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Lifecycle
ABSTRACT Hydraulic and chemical models of water distribution systems can be interfaced with on-line sensors to provide a highly accurate and up-to-the-minute description of system operation. Such models can be used for real-time monitoring and diagnostics. They can also be used to improve system operation, evaluate replacement or system expansion options, solve pressure/flow problems, and solve water quality problems. The installation of a real-time sensor-enabled water distribution system model at an Army installation will be described. Concepts for the use of dynamic utility system models as part of an overall virtual installation planning and operations tool will be discussed. INTRODUCTION The U. S. Army is investigating the use of sensor-enabled computer-based models to help improve the operation of potable water distribution systems at its installations. Just as in the private sector, facilities engineers on Army installations strive to meet customer demands for potable water in a reliable and safe manner. The water distribution system must fully support a diverse variety of missions including the rapid preparation and deployment of equipment and troops. System security and emergency preparedness are also critical to protect the lives and safety of soldiers and their families. The water system operator must be ready to detect and quickly respond to new conditions or situations as they arise. We often rely on the experience of the water system operator and engineer to solve problems or respond to new situations. Many experienced system operators sense how their water system operates, and intuitively predict how it will respond in various situations. Experience allows them to recognize when something is wrong with the system. The underlying obstacles to this approach arise when an unfamiliar or time-critical situation occurs. Without the understanding that is given by a calibrated and detailed system model, the operator must blindly execute a solution. Additionally, there are problems related to transfer or retirement of system experts prior to adequate training of a new system operator. Computer-based models provide site-specific, clear, and detailed insight into the operation of a water distribution system. They can be used to ensure adequate water supply, investigate possible solutions to problems, aid in emergency response, or optimize system performance. They can also be used to capture the institutional knowledge that tends to be lost when an experienced operator retires. There are several general types of water distribution system models. These are illustrated in Figure 1 and are pictured in order from least accurate and reliable on the left, to most accurate and reliable on the right. The steady state (static) computer model calculates system hydraulic parameters such as flow rate and pressure at a given moment in time. This type of model can be useful for the analysis of situations that do not involve timevarying behavior. The off-line dynamic model calculates system hydraulic parameters (just like the static model), but it takes into account the system?s time-dependant behavior. For example, consumer demands are allowed to vary with time; valves can be opened and closed; pumps will operate according to a specified set of rules; and water levels in the storage tanks will vary. Instead of representing the water system?s behavior at a given moment in time, the dynamic model typically simulates its expected behavior over a period of hours or days. Some dynamic models include the ability to simulate water chemistry at each location in the system as it varies with time. It is often difficult to calibrate off-line models such that they accurately
- Water & Waste Management > Water Management > Water Supplies & Services (1.00)
- Water & Waste Management > Water Management > Lifecycle > Storage/Transfer (1.00)
- Information Technology > Architecture > Real Time Systems (1.00)
- Information Technology > Modeling & Simulation (0.96)
- Information Technology > Communications > Networks (0.77)
ABSTRACT All people, both mission critical and the general population, are potential targets of aggressors using chemical, biological, and radiological (CBR) agents. The contamination or loss of safe potable water could potentially cause the greatest damage to human health and a major disruption to the lives of those dependent on it. Hence, potable water is the most significant of the utilities. CBR agent detection through the use of sensor blankets, identification using extensive databases, and elimination via countermeasures are of the utmost importance in securing the safety of our water supply. This article summarizes: CBR threats, design priorities for protection, treatment methods, and response strategies. It also summarizes recent research in development of new control systems and test apparatus to assist in modeling fate and transport of CBR agents. INTRODUCTION This paper provides information on the potential threat to a building?s potable water supplies from chemical, biological and radiological (CBR) agents that could be used as a weapon by a terrorist. Terrorists are most likely to use low-technology, or agents that are readily available. Waterborne CBR agents that a terrorist organization might have access to would be categorized as one of the following: liquid, particulate, dissolved vapor, or infectious cells and spores. The emphasis has been placed on assessment of potential CBR agent release tactics, identifying vulnerable locations in a water supply system where CBR agents