically active metal with no harmful biological effect- St-37 mild steel; metal alloys with biocidic effect - commercial copper and casting brass 70 Cu 30 Zn. The samples were immersed in a coral reef environment, at 6 meters depth for a period of 3 months, between May-August 2000. An adhesive two-dimensional growth of the M. dichotoma encrustation layer on the metal surface was clearly observed in all the electrochemically passive metals. No two-dimensional development of the hydrocoral was observed on the mild steel. The tips attached to the plates of commercial copper and casting brass 70 Cu 30 Zn, were damaged and died within three weeks.
INTRODUCTION Prolonged immersion of metallic substrates in seawater exposes those materials to the action of high ionic concentrations and elevated electrical conductivity. The resultant corrosion is further aggravated by the presence of marine organism. The newly settled epibiotic biofilm may firstly alter the electrochemical environment of the metallic surface, by creating the possibility crevice conditions, that influence the oxidation-reduction potential, through a mechanism related to microbiological induced corrosion a. In tropical oceans, deposition of a biofilm is followed by the settlement of sessile organisms such as algae, tunieates, corals, sponges and hydrozoans. Such environments contain a rich diversity of micro and macro organisms, often acting in consort, that is, with one species creating environmental conditions in which another can flourish and grow 2.
The hydrocoral Millepora dichotoma is an important contributor to the foundation of coral reefs in tropical oceans. Like reef-building corals, M. dichotoma is a sessile colony composed of living polyps which maintain and precipitate a porous calcareous skeleton, composed of CaCO3, in the crystalline form of aragonite 3. The polyps are located in special cavities in the skeleton, and are connected by a continuous tissue 4. In the initial stage of its skeletal formation, the hydraeoral deposits adherent encrustation layers, which serve as a base for the branched growing colony. The two-dimensional growth form is obtained, depending of the substrate characteristics and the physical cues along the reef profile. The deposition of this primary growth morphotype is later followed by three-dimensional growth of the colony 5. Elements and compounds to which the M. dichotoma is exposed become entrapped within the aragonite during deposition. Such elements can be provided either from the water or from the solid substrate 6'7. Interaction between M. dichotoma and an A1 6061 metal surface was previously reported 8. Colossal two-dimensional growth of the M. dichotoma was observed and related to the local pH conditions near the surface. The A1 alloy represents a metastable metallic surface in the coral reef environment. The present study focuses on the interactions between three types of metallic substrates and the hydrocoral M. dichotoma: electrochemical passive metals; electrochemically active metal with no harmful biological effect; metals with biocidic effect.
ABSTRACT This study evaluated the technical feasibility of applying an optimized combination of cathodic polarization (CP) and inorganic Zn coating, the two, common corrosion protection methods employed for marine structures. As an initial step to achieve this goal, batches of inorganic Zn coatings with various thickness were formed on A36 Gr. steel plates. The effects of cathodic polarization parameters, such as CP current density, potential were evaluated to establish the optimum combination to provide better corrosion resistance of the inorganic Zn coated steel plate in natural seawater. Optimum number and arrangement of CP anodes for 3-dimensional mock-up structure of ballast tank were also evaluated by using FEM analysis of potential distribution under CP, and the result was fairly consistent with the experimental data obtained from tests made on the inner surface of a box-type, mock-up structure.
It's suggested that thicker inorganic Zn coating (about 40gm) is desirable than the conventional "shop primer" (about 101am), whereas the current density of 0.5~1 A/m 2 for CP is necessary to form calcareous deposit on the inorganic Zn coating to ensure continuous corrosion protection. Evaluation of the proposed method's protective properties by using electrochemical techniques suggested that the combination of CP and inorganic Zn coating can be as effective as tar-epoxy in certain application areas.
INTRODUCTION High-performance epoxy coating systems are generally known to protect seawater ballast tanks for at least 10 years with 2% coating area failure at five years and 5 to 10% failure at 10 years before the coatings are completely replaced . Over the years, field experiences on the corrosion resistance of epoxy coated ship ballast tank revealed that certain localized areas, such as corner and edge parts and the weld bead of joints, were especially susceptible to earlier corrosion due to irregularities of epoxy coatings. As a result, these areas subjected to accelerated general corrosion and pitting require frequem maintenance and repair of the epoxy coating system [2,3]. Another concern in the corrosion protection by ship ballast tank coating is the recent trend to reduce use of toxic paints, and to employ alternative approaches to develop more "environment-friendly" corrosion protection methods. Recently, there were studies to form calcareous deposits on steel surface immersed in seawater, such as ship ballast tanks, by using electrochemical methods, i. e. cathodic polarization via impressed current or sacrificial anodes [3-5].
