1、 Standard Practice Handling and Proper Usage of Inhibited Oilfield Acids 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 has adopt
2、ed 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, sell, or
3、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 better pr
4、ocedures 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 by other p
5、arties 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 standard are re
6、sponsible 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 environmental ha
7、zards 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 appropriate
8、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 CAUTIONARY NOTICE: NACE International standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE techn
9、ical 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 latest editio
10、n. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International First Service Department, 1440 South Creek Dr., Houston, Texas 77084-4906 (telephone +1 281/228-6200). Reaffirmed 2007-03-11 R
11、eaffirmed 2001-03-15 Revised March 1995 Approved 1973 NACE International 1440 South Creek Drive Houston, Texas 77084-4906 +1 281/228-6200 ISBN 1-57590-122-6 2007, NACE International NACE SP0273-2007 (formerly RP0273) Item No. 21009 SP0273-2007 NACE International i _ Foreword Acid solutions are often
12、 used to improve the production of fluids from, or injection of fluids in, subterranean formations. The most commonly used acid is hydrochloric acid and solutions thereof, and these solutions are hazardous to personnel and are very corrosive to metal equipment. This standard practice outlines method
13、s and procedures for the handling and use of inhibited hydrochloric acid for oilfield applications. It is intended for individuals who wish to supplement their understanding of oilfield acidizing processes or who handle or use inhibited acids in oilfield operations. This standard was originally prep
14、ared in 1973 by the API(1)/NACE Subcommittee on Oilfield Acid Corrosion Inhibitor Evaluation and jointly issued as API Bulletin D-15 (now withdrawn) and NACE Standard RP0273-73. This standard was revised in 1995 by NACE Task Group T-1D-37, a component of Unit Committee T-1D on Corrosion Monitoring a
15、nd Control of Corrosion Environments in Petroleum Production Operations. It was reaffirmed in 2001 and 2007 by Specific Technology Group (STG) 31 on Oil and Gas ProductionCorrosion and Scale Inhibition and is issued by NACE International under the auspices of STG 31. In NACE standards, the terms sha
16、ll, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual, 4th ed., Paragraph 7.4.1.9. Shall and must are used to state mandatory requirements. Should is used to state something considered good and is recommended but is not mandatory.
17、May is used to state something considered optional. _ (1)American Petroleum Institute (API), 1220 L Street NW, Washington, DC 20005. _ SP0273-2007 ii NACE International _ NACE International Standard Practice Handling and Proper Usage of Inhibited Oilfield Acids Contents 1. General 1 2. General Guide
18、lines for Using Inhibited Acid in Wells 1 3. Field Test of Oilfield Acids for Presence or Absence of Corrosion Inhibitors 3 4. Laboratory Test for Solubility-Dispersibility of Corrosion Inhibitors in Oilfield Acids . 5 5. References 6 Figures Figure 1: Preloaded test ampoule, which is submerged in t
19、he test position in glass beaker of water 4 _ SP0273-2007 NACE International 1 _ Section 1: General 1.1 This standard presents guidelines for minimizing acid corrosion, including general corrosion, pitting, and stress corrosion cracking (SCC), in the oil field. Topics covered include preparation of
20、the well, preparation of the acid solution, acid solution pumping and injection, and return fluids handling. 1.2 This standard presents a field test of oilfield acids of 15% or less concentration for the presence or absence of corrosion inhibitors. 1.3 This standard presents a laboratory test for so
21、lubility-dispersibility of corrosion inhibitors in oilfield acids. _ Section 2: General Guidelines for Using Inhibited Acid in Wells 2.1 This section provides guidelines that should be followed to minimize acid corrosion problems including general corrosion, pitting, and SCC. Guidelines pertaining t
22、o preparation of the well, preparation of the acid, injection of the acid, and subsequent cleanup of the well are presented. While all these guidelines may not be applicable for each acid treatment, the merits of each should be weighed carefully. 2.2 Well Preparation Guidelines 2.2.1 Pipe Conditions
23、: The condition of the pipe in the well should be examined for evidence of corrosion or scaling. Leaks may result from the removal of scale or corrosion products and not from acid corrosion of pipe material. Effects of the acid solution on downhole nonmetallic materials (e.g., plastic-coated or ceme
24、nt-lined tubular goods) should be considered. 2.2.2 Metallic Material Precautions: Acid inhibitors do not protect certain metals from corrosion by acid solutions. Consideration should be given to removal of galvanized metal, aluminum, magnesium, and chrome-plated metal from the well prior to initiat
25、ing treatment. Stainless steel may be susceptible to SCC. Acetic acid can be inhibited for use in the presence of chrome-plated metal, stainless steels, and aluminum, but cannot be adequately inhibited for use in the presence of magnesium or galvanized metal. 2.2.3 Leak Check: Precautions should be
26、taken to ensure that the tubing string and the packer do not leak. If acid solution becomes trapped in the annular space, it can cause damage even if the acid initially was properly inhibited. Severe damage resulting from trapped acid cannot be attributed to lack of inhibitor or inhibitor failure. 2
27、.2.4 Hydrogen Sulfide (H2S) Precautions: Although inorganic acids can cause general corrosion and SCC, H2S may contribute to increasing corrosiveness and SCC of metals. Therefore, sour fluids should be displaced to prevent contamination of the acid solution with H2S. In addition, H2S can be produced
28、 by acid contact with iron sulfide present on the pipe surface. Inorganic inhibitors can be precipitated by H2S. Organic inhibitors are preferred for H2S service although they too can be adversely affected by H2S. 2.2.5 Well Cooling Considerations: Consideration should be given to the practice of co
