Advanced Corrosion Analysis Perceptions through Array Pulse and Conventional Electromagnetic Technologies Combination

Abstract The main objective of the well integrity system is to prevent the appearance of unwanted fluids in annulus. There are many physical methods to assess tubular metal loss, but most of them suffer from specific conditions that affect their readings, which leads to the absence of a proper answer about the condition of pipes. The solution could be a new technology that is related to the measurement of electromagnetic (EM) fields but utilizing array sensors to focus in specific pipe area. This multi-sensor works in combination with conventional EM tool, which measures the wall thicknesses of outer casings. It includes a specific sensor that helps to capture the eccentricity of the tool inside the tubing and the tubing inside the casing. The array pulse and traditional electromagnetic tool consist of a generating-and-receiving electromagnetic coil that is wound on a core. It emits a magnetic pulse along the pipe during survey. Ring currents induced in the pipe body generate an electromagnetic field in receiver coils. Signal decay characteristics are defined by thickness of the metal. The output of the survey is 8 sectorial thicknesses for the 1st barrier (usually it is tubing). The conventional EM tool provides the average thickness of the 2nd and 3rd barriers. The survey is run under the shut-in condition during up pass. Combination of Array Pulse and Conventional Electromagnetic technologies was used in one of the oil producers to prove its efficiency. Based on survey results moderate corroded intervals of the tubing were found out with different metal loss level by sectors. New insights about localized corrosion spots were revealed by Array Pulse tool, meanwhile the conventional EM tool detected them with less metal loss due to averaging of EM signal at each specific depth. Conventional EM survey results showed the appearance of several extensive corrosion zones in the 1st and 2nd casings. The measurement of eccentricity of the tool inside the tubing and the tubing inside the casing provided the absence of the borehole assembly decentralization. Meanwhile there is some tubing laying inside the casing in acceptable values, which does not affect the Pulse data. The array pulse tool is a new generation of electromagnetic survey methods that has the all-around sensing. It is not scratching the pipe wall during survey. And it is effective in chrome completion and insensitive to surface deposits. It works in all fluids environments including the gas in the wellbore. The combination of Array Pulse and Conventional EM tools is increasing the efficiency of corrosion logging results. Sectorial pulse logging helps to not pass by localized metal loss zones. Specific eccentricity sensors help to identify decentralization of the tool inside the tubing and the tubing inside the casing.