Recemly, a series of field tests were conducted for using calcareous deposition as a corrosion protection method to investigate its effectiveness for the protection of actual ship ballast tanks . Since the calcareous deposition is made of cations (Mg +2, Ca +2) naturally presented in seawater, it obviously has several advantages over the conventional epoxy coating. For example, calcareous deposit is less sensitive to pretreatment of the steel surface, and it can have a "self-healing" function with proper placement of sacrificial anodes. On the other hand, a previous study by the authors showed that the calcareous deposition was more effective with the pre-existing primer coating on the steel surface than the shot-blasted condition in terms of the steel surface pretreatmem . Moreover, it has been also recognized that an anti-fouling effect as well as an anti-corrosion property could be imparted by the electrochemical cathodic protection technique coupled with an inorganic Zn-primer coating. Thus, in this study, the technical feasibility of the combined electrochemical cathodic protection with Zn-primer coating was investigated.
ABSTRACT A new strategy has been applied successfully to pre-select corrosion inhibitors and short-list products to be considered by the operators. In particular the more comprehensive evaluation of the partitioning properties of the chemicals has improved the chances of successful application in the field. Some of these products have already been tested in the field to verify their effectiveness. The availability of suitable field corrosivity and monitoring methods has been a key success factor.
INTRODUCTION Corrosion inhibition is one of the most commonly used methods for controlling corrosion of carbon steel equipment in oil and gas production, transportation, and processing. In recent years corrosion inhibition has become more and more common in our operations, even to protect carbon steel in relatively aggressive conditions 1. A large number of commercial corrosion inhibitors is available, and new products are being continuously introduced to handle more corrosive conditions and to meet more stringent environmental regulations.
Our laboratories have been involved repeatedly in selecting the best product from a long list of candidate products provided by the suppliers. The test procedures are described in our externally available report "Corrosion inhibitor testing and selection guidelines ''2. In reference 1, a total of 33 products from 10 suppliers were submitted for consideration for a pipeline project. This example is typical of the challenges facing the corrosion engineer who has to make a well-supported recommendation in a short time and with limited resources.
Unfortunately, the results of one project could rarely be used for another, because the tests were always carried out at very specific conditions. Hence, in spite of the commonality of the objectives of the test programs, the time and money invested was paid back by only one project. The time required to develop a shortlist of products for a specific application was often excessive, and final verification tests, e.g. flow loop tests to verify shear resistance or compatibility tests with other chemicals present in the system put the project schedule at risk.
In our role as consultants, we have to react quickly and keep an eye on future developments. Obviously, the above-described ad hoc approach does not allow us to fulfil this function very efficiently. In particular the need to stimulate the development of environmentally friendly ("green") products and the trend to apply inhibition in more aggressive conditions in terms of higher temperatures and shear will be key factors. To this end, it was decided in 1999 to develop a set of procedures to pre- select corrosion inhibitors for Standardized conditions, which are described in this paper. Additional more specific laboratory tests and field verification tests, recommended for critical applications, are described elsewhere.
ABSTRACT This is a report of exposure of various metal tubing to oceanfront launch environment. The objective is to examine various types of corrosion-resistant tubing for Space Shuttle launch sites. The metals were stainless steels (austenitic, low-carbon, Mo-alloy, superaustenitic, duplex, and superferritic), Ni-Cr-Mo alloy, Ni-Mo-Cr-Fe-W alloy, and austenitic Ni-base superalloy.
INTRODUCTION The objective of this project is to test and examine various types of corrosion-resistant tubing for use at Space Shuttle launch sites. The existing 304-stainless-steel tubing at Launch Complex 39 (LC-39) launch pads is susceptible to pitting corrosion. This pitting corrosion can cause cracking and rupture of both high-pressure gas and fluid systems. Failures of these systems can affect the safety of Shuttle launches as well as pose life-threatening conditions to personnel in the immediate vicinity. The use of a new tubing alloy for launch pad applications would greatly reduce the probability of failure, improve safety, lessen maintenance costs, and reduce downtime losses.
