Abstract

A very challenging HPHT well has been drilled utilizing a Managed Pressure Drilling System comprised of an advanced ECD Management System with automatic decision support, and real time simulations using state-of-the art models. The System uses all available real time drilling data (surface and downhole) in combination with real time modelling to monitor and optimize the drilling process. Especially the dynamic well pressure and the allowable drilling window (pore / fracture pressures and well stability limits) are focused on. The information is used to visualize the wellbore in 3D in real time. It has been implemented in Total E&P Norge TASC (Total Activities Support and Collaboration) Center in Norway.The system is composed of the following elements:

  • An advanced and fast integrated wellbore flow and thermal simulator modeling the thermohydraulics effects dynamically, and also the interaction between flow and temperature effects in real time.

  • Automatic quality check and corrections of drilling data; making them suitable for processing by computer models

  • Real time supervision of the drilling window using time based drilling data as well as drilling models

  • Diagnostics of the drilling state and conditions. This is obtained from comparing model predictions with measured data.

  • Automatic forward looking of the ECD

  • A Virtual Wellbore, with advanced visualization of the downhole process.

  • Data flow and computer infrastructure

Among the challenges during planning and drilling of this well have been:

  • Very small window between pore and fracture pressure. RT ECD simulations were performed with an advanced hydraulic and thermal wellbore model, and automatic supervision of the margins versus pore and fracture limits was performed.

  • Increased probability for instabilities in the tight window. Was mitigated by RT stability modeling during drilling.

  • Uncertainties in pore pressure predictions. Was mitigated by updating predictions during drilling.

Experiences from the drilling as well as use of the MPD System will be summarized and presented. The supervision and diagnosis functionalities have been useful in particular.

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