might be released, and countermeasures to protect against the CBR threat. Building occupant vulnerability to waterborne contaminates is determined by the effectiveness of the water supply treatment contaminant removal system, distribution systems? external and internal physical barriers, internal building water treatment system, and security measures in preventing introduction of agents. Real-time or in-line sensors that have the ability to test for all potential chemical and biological agents are currently being developed, but not yet marketable. Further testing is needed to place these sensors on the market for public use. Radioactive material can be detected in a slip-stream sampling mode. There is presently no detection system that will sound an alarm to warn a user that a CB attack on their water system has occurred, but all the components are either available or being developed and the possibility of a detection system capable of this is in the near future. TYPE OF WATERBORNE CBR THREAT AND LEVEL OF SEVERITY There are three levels of threats to water system security. See Table 1. TABLE 1. THREE LEVELS OF CBR THREAT SEVERITY 1 Low level is where the agent is not stable in water for periods greater than two hours 2 Medium level is where an agent is stable in water more than two hours or up to several days 3 High level where the agent is stable in water longer than 30 days (e.g. a radioactive material) Levels of Threats Water systems supplying buildings can become contaminated from a terrorist CBR agent release, or from an intentional or accidental toxic industrial or agricultural chemical release at any one of three stages: (1) at the source (well fields/production wells, reservoirs, lakes and rivers, or water treatment plants), (2) in distribution lines and loops feeding buildings (on- and off-base), or (3) in a building?s system of pipes, pressure tanks, holding tanks or water softener treatment system. Two factors, (1) dilution and (2) the residual chlorine or disinfectant content of treated water, generally make it difficult to introduce an effective dose of a CB agent at the source water and treatment plant. Due to the dilutio
- Water & Waste Management > Water Management > Water Supplies & Services (1.00)
- Water & Waste Management > Water Management > Lifecycle > Treatment (1.00)
Electrochemical Techniques: Investigation of Corrosion in a Major Metropolitan Wastewater Treatment Facility
Tinnea, Jack (Tinnea & Associates) | Covino, Bernard S. (U.S. Department of Energy) | Bullard, Sophie J. (U.S. Department of Energy) | Cramer, Stephen D. (Robert Isaac) | Holcomb, Gordon R. (U.S. Department of Energy) | Ziomek-Moroz, Malgorzata (U.S. Department of Energy) | Isaac, Robert (U.S. Department of Energy) | White, Sarah C. (Metro-King County-WTD) | Kane,, Russell D. (Metro-King County-WTD) | Eden,, Dawn E. (InterCorr International, Inc.) | Eden, David A. (InterCorr International, Inc.)
ABSTRACT This paper discusses the application of electrochemical techniques in the investigation of premature corrosion failure encountered in a major metropolitan wastewater treatment plant. Electrochemical noise, linear polarization, harmonic distortion analysis, electrical resistance and wet chemistry techniques were combined to define the extent and investigate the cause of aggressive corrosion behavior observed at the facility. How these methods were applied and the results of the combined approach investigation are presented. INTRODUCTION In recent years, electrochemical techniques and equipment that once were the province of laboratories are seeing successful industrial application1,2,3. Initially, this took the form of simple voltage logging of either structure corrosion potentials or voltage-like readings such as current measures logged as voltage-drops across a shunt. Field-portable potentiostats and galvanostats followed. More recently, equipment that allows field logging of electrochemical noise has reached the market. The availability of a wide-range of electrochemical equipment provides today?s corrosion engineers and scientists the means to monitor corrosion on-line and in real-time that were unimaginable just a few years ago. SITUATION DESCRIPTION The 32-acre West Point Treatment Plant is located on the shores of Puget Sound approximately four miles north of downtown Seattle, Washington (see Figure 1). It is part of a system run by King County that serves over 1.4 million people. The West Point facility processes approximately 473-million liters (125-million gallons) of wastewater each day. It is located next to Discovery Park, Seattle?s largest and most natural recreational area. To better understand the investigation and its results, a basic understanding of the treatment process is helpful. Following is a brief discussion of the treatment process: ? Wastewater arrives at the plant and undergoes preliminary treatment where screens remove large stick, rocks and rags ? After the preliminary treatment, the wastewater goes to preaeration tanks where the velocity is slowed allowing heavy sands and grit to settle ? Next is primary treatment where flow is slowed further and about 60% of the solids and pollutants settle out ? The primary process is essentially one of settlement, while the secondary process uses aerobic bacteria to digest suspended organic material ? From primary treatment the process stream, now called primary effluent (PE), is pumped to the secondary aeration tanks where oxygen is bubbled through the steam ? From the secondary aeration tanks the stream moves to secondary clarifiers where bacteria and other fine material settles out ? A