ABSTRACT Sea water injection systems have traditionally been treated with biocide to inhibit growth of sulfate reducing bacteria (SRB) and reduce microbial induced corrosion (MIC). Laboratory experiments have shown that nitrate treatment can be an effective alternative to biocide treatment to reduce the number and activity of SRB. Based on such experiments the decision was made to implement nitrate treatment to the injection water on the oil platform Veslefrikk (North Sea).
Addition of low dose of nitrate resulted in a decrease in the amount and activity of SRB in the water injection system. After 4 months nitrate addition, the activity of SRB in biofilm samples were strongly reduced. Corresponding to the decrease in SRB, an enrichment of nitrate reducing bacteria (NRB) was observed. After 32 months nitrate treatment SRB numbers were reduced 20 000 fold and SRB activity 50 fold. Corrosion measurements on metal coupons showed a decrease in weight loss from 0.7 mm/year to 0.2 mm/year. The results show that nitrate treatment can efficiently inhibit growth of SRB and control MIC in C-steel top side sea water injection sy stems.
As opposed to the use of biocides such as glutaraldehyde, nitrate does not represent health hazard to platform personnel. Glutaraldehyde is classified as "Toxic" and may cause allergy to personnel handling the chemical. Inorganic nitrate salts have no negative environmental implications.
INTRODUCTION At Veslefrikk sea water is injected into the oil reservoir in order to maintain reservoir pressure. In this process oxygen is removed in an attempt to minimise corrosion. This produces ananoxic environment that due to access of sulfate selects towards sulfate reducing bacteria (SRB). By anaerobe respiration with sulfate SRB produce the highly toxic and corrosive gas hydrogen sulfide (H2S). The growth of SRB in injection pipelines causes corrosion of iron and steel alloys.
Laboratory experiments with oil reservoir model column have shown that injection of nitrate inhibits sulfide production 1. Nitrate reducing bacteria (NRB) reduce nitrate to N2, where the first step in the reaction is reduction of nitrate to nitrite. SRB is believed to be inhibited by nitrite and an increased redox potential due to chemical oxidation of sulfide by nitrite.
ABSTRACT Early stage biofouling phenomena on titanium alloys - electrochemical passive metals, was tested in the coral reef environment in the Red Sea, Aquaba gulf at the shores of Eilat. Titanium alloys: UNSR50400, UNSR52400 and UNSR53400 were exposed to the reef environment at a depth of 6 m. for a month, during December 2000. Settlements of vireos marine organisms were observed on all the exposed samples. Potentiodynamic polarization measurements show that after exposure to the environment samples exhibit improved passivation characteristic. The passivatiom current density decreased in about two orders of magnitude in all the samples tested. UNSR52400 exhibit an effective cathodic depolarization after exposure to the coral reef environment that results in a higher corrosion potential. Microscopic observations reveal various chromista settlements especially diatoms. It is suggested that during the early stages of exposure pH conditions, on the surface of the Ti alloys encourage settlements of organisms that deposit silica skeleton, such as diatoms.
INTRODUCTION Titanium alloys in seawater are passive and are most likely not to suffer from any form of corrosion 1, yet they are suffer from to biofouling like other passive alloys that are used in sea applications. Exposure to the marine environment the Ti alloys can provide substrates for reef-building organisms such as corals, bryozoa, and sponges, which precipitate CaCO3 skeletons, in the form of aragonite or calcite 2 and different sorts of algae. Among the different organisms there is a large group of silica - amorphous SiO2 skeleton depositors named chromista. Almost all of the species of the chromista are photosynthetic and aquatic. All of the members of the chromista share the possession of the form of chlorophyll known, as chlorophyll c. Chlorophyll c does not occur in plants or the "green algae". The various groups of the chromista vary in shape and size. For example, Diatoms can range from a few microns up to lmm 3-4.
ABSTRACT Maintenance of a pipeline facility will invariably involve the repair of imperfection, anomalies or defects that are found in the course of routine inspection. The codes and regulations governing pipelines offer several options for carrying out these repairs. In some cases, the repair option will be defect specific but in others, the operator will be expected to choose a repair technique based on individual assessment. Pipeline repair alternatives allowed by various codes are reviewed. Special attention is placed on the new composite repairs along with the mechanical properties and design prerequisites that ensure this technology is effective. Different composite architectures and installation methods are compared. The process of selecting a repair technique based on effectiveness, safety, response and economics are outlined. Supplemental information is provided that gives detail on how to use composite repairs as a means of calibrating and qualifying future In-Line-Inspections with Magnetic Flux Leakage inspection tools.
