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53 NACE INTERNATIONAL: VOL. 55, NO. 12 MATERIALS PERFORMANCE DECEMBER 2016 • Reservoir souring—When bacteria, particularly sulfate-reducing bacte- ria, breed and multiply in the reser- voir, their metabolic activities cre- at e hydrogen sulf i d e (H 2 S). Th e produced H 2 S can gradually turn the reservoir sour and consequently cre- ate sour corrosion problems on the production side. • R e s e r v o i r f o r m a ti o n c l o g g i n g — Solid bacterial products produced by the bacteria (e.g., biofilm and slimes) and insoluble iron sulfide scales can gradually reduce both optimum chemical injection and production. Bacterial mitigation is carried out in two stages. First, an oxidizing chemical such as chlorine (often in the form of hypo- chlorite) is added to the seawater, upstream of the deaeration process. Thereafter, an organic biocide is injected into the system, often downstream of the deaeration pro- cess. The oxidizing treatment (i.e., chlori- nation) is a continuous one, whereas the biocide treatment is carried out on a batch basis, typically every few days. The most commonly used organic bio- cides are solutions of gluteraldehyde or formaldehyde. Sometimes, such chemicals are blended with other agents such as a qua- ternary ammonium compound to give the biocide more penetration power or capabil- ity against bacterial colonies and biomasses. Observed Shortcomings Associated with MIC Mitigation The observed shortcomings could be divided into the following two categories: • Specific shortcomings • General or common shortcomings Specific shortcomings are those often associated with one of the four main stages of MIC mitigation: • Sampling • Analysis (i.e., determining bacterial types and their populations) • Chemical treatment • Per formance monitoring (of th e chemical treatment or mitigation action) TABLE 1. OBSERVED SHORTCOMINGS ASSOCIATED WITH A TYPICAL MIC MITIGATION PROGRAM Activity Observed Shortcomings Sampling • Using the wrong sampling technique (or lack of sampling procedure) • Sampling at the wrong location • Sampling at the wrong time intervals • Using dirty or previously used containers for taking new samples • For diesel systems, taking samples from the diesel side and not the water side • Only taking planktonic samples and ignoring sessile sampling Analysis • Only relying on one method for measuring residual oxygen concentration • Using the same syringes during the serial dilution process • Only looking for planktonic bacteria • Not having proper lab procedures to follow during the analysis stage Chemical treatment • Using new chemicals prior to any previous lab testing • Injection at the wrong concentration • Injection at the wrong location • Injecting the wrong or chemically incompatible chemicals • Using the same biocide for a prolonged time • Using wrong injection frequencies Performance monitoring • Not carrying out any performance monitoring for any/some of the applied mitigation activities • Not specifying any performance thresholds, values, or ranges • Not rectifying, improving, or modifying the carried out mitigation activity even though the measured performance was unacceptable or simply out of the specified range The general, or common, shortcomings are those that adversely affect all four of the mitigation stages. These general short - comings include: • Inadequate competency levels or lack of training among those who carry out the four stages • Poor data management Data management for a seawater injec- tion system is the process of collating all the various input (e.g., residual chlorine and oxygen levels and the biocide injection rate); verifying their accuracy and reliabil- ity ; analyzing; and, where applicable, trend- ing and plotting the data. Case studies have found that the tradi- tional or historical integrity management approaches only address some of the spe- cific shortcomings and the common or general shortcomings are seldom taken into account. Such approaches or notions would never fully resolve the integrity man- agement issues associated with a typical seawater injection system. Traditional ap- proaches leave personnel competency/ training requirements and data manage- ment procedures/practices out of any re- view or solution. In spite of the availability of some of the best hardware (e.g., online sampling/monitoring devices and effective