recursive line returns approximately 25% of the flow back from the clarifier to the aeration tanks ? this is known as the return activated sludge (RAS) line ? After secondary treatment, the effluent is disinfected and discharged into Puget Sound In 1996 major expansion and upgrading to the secondary treatment stream was completed. In December of 2002, a 760 mm (30- inch) diameter mild steel pipe elbow in the RAS line of that upgraded treatment stream deve loped a leak and required repair (see Figure 2). Figure 3 shows a thru-wall pit failure of the RAS elbow. The pipe interior was coated with a quality coal tar epoxy. Figure 4 shows pits concentrating along a weld seam in the pipe elbow. Although pits tended to locate near welds, there were pits located in non-welded areas of the elbows. There was also some blistering of the coating. Some blisters covered corrosion activity and pits and were slightly acidic (pH~6.0). Other blisters covered non-corroded areas and were alkalin
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Treatment (0.61)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations (1.00)
- Health, Safety, Environment & Sustainability > Environment (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
ABSTRACT Stress Assisted Corrosion (SAC) of boiler tubes and economizer tubes from the waterside is one of the major problems in availability loss and safety of power plants and industrial boilers. Use of carbon steel for the service of high temperature water applications strongly depends upon formation and stability of the protective oxide film of magnetite, Fe3O4, on the waterside surface of boiler tubes. Failure mechanisms involved in waterside SAC surely includes film damage as an important step. To understand SAC, a recirculation loop autoclave facility for high temperature water testing was set up. The autoclave was designed for tests under industrial boiling water conditions. The maximum operational temperature is 350oC, with test pressures of up to 3500 psi and flow rates of up to 10 liters per hour. Boiler water chemistry can be changed during the test and the dissolved oxygen can be controlled within the range of 10 ppb - 32 ppm. Initial tests were conducted to develop magnetite film on carbon steel tube samples at different temperatures. INTRODUCTION Casing-side tube leaks in water-filled utility boiler tubes were first reported in the 1960?s(1). In the utility industry the mechanism of cracking of boiler and economizer tubes from the waterside is generally referred as corrosion fatigue cracking of boiler tubes and has been recognized as a major cause of tube failures and reduced availability in utility boilers (1,2). The Electric Power Research Institute (EPRI) began a research project to study the problem in the late 1980?s (1). However, waterside corrosion problems are also experienced by industrial boilers where the temperatures, resulting boiler pressures, and water chemistries can be significantly different. SAC is typically associated with pressure/non-pressure attachments in boiler waterwalls and economizers. Such locations are windbox attachments, tie bars, scallop bars, seal plates and locations solidly welded together like areas with thick attachment welds from the cold-side of tubes are most common sites for SAC failures. Boiler operation guidelines or best practices to avoid corrosion fatigue in the utility power industry came out of EPRI projects and are typically followed in the utility industry (1, 2). In the pulp and paper industry, any water leak into the boiler can potentially cause smelt/water explosion and has led to a number of fatal accidents. In the late 1980?s, US manufacturers of black liquor recovery boilers for the pulp and paper industry realized this potential problem and a number of publications came out describing this type of cracking as stress assisted corrosion (SAC) (3-6). Studies by Schoch and Spahn (7) showed that the morphology of SAC produced in controlled corrosion fatigue tests depended critically on the oxygen content of the water environment. This research was concerned with corrosion fatigue cracking in the low-pressure environments of industrial deaerators. Esmacher (8) reported five case histories on the effect of residual stresses (from fabrication or welding) on the water-side corrosion performance of carbon steel boiler tubing. Cases are reviewed in which tube swaging or bending operations producing high forming stresses in deformed zones resulted in the formation of stressenhanced corrosion cells. The phenomenon of accelerated corrosion in welded support zones, membrane-welded panel sections, and weld-repaired areas was discussed. A number of publications described corrosion fatigue problem in carbon steel tubes in utility boilers (8-11). Use of carbon steel in high temperature water applications strongly depend upon the formation and stability of protective magnetite, oxide film on the waterside surface of
- Materials > Metals & Mining > Steel (1.00)
- Energy > Power Industry (1.00)
- Water & Waste Management > Water Management > Lifecycle > Test/Measurement (0.34)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.89)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.89)
