1、 Standard Practice Corrosion Control and Monitoring in Seawater Injection Systems This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone, whether he or she
2、has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be construed as granting any right, by implication or otherwise, to manufacture,
3、sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requirements and should in no way be interpreted as a restriction on the use of
4、better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International assumes no responsibility for the interpretation or use of this standard b
5、y other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE International standa
6、rd are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may not necessarily address all potential health and safety problems or environ
7、mental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with app
8、ropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with N
9、ACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication and subsequently from the date of each reaffirmation or revision. The user is cautioned to obtain the late
10、st edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Dr., Houston, Texas 77084-4906 (telephone +1 281-228-6200) Reaffirmed 2012-
11、07-09 Revised 2007-05-11 Approved 1999-06-25 NACE International 1440 South Creek Dr. Houston, Texas 77084-4906 +1-281-228-6200 ISBN 1-57590-083-1 2013, NACE International SP0499-2012 (formerly TM0299-99)Item No. 21237 SP0499-2012 NACE International i _ Foreword This NACE standard practice provides g
12、uidance in controlling and monitoring for corrosion, bacteria, and water quality to corrosion engineers, field corrosion, production, technical, and operating personnel, and others involved in corrosion control of seawater injection systems. This standard includes descriptions of equipment and pract
13、ices for controlling and monitoring corrosion in seawater injection systems. This standard was originally adapted from a report produced by the former Corrosion Engineering Association (CEA), which operated in the United Kingdom under the auspices of NACE International and the Institute of Corrosion
14、 (ICorr).(1) The standard was developed as a test method (TM) in 1999 by Task Group (TG) T-1D-47, a component of Unit Committee T-1D, “Corrosion Monitoring and Control of Corrosion Environments in Petroleum Production Operations,” and revised in 2007 and 2011 by TG 345, “Corrosion Monitoring in Seaw
15、ater Injection Systems: Review of NACE Standard TM0299-99.” During the 2007 revision, the TG decided to change the designation of the standard from a TM to a standard practice (SP). TG 345 is administered by Specific Technology Group (STG) 31, “Oil and Gas ProductionCorrosion and Scale Inhibition.”
16、This standard is issued by NACE International under the auspices of STG 31. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must are used to state a requirement, and are co
17、nsidered mandatory. The term should is used to state something good and is recommended, but is not considered mandatory. The term may is used to state something considered optional. _ (1) Institute of Corrosion (ICorr), Corrosion House, Vimy Court, Leighton Buzzard, Bedfordshire LU7 1FG, United King
18、dom. SP0499-2012 ii NACE International _ Standard Practice Corrosion Control and Monitoring in Seawater Injection Systems Contents 1. General 1 2. The Need for Corrosion Control 2 3. Corrosion Control in Seawater Injection Systems . 2 4. Monitoring of Seawater Injection Systems 4 5. Materials Select
19、ion for Seawater Injection Systems . 9 References 10 Bibliography 11 TABLES Table 1: Recommendations for Injection System Materials 10 FIGURES Figure 1: Layout of a typical water injection system . 1 _ SP0499-2012 NACE International 1 _ Section 1: General 1.1 This standard covers aspects of corrosio
20、n control and monitoring in seawater injection systems. 1.2 Most seawater injection systems rely on coatings, liners, plastics, composite materials, and corrosion-resistant alloys (CRAs) to overcome potential corrosion problems prior to deoxygenation. The practices in this standard concentrate more
21、on controlling and monitoring corrosion in facilities downstream from deoxygenation, but also address some of the aspects relevant to selection of appropriate mitigation and control methods for upstream service conditions. The standard also addresses materials selection for seawater injection system
22、s. 1.3 This standard presents practices for controlling and monitoring corrosion in seawater injection systems. However, many of these practices may be applied to other types of water injection systems, such as: (a) Systems for reinjection of produced water; (b) Aquifer-sourced water injection syste
23、ms; and (c) River or surface water injection systems. 1.4 Figure 1 shows a typical layout of a water injection systemin this case, an offshore application. The purpose of Figure 1 is to show equipment items typically associated with water injection systems and common fluid treatments and monitoring
24、types and locations. It does not show all items of equipment or all possible fluid treatments or monitoring types that can be used in water injection systems. Figure 1: Layout of a typical water injection system, indicating recommended chemical treatment locations and monitoring points. S e a w a te
25、 r lif t p u m p D e a e r a t o r t o w e r C o a r s e f ilt e r s F in e filt e r s In je c t io n p u m p s B o o s t e r p u m p s S e a w a te r lif t c a is s o n In je c t io n d is c h a r g e h e a d e r F lo w lin e s (1) (2) (3) (4) (3) (5) (6) (7) (8) (9) (9) (9) (9) (9) (1 0 ) (1 0 ) (
26、1 0 ) (1 0 ) K e y to F ig u r e : (1 ) A d d itio n o f c h lo r in e /e le c tr o c h lo r in a tio n (2 ) A d d itio n o f filtr a t io n a g e n ts (3 ) C h lo r in e m o n it o r in g u p s tr e a m a n d d o w n s tr e a m o f d e a e r a t o r (4 ) In je c tio n o f o r g a n ic b io c id e (
27、5 ) G a lv a n ic p r o b e (6 ) p H , o x y g e n a n d r e s id u a l o x y g e n s c a v e n g e r m o n ito r in g (7 ) Mo n it o r in g o f s u s p e n d e d s o lid s , s e s s ile a n d p la n k to n ic b a c te r ia (8 ) O x y g e n m o n it o r in g d o w n s tr e a m o f in je c tio n p u
