Water Flood Pilot (WFP) Projects were started during June 1997 in two of North Kuwait's major oil fields to determine the feasibility of waterflooding the Mauddud Carbonate Reservoir. In each of the two pilots, the injection water supply comprised source water well, completed with a downhole electrical submersible pump (ESP) across the underlying Lower Burgan aquifer. Source water rates of up to 10,000BWPD were pumped from the well to a surface booster pump, designed to deliver an injection pressure of 2000 psi at the injection well. A significant part of the feasibility study was monitoring system corrosion. Specific surface measurements included pH, total suspended solids (TSS), corrosion rate derived from Linear Polarization Resistance (LPR) and concentration of injected corrosion inhibitor. This suite of data and associated interpretations are presented and discussed. The data recorded also documents radical fluctuations in LPR and pH measurements several days before ESP failures. Downhole corrosion in producers experiencing breakthrough of injection water is also examined through a sequence of Wireline Micro Vertilog (MVRT) interpretations. Corrosion rate variations relative to produced watercut are presented. In addition, the application of chemical inhibitors and plastic coated surface and downhole tubular are discussed relative to managing the conditions experienced. Finally, the collation of this daily data over a two-year period enables conclusions to be drawn regarding optimum sampling procedures and the advantages and disadvantages of the water system used. The collection of data during this project has resulted in significant learning, some of which is transferable to other waterflood operations. Significant technical contributions are made on corrosion monitoring and inhibition, MVRT interpretation and surface sampling. Introduction In June 1997, Water Flood Pilot projects for two oil bearing traps in the Mauddud reservoir were started, using 5-spot patterns within a 100acre pattern area. The main objectives were to provide reservoir performance information and operational data prior to initiating full field waterflood development. In these projects, the underlying Lower Burgan aquifer was ‘tapped’ with an ESP lifted completion, which then fed the surface booster pump at a supply rate of 10,000BWPD. A 6" OD surface pipeline conveyed the 2000psi aquifer water to the injector. Sampling points and a chemical inhibitor injection port were strategically placed on the pipeline. This paper focuses on the corrosion monitoring program performed in this pilot work so far. The main objectives of this corrosion program were to:Establish the severity of surface and subsurface corrosion in the systemValidate the corrosion monitoring techniquesInvestigate the benefits of corrosion inhibitor and plastic coated surface and subsurface tubularProvide recommendations and insights for the planned full field waterflood development. The pilot corrosion surveillance strategy was to analyze the corrosion data on daily basis. Specific daily measurements included pH, Total Suspend Solid (TSS) in milligram per liter (mg/L), corrosion rate measured from Linear Polarized Resistance (LPR) in Mills per Year (M/Y) (M=0.001 inch) and chemical injection inhibitor concentration in Parts per Million (PPM). These measurements were recorded and analyzed by a dedicated ‘pilot team’ which was established to maximize the value and guidance from this pilot work. The producing wells were completed with 3 1/2 " N-80 tubing and gaslift mandrels. Subsurface corrosion measurements were acquired in the producers completion using baseline and subsequent wireline MVRT corrosion logs. The ‘subsequent’ corrosion logs were event driven, and focused on those producers where water breakthrough was experienced. In general, a good correlation between cumulative water production and corrosion severity was observed, and a fair correlation between increased depth and increased corrosion was observed.

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This paper was prepared for presentation at the 8th Abu Dhabi International Petroleum Exhibition and Conference held in Abu Dhabi, U.A.E., 11-14 October 1998.

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