ABSTRACT This paper reviews experience with installation and use of a cycle chemistry expert system. To help power plant operators and chemists to control cycle chemistry and corrosion, the expert system was developed based on industry guidelines and experience. This software uses inputs from plant analytical and other instrumentation and grab sample analyses to determine current water chemistry and corrosion problems and recommend corrective actions. It also verifies the chemical analytical data, automatically produces reports, and provides cycle and water treatment descriptions. Using this program, the status of the cycle chemistry for multiple units can be monitored simultaneously through the utility's computer network. The plant customized Simulators allow operators and chemists to be trained in water chemistry control and problem recognition for their specific power plant. This program currently covers drum and once-through boiler units with and without condensate polishers, using acid and alkali-forming cooling water, all-ferrous and mixed metallurgy, and phosphate, equilibrium phosphate, sodium hydroxide, AVT, and oxygenated treatments. The experiences with installation of this software at five locations is summarized and, based on this experience, recommendations for future work are presented. INTRODUCTION Today's competitive environment and shortages of electric power require operation of the utility power plants at top efficiency with minimum forced outages. Corrosion, scale, and deposits have been the number one contributor to the increased cost of steam and power generation ~. The highest component of this cost is the cost of replacement power, which has been up to $300/MWh, and during the summer of 2000, reached up to $10,000/MWh in the U.S. At the same time, many plants do not have a round-the-clock chemist, and the control room operators, often not trained in water chemistry control, are the first line of defense. Each year, serious contaminant events happen and the operators do not know how to respond. The result can be serious damage to the unit and the need to chemically clean various parts of the plant. EPRI ChemExpert 2 (referred to hereafter as "the program" in accordance with NACE rules on the use of Trade Names) was developed to assist plant operators and chemists in water/steam chemistry and corrosion control and problem diagnosis in fossil power plants. It is an expert system that detects chemistry related problems in the steam/water cycle as they occur (Figure 1) and recommends corrective actions. Using this program improves plant control of water and steam chemistry, thereby reducing the likelihood of equipment damage and efficiency loss. Its capability to simultaneously display the current cycle chemistry status of multiple units~ and its ability to be viewed remotely over a computer network make this program useful for operators and chemists, as well as plant and corporate managers.
- Materials (1.00)
- Energy > Power Industry (1.00)
- Water & Waste Management > Water Management > Water Supplies & Services (0.54)
- (2 more...)
ABSTRACT Produced water injection systems are an integral part of many oilfields. Typically they transport produced water from a central pumping facility to a number of injection wells. The two main purposes of produced water systems are to maintain voidage in the reservoir and to maintain reservoir pressure. The subject produced water system was installed in the early 1970?s and was originally internally coated with cement mortar lining (CML). This lining was applied to the main injection lines, laterals and risers. Failures began to occur after about 15 years of service and were due to cracking, spalling and degradation of the CML. These leaks resulted in environmental damage and excessive spill clean up and repair costs. An extensive program to rehabilitate the system was undertaken. The main pipeline sections were re-lined with high-density polyethylene (HDPE); spools and risers were internally coated with fusion bond epoxy (FBE). After about ten years, failures began to occur in the refurbished pipe spools coated with FBE. Coating failures were attributed to inadequate surface preparation, inconsistent coating thickness and improperly installed flange gaskets led to other failures. Due to environmental impact and high clean up costs, and resulting management and regulatory pressure, it was decided to replace all buried spool pieces. Various alternatives such as corrosion resistant alloys, weld overlays and internal lining with HDPE were considered. Organic coatings were again chosen because of their overall past performance and cost. A holistic approach was taken to the rehabilitation program. This included the fabrication of complex pieces to make them more coater friendly, process changes by the applicator to enable more consistent coating application and a more rigorous specification and inspection program. INTRODUCTION The Nipisi Field is located approximately 375 kilometers north west of Edmonton, Alberta, Canada. The field was discovered in the late 1960?s and produces oil from the Gilwood Sand of the Devonian period. The field now produces about 830 m3 (5230 BBLS) of oil per day and 22,000 m3 (138,600 BBLS) per day of produced water. DISCUSSION Field Review The original produced water disposal system was cement mortar lined (CML) and was installed in the early 1970?s. The system consists of approximately 187 kilometers (119 miles) of pipe ranging in size from 88.9 mm (3 nominal) to 273.1 mm (10 nominal) and is broken into six segments. A summary of the six segments and the size and length of pipeline in each is given in Table 1. Nominal discharge pressure at the water injection plant is 23,000 kPa (3,335 PSI) at a temperature of approximately 45oC (113oF). The produced water is a high salinity brine with a chloride content of about 73,600 mg/l and total dissolved solids (TDS) of 123,000 mg/l. The system currently handles about 22,000 m3 (138,600 BBLS) of water per day.
