ABSTRACT:

The ability to make drill pipe connections while maintaining uninterrupted circulation to the well is now a reality. In development since 2000, the Continuous Circulation System (CCS), was successfully introduced in 2004 and used to drill previously undrillable formations, enabling valuable well data to be recorded through potential oil and gas reservoirs. The CCS allows the use of Balanced Pressure Drilling to drill formations with a narrow Pore Pressure/Fracture Pressure Gradient window. With uninterrupted circulation during connections, a steady ECD can be established and maintained in the Critical Pressure Zone between the Pore and Fracture Pressure gradients. The well is controlled by the ECD with a mud weight lower than that required to balance the Pore Pressure. Continuous circulation also avoids creating the pressure fluctuations and stresses imposed on the wellbore when starting and stopping circulation to make connections conventionally. This paper will review the development of the CCS and its applications so far. It will discuss the range and selection of potential applications and cover rig selection and installation requirements to make successful use of the system

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