28、m p s (9 ) P r o b e s /c o u p o n s /b io p r o b e s o n in je c t io n d is c h a r g e h e a d e r a n d flo w lin e s (1 0 ) W e llh e a d m o n it o r in g o f flo w r a te , te m p e r a tu r e a n d p r e s s u r e SP0499-2012 2 NACE International _ Section 2: The Need for Corrosion Control
29、 2.1 The importance of controlling corrosion damage in the carbon steel (CS) pipework of a seawater injection system to ensure the integrity of topside and downhole equipment and minimize system operating and maintenance costs is widely recognized. 2.2 Equally important is a requirement to avoid res
30、ervoir formation blockage by corrosion by-products and bacterial debris in seawater injection wells. In oil fields in which recovery of reserves is from a formation with permeabilities of a few millidarcies,(2) this requirement can influence the acceptable level of corrosion and the methods of monit
31、oring and control. Corrosion products (e.g., iron oxide and sulfide) and bacterial biomass have caused considerable damage, even in formations with high permeability. 2.3 The necessary corrosion control strategy is largely dictated by whether the major intent is to control corrosion damage or to min
32、imize formation damage. Therefore, the overall philosophy of operation should be system-specific. When considering corrosion in seawater injection systems, the effect of velocity and entrained solids should also be considered. In addition to technical considerations, the corrosion control philosophy
33、 may also be dictated by environmental considerations or regulatory requirements, particularly regarding allowable chemical treatments. _ Section 3: Corrosion Control in Seawater Injection Systems 3.1 Corrosion in seawater injection systems is usually caused by the presence of oxygen, bacteria, or c
34、oncentration cells from solids in the seawater. 3.2 Deaeration (i.e., removal of dissolved oxygen) should be used to control oxygen corrosion in seawater injection systems. 3.2.1 Mechanical deaeration of the seawater is usually achieved by passing production gas through the seawater in an exchange t
35、ower, or by vacuum deaeration in a tower. 3.2.2 When production gas stripping is used, the corrosiveness of the stripping gas is a factor that may require special attention, particularly when the carbon dioxide (CO2) in the produced gas dissolves to form a corrosive solution, or when produced or fue
36、l gas contains hydrogen sulfide (H2S) or sulfur dioxide (SO2). 3.2.3 Mechanical deaeration alone may not be efficient enough to reduce the oxygen concentration to a level at which the corrosiveness of the seawater is acceptable. 3.2.4 In addition to the long-established system of gas stripping and o
37、xygen scavenging in a tower (see Figure 1), commercial methods that are more compact and are well-suited to applications in which space is at a premium have become available. Such systems differ from conventional larger gas stripping towers in that they use a recirculating nitrogen stream as the str
38、ipping medium, which is then regenerated for further use. The use of chemicals for oxygen removal may be reduced or eliminated by the use of such units, depending on the ultimate water quality required. In such systems, there is often a resultant reduction in pH, and this should be considered when s
39、electing materials for construction of equipment downstream from such units. 3.3 An oxygen scavenger, such as ammonium or sodium bisulfite, shall be added to the seawater after mechanical deaeration to ensure adequate oxygen removal to control corrosion by oxygen. 3.3.1 The type and quality of the o
40、xygen scavenger used is a key factor. 3.3.1.1 Sodium sulfite, a dry powder, must be dissolved in water and is not very soluble. The solution, being dilute, reacts quickly with atmospheric oxygen if stored in an open container exposed to air. 3.3.1.2 Ammonium bisulfite and sodium bisulfite, manufactu
41、red in liquid form and not required to be dissolved in water prior to injection, are more convenient to use. These are concentrated solutions and are not as sensitive to air exposure. Ammonium bisulfite is the more concentrated of the two and is somewhat more resistant to degradation from exposure t
42、o air. However, both of these materials should be stored to eliminate or minimize exposure to air. (2) Millidarcy: 0.001 darcyunit of measure of permeability; from Petroleum Engineers Handbook (Richardson, TX: Society of Petroleum Engineers, 1987). SP0499-2012 NACE International 3 3.3.2 Oxygen scave
43、ngers require time to react with the oxygen, and the part of the system immediately downstream from the scavenger injection point may not be totally protected against oxygen corrosion. 3.3.3 The rate of reaction of the scavenger with oxygen depends on several factors, including the formulation of th
44、e oxygen scavenger, the pH, the presence of interfering ions such as sulfide and calcium, and the temperature. Some oxygen scavengers can be catalyzed (e.g., bisulfites by the addition of cobalt 15 parts per billion (ppb) of 2% cobalt chloride solution) to speed up the reaction. Addition of the cata
45、lyst separately has been found to have the most beneficial results in speeding up reaction time. The presence of H2S can slow reaction rates and interferes with catalysts. 3.3.4 In some systems, there has been evidence to suggest that excessive amounts of oxygen scavengers above those required to st
46、oichiometrically remove oxygen can lead to an increase in the corrosion rate. 3.3.5 There have been suggestions that oxygen scavengers may undergo a chemical reaction under some circumstances, producing H2S in small quantities, and this could affect the corrosion rate under actual system conditions.
47、 This theory is based on the results of laboratory tests. This view is currently not widely supported. Greater quantities of sulfide may potentially be released in the system as a result of the activity of sulfate-reducing bacteria (SRB). 3.4 Both aerobic and anaerobic bacteria are normally present
48、in seawater and can become active in different parts of the injection system. 3.4.1 Oxidizing biocides (primarily chlorine Cl2, although bromine Br2 has a similar effect) should be used for control of microorganisms in the aerobic part of the seawater injection system (i.e., upstream from oxygen removal). Cl2 can be generated by electrolysis from seawater, added via a gaseous sou
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