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Health, Safety, Environment & Sustainability > Environment > Water use, produced water discharge and disposal (1.00)
- Facilities Design, Construction and Operation (1.00)
INTRODUCTION ABSTRACT A test programme was conducted to study the corrosion behaviour of a range of steels and CRAs in low oxygen content (20 & 200 ppb) seawater. The test materials ranged from carbon and low alloy steels through austenitic, martensitic and duplex stainless steels to nickel-based Alloy 718. Seawater injection conditions were simulated in tests conducted in the above conditions at 30ยบC. Commingled water (a mixture of produced water and injected seawater) was simulated by adding carbon dioxide to these test environments and testing at 60ยบC. High oxygen levels were injected periodically to simulate the effects of poorly controlled seawater deaeration. Tests were conducted in static and flowing conditions. The results show the sensitivity of these materials to the dissolved oxygen content of injection and commingled waters. Pitting, crevice and under-deposit corrosion occurred to varying degrees enabling guidelines to be developed for material selection in this area. BP Exploration and Statoil commissioned CAPCIS Ltd to undertake a test programme at CAPCIS? Marine Test Facility, Holyhead, Anglesey, UK. The objective of the work was to determine the corrosion behavior of certain low alloy steels, stainless steels and corrosion resistant alloys in simulated sea water and commingled produced water/sea water injection systems at nominal test temperatures of 30ยฐC and 60ยฐC respectively. Two dissolved oxygen concentrations were selected, nominal 20 ppb and 200 ppb, each with periodic excursions to higher concentration, representing well and poorly controlled deaeration systems respectively: Additional test parameters included flowing (5 ms-1) and static conditions to simulate shut-in periods during operation. Carbon dioxide was added to reduce the pH of the commingled produced water/sea water at 60ยฐC to between 5.5 and 6.0. The programme was conducted in order to generate better guidance for materials selection for downhole tubing and flowlines.
- North America > United States (0.28)
- Europe > United Kingdom > Wales > Isle of Anglesey (0.24)
- Research Report > New Finding (0.34)
- Research Report > Experimental Study (0.34)
- Materials > Metals & Mining > Steel (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.54)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- (2 more...)
