Abstract: A method for managed pressure drilling comprising: extending a drilling riser with a drill string from a floating installation to a subsea blow-out preventer stack; providing a first fluid in the drilling riser annulus and a second fluid in a fluid conduit extending from the floating installation, where the first fluid has a higher density than the second fluid; circulating the second fluid through a control valve which is fluidly connected to the fluid conduit and operating the control valve to apply a surface back-pressure so as to obtain a pre-determined, desired combined hydrostatic and frictional circulation pressure below the subsea blow-out preventer stack.

Abstract: A protection system for a drilling riser. The drilling riser includes a main drilling riser bore and a drilling riser annulus and extends from a floating installation to a location on a seafloor and is fluidly connected to a subsea BOP. The system includes a fluid conduit which extends from the floating installation to a lower region of the drilling riser. The fluid conduit is fluidly connected with the drilling riser annulus in the drilling riser. The fluid conduit provides at least one of a rapid pressure relief and a fluid bypass for the main drilling riser bore to prevent the drilling riser from an uncontrolled pressure build-up due to an inadvertent plugging or a restriction resulting in a maximum allowable working pressure (MAWP) of the drilling riser being exceeded, if a restriction, a plug or a blockage exists in the drilling riser annulus or in riser outlets.

Abstract: A method for managed pressure drilling comprising: extending a drilling riser (2) with a drill string (20) from a floating installation (52) to a subsea blow-out preventer stack (1); providing a first fluid in the drilling riser annulus (12) and a second fluid in a fluid conduit (6,7) extending from the floating installation (52), where the first fluid has a higher density than the second fluid; circulating the second fluid through a control valve (31) which is fluidly connected to the fluid conduit (6,7) and operating the control valve (31) to apply a surface back-pressure so as to obtain a pre-determined, desired combined hydrostatic and frictional circulation pressure below the subsea blow-out preventer stack (1).

Abstract: A deep water drilling riser pressure relief system includes a drilling riser extending from a surface down to a BOP stack arranged subsea. The drilling riser comprises a drilling riser slip joint, an annular preventer arranged below the drilling riser slip joint, and at least one pressure relief device arranged in a lower part of the drilling riser. The at least one pressure relief device is configured to open so as to discharge a fluid from the drilling riser to the sea if a pressure difference between an inside and an outside of the drilling riser exceeds a predetermined threshold.

Abstract: A protection system for a drilling riser. The drilling riser includes a main drilling riser bore and a drilling riser annulus and extends from a floating installation to a location on a seafloor and is fluidly connected to a subsea BOP. The system includes a fluid conduit which extends from the floating installation to a lower region of the drilling riser. The fluid conduit is fluidly connected with the drilling riser annulus in the drilling riser. The fluid conduit provides at least one of a rapid pressure relief and a fluid bypass for the main drilling riser bore to prevent the drilling riser from an uncontrolled pressure build-up due to an inadvertent plugging or a restriction resulting in a maximum allowable working pressure (MAWP) of the drilling riser being exceeded, if a restriction, a plug or a blockage exists in the drilling riser annulus or in riser outlets.

Abstract: A method for predicting a formation of hydrates in a wellbore/riser annulus during a drilling operation. The method includes logging actual mud properties. Actual sets of pressure and temperature data at given locations/intervals in the wellbore or in the drilling riser annulus are continuously measured and/or calculated. A theoretical temperature profile for the formation of hydrates dependent on mud properties and pressure as a function of a true vertical depth in a well is determined. The theoretical temperature profile for the formation of hydrates in a control system is stored. The measured and/or calculated actual sets of pressure and temperature data is compared with the theoretical temperature profile for the formation of hydrates. A signal is issued if the measured and/or calculated actual sets of pressure and temperature data falls below or is lower than a predefined safety margin for the theoretical temperature profile for the formation of hydrates.

