The corrosion of carbon steel tubulars is an important completion integrity management issue. It is critical for the safe lifetime containment of well fluids, to avoid risk to people, property and the environment, and to avoid costly workover and repair during the well's life.

An effective tubing lifetime corrosion prediction model (VirtualCalliper) was developed to improve the management of integrity in carbon steel wells. The model has proved to be an order of magnitude more accurate than many widely used corrosion models, when predicting the internal corrosion of producer and injector wells.

The main reasons for this are:

  • In addition to the standard parameters considered in most corrosion prediction models, VirtualCalliper accounts for the influences of well architecture, water cut development, water salinity, erosion corrosion and H2S corrosion.

  • The model has been rigorously tuned with extensive field corrosion inspection data from a large number of well calliper surveys

  • The use of a well performance simulator output as the input files for key well parameters, ensures accurate modelling of temperature, pressure and flow characteristics across the whole well profile.

  • The software is capable of time stepping to consider the impact of historical and future changes to parameters such as lift gas, oil, gas and water rates.

  • The corrosion model output can be integrated with completion stress analysis (CSA), to enable the remaining tubing life to be predicted and to assess potential problems during well operations or workover.

VirtualCalliper has been proven in a number of fields. It has been used to plan a risk-based sequence of well workover priorities in a large, mature North Sea field. This has been achieved without the cost, HSE risk and lost production associated with well interventions to obtain calliper survey data.

This paper describes the structure and main functions of the model. Three case studies, used during the model development to compare the predicted tubing metal loss from VirtualCalliper and tubing metal loss measured from calliper surveys, are also presented.

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