ABSTRACT The Furrial reservoir exploitation unit is located in the eastern part of Venezuela and from 1993 it has shown calcium carbonate scale problems due to the injection of water for the secondary recovery of oil. The producing wells in this field have shown recurring failures because of calcium carbonate deposition; in fact, there have been production delays because of this phenomenon. In order to avoid future holdups and problems in the production of oil at the Furrial field, it is necessary to apply treatments that will control scale deposition. Nevertheless, these treatments should be directed at the wells with a greater scaling tendency at the time of application and then to those wells with lesser risk of deposition. A critical analysis was performed on the 63 producing wells that make up the Furrial UEY in order to arrange the wells in a hierarchy according to their scaling character. This hierarchy was constructed based on the calculations of different factors that affect the deposition of calcium carbonate: water composition and volume, pressure decrease and failure frequency. From this ranking a matrix was developed that places wells in a hierarchy in order of non-critical, semi-critical, and critical according to their scaling tendency and the occurrence of failures due to deposition of calcium carbonate. INTRODUCTION Because of the secondary recovery of oil through water injection which began in 1993 at the Furrial Field, there have been found production problems and evidence of scale in the field because of the precipitation of minerals from the aqueous phase present in the system. Based on lab tests, it was found that the problematic mineral was calcium carbonate (CaCO3)1. Since then, the problems have grown and production delays have been well-known. Field observations determined that blockages due to scale deposition have been common at the top of the well, specifically in the reducer, tightening box, and down pipe. A scheme of this system is shown in Figure 1. These blockages were more frequent in some wells, which indicated a need to understand which were higher risk wells that required immediate treatment and then later to evaluate whether the treatment in the lower risk wells was adequate. In this study, many different factors that affected the scaling tendency of a system were considered (saturation index, potential mass of precipitation, and pressure drop) and the occurrence of failures in each well due to the presence of scale. These factors were used in order to arrange the wells in a hierarchical order in a matrix by scaling risk level: non-critical, semi-critical, and critical. It was found that five wells showed a critical scale level, twelve were categorized as semi-critical, and forty-five were non-critical; the latter included those wells whose current production of water is less than 3 BPD. This analysis allowed highlighting of the wells that required immediate treatment in order to avoid production delays and identification of those wells that were candidates for preventative scale treatment. Scaling Tendency Analysis of the Furrial Field The Furrial field is composed of five reservoirs, each of which is produced by several wells. The largest reservoir is the lower Naricual which has 36 wells, followed by the mid Naricaul which has 20, the upper Naricual with 17, the Cretaceo with 8, and the mid Naricual-upper Naricual with 7 wells. Field observations along with scaling tendency predictions showed that the scale deposition in the Furrial Field production wells consisted primarily of calcium carbonate and occurred near the surface where changes in calcium carbonate solubility occur. As fluids ascend t
- South America > Venezuela (1.00)
- North America > United States > Texas > Dawson County (0.34)
- Materials > Chemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.61)
INTRODUCTION ABSTRACT The formation brine in a giant carbonate reservoir had high total dissolved solids (more than 200,000 mg/L) and high calcium ion concentration (more than 25,000 mg/L). In an effort to assess compatibility with seawater and formation of sulfate scale, two types of field tests were conducted: 1) Seawater was directly pumped down the tubing-casing annulus into three wells (A, B and C) where it was commingled with the produced water in the wellbore, and 2) seawater was injected into a well 1,000 feet from a producer (D). At the end of the test period, only well-A experienced severe Ca/Sr-SO4 scale in the tubing. Various data were collected during these tests which gave a unique opportunity to validate the output of scale prediction models using real field data. Most of the available scale prediction models are based on experimental solubility and/or thermodynamics data. However, it was possible to correlate the predicted saturation indices and scale amounts with the field data to obtain the critical saturation index and amount of CaSO4 scale in the producing wells. OKSCALE scale program (University of Oklahoma) was correlated with company wide field observations. CaSO4 was found to exhibit its highest scale amount at 70 vol% of seawater. In the case of well-A, the average seawater percentage in the produced water was 45 vol%. On the other hand, seawater was less than 20 vol% for wells-B and C. The thermodynamic calculations indicated that the degree of CaSO4 super-saturation was apparently not high enough to form scale in well-A & B. In the case of well-D, the volume of seawater in produced water peaked at 60 vol%, but stabilized at 40 vol%. The accelerated seawater flood in well-D should have resulted in super-saturation and sulfate formation in the reservoir. This possibility was reflected in the equilibrated calcium and sulfate