Abstract: A method for detecting an influx in a wellbore with first and second pressure transmitters arranged in a fixed vertical distance in relation to each other. The method includes calculating an expected density of a return flow between the first and second pressure transmitters, continuously measuring an actual density of the return flow based on a measured pressure at the first and second pressure transmitters, comparing the calculated expected density of the return flow and the measured actual density of the return flow to determine the influx in the wellbore, and predicting a probability of hydrates forming in the well by measuring a temperature via a temperature transmitter arranged in a section of the well adjacent to the first and/or the second pressure transmitter, and using the temperature together with the measurements from the first and second pressure transmitters.

Abstract: A method for predicting a formation of hydrates in a wellbore or in a riser annulus includes logging actual mud properties, continuously measuring and/or calculating actual sets of pressure and temperature data at given locations/intervals in the wellbore or in the riser annulus, determining a theoretical temperature profile for the formation of hydrates dependent on mud properties and pressure as a function of a true vertical depth in a well, storing the theoretical temperature profile for the formation of hydrates in a control system, comparing the measured and/or calculated actual sets of pressure and temperature data with the theoretical temperature profile for the formation of hydrates, and issuing a signal from a control system if the measured and/or calculated actual sets of pressure and temperature data falls below or is lower than a predefined safety margin for the theoretical temperature profile for the formation of hydrates.

Abstract: A method for detecting an influx in a wellbore with first and second pressure transmitters arranged in a fixed vertical distance in relation to each other. The method includes calculating an expected density of a return flow between the first and second pressure transmitters, continuously measuring an actual density of the return flow based on a measured pressure at the first and second pressure transmitters, comparing the calculated expected density of the return flow and the measured actual density of the return flow to determine the influx in the wellbore, and predicting a probability of hydrates forming in the well by measuring a temperature via a temperature transmitter arranged in a section of the well adjacent to the first and/or the second pressure transmitter, and using the temperature together with the measurements from the first and second pressure transmitters.

Abstract: A deep water drilling riser pressure relief system includes a drilling riser extending from a surface down to a BOP stack arranged subsea. The drilling riser comprises a drilling riser slip joint, an annular preventer arranged below the drilling riser slip joint, and at least one pressure relief device arranged in a lower part of the drilling riser. The at least one pressure relief device is configured to open so as to discharge a fluid from the drilling riser to the sea if a pressure difference between an inside and an outside of the drilling riser exceeds a pre-determined threshold.

Abstract: A fluid diverter system for a drilling facility comprises a diverter housing (15; 15?) fluidly connected to a tubular (3, 42, 43) extending to a subsea well. The diverter housing (15; 15?) comprising a movable diverter element (2) for closing off the diverter housing, a first fluid conduit (44) connected to a mud system and comprising a first valve (5), at least one second fluid conduit (20; 20?) leading from an outlet (46; 46?) in the diverter housing to an overboard location and comprising a second valve (1; 48), and a third fluid conduit (16) connected to a mud/gas separator (MGS) (13) and comprising a third valve (4). The MGS (13) is arranged below the outlet (50) of the diverter line, whereby riser fluids may be fed from the diverter housing (15) to the MGS (13) by means of gravity flow. The diverter valve (1; 48) on a leeward side of the drilling facility is configured to be open before the diverter element (2) closes around the tubular (3).

Abstract: A fluid diverter system for a drilling facility comprises a diverter housing (15; 15?) fluidly connected to a tubular (3, 42, 43) extending to a subsea well. The diverter housing (15; 15?) comprising a movable diverter element (2) for closing off the diverter housing, a first fluid conduit (44) connected to a mud system and comprising a first valve (5), at least one second fluid conduit (20; 20?) leading from an outlet (46; 46?) in the diverter housing to an overboard location and comprising a second valve (1; 48), and a third fluid conduit (16) connected to a mud/gas separator (MGS) (13) and comprising a third valve (4). The MGS (13) is arranged below the outlet (50) of the diverter line, whereby riser fluids may be fed from the diverter housing (15) to the MGS (13) by means of gravity flow. The diverter valve (1; 48) on a leeward side of the drilling facility is configured to be open before the diverter element (2) closes around the tubular (3).