Accurate Corrosion Prediction Through an Integrated Approach

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe ability to optimize the use of carbon steel in corrosive service presents many economic advantages, including minimizing the use of expensive corrosion resistant alloys, reducing well count by enabling optimized large bore completions, and eliminating additional offshore pipelines and facilities. An integrated approach to corrosion modeling and testing is employed by ExxonMobil to reliably extend the application of carbon steel.The integrated approach to predicting corrosion has five primary elements:1. Rigorously establish the environmental conditions by conducting thermodynamic and compositional hydraulic analyses, and characterize how these conditions are expected to change over time. 2. Identify the local environmental conditions and the types of corrosion that are expected to occur (e.g., weight loss, pitting, environmental cracking), including sensitivity and upset cases. 3. Conduct realistic corrosion tests under the identified field conditions by simulating brine chemistry, dissolved acid gas concentrations, hydrocarbon effects, fluid shear stresses, and flow regime in appropriate laboratory equipment. Specialized laboratory test apparati, such as a large-diameter sour, multiphase flow loop and large-volume highpressure high temperature autoclave test cells, have been designed and constructed to ensure proper reproduction of field conditions. 4. Mathematically extrapolate the results of the laboratory tests to the field, enabling calculation of expected tubular life. 5. Conduct life cycle cost analysis. This paper will describe how this integrated approach to predicting corrosion is used to evaluate the use of carbon steel in oil and gas production environments. Special emphasis will be placed on the prediction of pitting corrosion in H 2 Scontaining environments.

An Evaluation of Production Casing Corrosion Due to Ingress of Sour Gas in the Tubing-Casing Annulus

“…Over time the industry has studied, discussed and documented different types of corrosion mechanisms and corrosion management solutions. [1][2][3] The limits in inspecting and monitoring the onset of corrosion have also been explored and recognised. One of the notable technology limits that the industry struggles with today is the ability to monitor the condition of concentric casing strings in a well.…”

Integrated Approach to Quantify L80 Tubing Corrosion for High-rate Sour Gas Wells

“…The integrated approach has the following ele ments: (1) rigorously establish tubular environmental conditions, (2) accurately simulate environmental conditions (acid gas concentratio ns, water cut, and water composition) in the laboratory, (3) mathematically extrapolate laboratory weight loss and pitting to predict tubing life, and (4) validate tubing life pr edictions with field caliper data. [2][3][4] This paper describes the application of the int egrated approach to pre dict L80 tubular corrosion for sour gas wells, and the validation of the corrosion prediction using field caliper data.…”