ionic ratio present in the produced water. The critical saturation index and scale amount for CaSO4 were found to be 0.25 and 450 mg/L, respectively. The absence of any major sulfate-scaling problem in this field despite the seawater flood for more than 25 years is attributed to the injection of compatible aquifer waters before the onset of seawater injection. These waters created a buffer zone, which minimized mixing of the seawater with the formation water. Water injection into oil producing reservoirs has been a common practice used to maintain reservoir pressure and therefore enhance production rates. However, possible source of flood waters should be evaluated for its compatibility with formation waters. Seawater flood into formations containing high Ca/Sr/Ba ions caused sulfate scale incompatibility1-3. Sulfate reduced seawater has been used for waterflooding in the North Sea and Gulf of Mexico to avoid severe barium sulfate scaling4-6. Ghawar (G) field is the largest on-shore oilfield in the world. It is a carbonate reservoir that has an average temperature of 220oF and pressure of 3,000 psi. The associated gas has 5 - 15 vol% CO2 and up to 5 mol% H2S. The formation water composition varied significantly from north to south. Calcium carbonate was the most common scale encountered in this field7. However, small amounts of calcium/strontium sulfates were noted in a few wells. A peripheral water injection program (one kilometer from first row of producers) to support reservoir pressure in Field-G was started in 1966. The performance of seawater injectors in this field was reviewed by Bayona8. Initially, low-salinity aquifer water by gravity injection (Aquifer-B in Table 1) was used. In 1974, power water injection using another low-salinity Aquifer-W water was started (Table 1). Seawater injection in t
- North America > United States (1.00)
- Asia > Middle East > Saudi Arabia (1.00)
- Europe > United Kingdom > North Sea > Central North Sea (0.28)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.74)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > Block 22/24 > Eastern Trough Area Project > Heron Cluster > Skagerrak Formation (0.99)
- Europe > United Kingdom > North Sea > Central North Sea > Central Graben > Block 21/10 > Forties Field > Forties Formation (0.99)
- Asia > Middle East > UAE > Dubai > Arabian Gulf > Rub' al Khali Basin > Fateh Field > Thamama Group Formation (0.99)
- (11 more...)
ABSTRACT The following paper presents the corrosion performance of high-mechanical strength alloys immersed in Lake Maracaibo (Venezuela) brackish water at ambient temperature, these were: AISI 1018 Carbon steel, AISI 4140 low alloy steel, martensitic stainless steel type 416, precipitation hardened stainless steel type 17-4 PH, austenitic stainless steel types 304, 316 and XM-19, and the precipitation hardened Ni-Cu Alloy K-500. The alloys were metallurgically characterized through chemical, metallographic, and hardness analyses. Throughout the immersion of specimens in the water of the lake their tendencies to biofouling were qualitatively determined and the corrosion products were characterized. It identified the types of corrosion that affected them and it was quantitatively established the speed of attack. Conducting potentiodynamic polarization resistance and cyclic potentiodynamic polarization measurements, it was determined the electrochemical parameters that define the behavior of these alloys with respect to the corrosion by water of the Lake Maracaibo. The results of the following study allowed identifying the stainless steel types XM-19, 316, 304 and 17-4 PH as the alloys of high mechanical resistance recommended to be employed in immersion services in the water of the Maracaibo Lake at ambient temperature. There were established selection criteria for the best use of these alloys. INTRODUCTION Lake Maracaibo water possesses peculiar characteristics that affect the corrosive behavior of the alloys immersed in it. The constant entrance of sea water, the pollution from domestic and industrial disposals and the elevated presence of micro and macro organisms provide to the water of the lake a high content of oxygen, chlorides and dissolved solids, as well as a great tendency to biofouling [~4], aspects that confer a highly corrosive character that negatively affects the performance of the alloys that operate in direct contact with this environment. A critical application is represented by components that operate in services of high mechanical performance such as propulsion shafts of floating units as well as parts of high-pressure pumps. These components require alloys that possess good mechanical properties in combination with excellent resistance to the corrosion because they are particularly susceptible to fail in service under mechanical (fatigue, plastic deformation) and/or corrosives mechanisms (pittings, crevice, environment induced cracking) [5-~0]. The improper selection of materials is one of the principal causes associated with the occurrence of these failures. The high economical impact associated to the replacement and/or maintenance of the failed component and the lost production has led out to the continuous search of adequate materials that offer the best output at the lowest possible cost. Within this line of investigation, the present study was focused to identify the alloys of high corrosion resistance and mechanical resistance to be employed in immersion services in Lake Maracaibo, at ambient temperature, and to establish a selection criterion for these alloys.
- Materials > Metals & Mining > Steel (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Sourcing (0.61)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)