INTRODUCTION Pipelines are critical to the world economy and will be increasingly used as the preferred method to transport raw and refined hydrocarbons, chemicals, water and natural gas. The difficulties in acquiring new right-of-way and the cost of building new pipelines put additional focus on maintaining the existing facilities and maximizing its performance. Maintenance has always been a critical issue but has taken on an even greater role in today's competitive environment. 1 Each pipeline company is expected to have: a) Written detailed plans and training programs for employees covering operation and maintenance of the pipeline facility during normal operation in accordance with applicable codes. b) Corrosion control on new and existing systems. c) Emergency Plans for implementation in the event of a system failure, accident or other emergency. d) A plan for reviewing changes in conditions affecting integrity and safety of the piping system. e) Establish liaison with local authorities to prevent accidents caused by excavators. f) Procedures to investigate failures and accidents to determine root cause. g) Maintain necessary maps and records and monitor construction activity around or near the facility. h) Procedures for abandoning facilities. i) Specific plans for pipe sections that represent increased hazard to the public. Pipeline Companies are expected to operate and maintain the system in conformance to these plans and to modify or revise the procedures based on experience or as exposure of the system to the public or changes in operating conditions require.1 Maintenance requires inspection of the facility and the replacement or repair of defects or imperfections that could jeopardize the facility if left unchecked. The inspection task is generally done by one of several Direct Assessment techniques or In-Line-Inspection. The repair task involves choices and the operator must choose carefully to ensure effectiveness and permanency at a reasonable cost.
ABSTRACT Composite materials are utilized in military applications for their unique physical and structural properties, but need to be properly incorporated into designs in order to avoid degradation due to corrosion. Many of the constituent materials used in composite material systems are compatible with mating metallic fasteners and components, while others require special features in order to isolate them and prevent galvanic corrosion. Corrosion concerns with these applications have traditionally been associated with aluminum fittings that are attached to a carbon/epoxy component, whereby a protective layer is necessary to prevent contact between the carbon fibers and the aluminum. More recent material systems, such as metal matrix composites, require corrosion control at the microscopic level to prevent galvanic corrosion between the reinforcement fibers or particles and the matrix materials, as well as other forms of corrosion. This paper is primarily a literature review that discusses the various methods employed to control corrosion associated with composite materials in military applications, recent efforts to improve the technology, and opportunities for future related initiatives.
INTRODUCTION Composite materials are used extensively in military applications due to various reasons including weight reduction, corrosion and wear resistance, erosion resistance, high-temperature performance, thermal and acoustical insulation, electrical performance and life cycle cost reductions. Military aircraft as well as ground vehicles and tactical weapons employ composite materials in order to provide better mobility due to weight reductions offered. Some applications require the low weight and high stiffness achievable only with the use of structural sandwich design approaches. Other applications involving missions in a highly corrosive environment require the use of composite materials in order to maintain system reliability at an affordable cost. The variety of options for materials and processes available to the designer mandate that an understanding of the operational environment, system-level performance including maintenance and repair, cost and ecological impact are taken into consideration early in the design phase.
The family of composite material systems has evolved to include not only polymer or organic matrix composites (OMCs), but also metal matrix composites (MMCs) and ceramic matrix composites (CMCs). It is assumed that the reader is familiar with the basics of composite material systems involving the combination of different constituent materials to establish an end product that exhibits superior properties to any of the constituents for the particular application. The composite material is generally comprised of constituent matrix and reinforcement materials. The matrix encompasses and provides stability to the reinforcement constituents, which are typically in the form of a fiber or particle. A well-known composite material for example is steel reinforced concrete, where the matrix is the neat concrete mix, reinforced by steel re-bar (fibers) and aggregate (particles).
As composite materials are utilized in high performance designs they are typically required to be assembled in a fashion that places them into contact with dissimilar materials with different electrochemical potential, resulting in the susceptibility to galvanic corrosion. This has often been the case for carbon reinforced OMCs assembled to aluminum alloy structures in airframe applications. The nobler carbon fiber acts as the cathode while the more active aluminum acts as the anode if they are attached and have continuity in the presence of an electrolyte. Thus the aluminum corrodes if not properly