29、oling a very hot well by injecting oil or water ahead of the acid solution to lower the temperature of the tubular goods. However, precautions should be taken so that the tubular goods will not be cooled to the point of tensile failure or packer release. If the well cannot be cooled below 163C (325F
30、), use of organic acids should be considered. These organic acids can be effectively inhibited for safe use above 204C (400F). 2.2.6 Displacement into Formation: If possible, an acceptable pump-in rate should be established in advance using an inert fluid such as oil or water. This procedure makes c
31、ertain that the formation is open to receive the acid solution to prevent trapping of acid in the tubular goods with no means to effectively displace the acid solution. 2.2.7 Vent Piping: Piping shall be arranged to prevent venting of gases near the wellhead or anywhere rig operators or other person
32、nel may be present. This is especially important if any sulfide or arsenic compounds are present in the well. Personnel must be warned that H2S and arsine gases are heavier than air and tend to collect in low spots (gullies, draws, ravines, etc.), creating a lethal environment. Lethal amounts of H2S
33、 or arsine gas can be produced (1) when wells containing sulfides or arsenic materials are acidized, or (2) when acid containing arsenic materials is being used. If the possibility of H2S or arsine gas exists, testing equipment and appropriate safety equipment shall be on hand to monitor the working
34、 area and protect personnel in the area. Special scrubbing equipment may be required for removal of toxic gases. 2.2.8 Arsenic Inhibitor Precautions: Arsenic inhibitors are still occasionally used in acidizing deep, hot wells. Many refineries use catalysts that can be severely damaged by traces of a
35、rsenic in the parts-per-billion range. Some pipelines and refineries refuse delivery of production containing trace quantities of arsenic. When use of an arsenic inhibitor is being considered, SP0273-2007 2 NACE International the users of production should be consulted to be certain that the traces
36、of arsenic present in production after acidizing are acceptable. 2.2.8.1 Many countries, oil companies, and operators do not permit the use of arsenic-containing compounds and do not consider this application appropriate. 2.3 Acid Solution Preparation 2.3.1 Mixing Tanks: Clean tanks should be used t
37、o prepare the acid solution. Approval of storage tanks may be required by certain regulatory agencies. Rust, gelling agents, or oily residue left from previous usage are undesirable. Such contaminants can affect the inhibitor performance as well as possibly reduce formation permeability. 2.3.2 Acid
38、Solution Mixing: The acid solution should be prepared using fresh water, if possible. If necessary, bay water or seawater may be used in preparing most acid solutions. Bay water, seawater, or potassium-, sodium-, or calcium-containing brines should never be used when mixing hydrofluoric acid or ammo
39、nium bifluoride solutions because of possible precipitation. 2.3.3 Chemical Additives: Some chemical additives interfere with others in acid mixtures. Cationic agents usually interfere with anionic agents and vice versa. Additives that are compatible should be chosen. Supplier compatibility data sho
40、uld be considered to avoid loss of inhibitor and additive effectiveness. Compatibility of acid solutions with well fluids and the formation is also important and should be checked. The user and the supplier should reach some mutual understanding covering necessary specific precautions that should be
41、 invoked in handling acid corrosion inhibitors in use. 2.3.4 Additive Separation: The acid solution should be inspected in the tank at the well location for separation of additives. If additives separate from the solution, the solution must be remixed to disperse the additives. Class II or III mixtu
42、res should be thoroughly mixed immediately prior to injection. (See Section 4 for test procedures and solution classifications.) 2.3.5 Safety in Acid Handling: Strict safety practices shall be followed when preparing and sampling acid solutions or when inspecting the tanks, especially with acid mixt
43、ures containing fluoride. A comprehensive coverage of safety practices can be found in the National Safety Councils(2)Data Sheet 634.12.3.6 Sampling and Testing: Samples of the acid solution should be collected at the well location in a plastic container. If feasible, these samples should be tested
44、for concentration of acid and for presence of inhibitor in the acid solution. Acid concentration can be closely estimated from titration results. Hydrometer readings alone may be used if salt water, hydrofluoric acid, or organic acids are not present in the acid solution. A well-site test may be per
45、formed to determine the presence or absence of inhibitor in 15% or less hydrochloric acid solutions. (See Section 3 for test procedures.) 2.4 Acid Solution Pumping and Injection 2.4.1 Corrosion Rate: At any temperature, but especially at high temperatures, the exposure time of metallic materials to
46、the acid solution should be held to a minimum commensurate with good well practices. The allowable exposure time for different acids at specific conditions depends on the corrosion rate limits established between the user and the supplier. 2.4.2 Packer Placement: When acid is spotted, displacements
47、must be accurately calculated so that no acid is trapped above the packer. 2.4.3 Pumping Shutdown: If the well temperature is above 93C (200F), shutdowns should be avoided during hydrochloric acid or hydrochloric-hydrofluoric acid injection. Precautions should be taken to keep the acid solution movi
48、ng. If the well temperature is very high (121 to 149C 250 to 300F), a standby pump should be available for use in the event that the primary pump malfunctions. If possible, consideration should be given to potential means for reverse circulation of live acid in case conditions dictate such action. 2.4.4 High-Temperature Applications: For well temperatures above 163C (325F), consideration should be given to well cooling to permit inhibitio
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