Patent ID: 11879335
Assignee: CANOPUS DRILLING SOLUTIONS HOLDING B.V.
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 10:
11. A directional drilling system for directional drilling of a borehole with a borehole bottom, wherein the drilling system is connectable to a tubular drill string,
the directional drilling system comprising:
a drill bit, comprising:
a bit face, which during use faces the borehole bottom,
a bit fluid inlet port,
one or more abrasive jet nozzles configured for ejecting a stream of drilling fluid mixed with abrasive particles into impingement with the borehole bottom in the form of an abrasive jet, which one or more abrasive jet nozzles, if in plural, are arranged at different azimuthal positions, and
an intermediate space between the bit fluid inlet port and said one or more abrasive jet nozzles, each of the one or more abrasive jet nozzles having a nozzle inlet for fluid communication with the intermediate space, from which each of the nozzle inlets extends; and

a sub, connected at a downhole end thereof to the drill bit, and at another end thereof to the tubular drill string, the sub comprising:
a sub fluid inlet port, fluidly connected to a supply channel through the drill string to receive from said supply channel the stream of drilling fluid mixed with abrasive particles when the system is connected to the drill string, and
a sub fluid outlet port, fluidly connected to the bit fluid inlet port,

wherein the sub further comprises, fluidly connected to the sub fluid inlet port, downstream thereof, a modulation unit configured to cause a variation of a concentration of abrasive particles along stream portions of the stream received from the supply channel that are subsequently passed through the sub fluid outlet port into the bit fluid inlet port, the modulation unit comprising:
a first channel having a first flow resistance to the drilling fluid mixed with abrasive particles, a first inlet, and a first outlet fluidly connected to the sub fluid outlet port,
a second channel arranged in parallel to the first channel, having a second flow resistance to the drilling fluid mixed with abrasive particles, a second inlet, and a second outlet fluidly connected to the sub fluid outlet port (20o),
a particle deflection device between the sub fluid inlet port and the first and second inlets, comprising one or more actuators, and being connected to a control unit of the system,

wherein the particle deflection device is configured to periodically,
during a first time period, deflect into the first inlet a majority of all abrasive particles received from the supply channel through the sub bit fluid inlet port, and
during a second time period following the first time period, not deflect into the first inlet a majority of all abrasive particles in the stream received from the supply channel through the sub bit fluid inlet port,

wherein the first and second channel are embodied such that a difference between the first flow resistance and the second flow resistance results in a velocity difference between said drilling fluid mixed with abrasive particles passing through said first channel and said drilling fluid mixed with abrasive particles passing through said second channel,
wherein said velocity difference is such that in a combination section downstream of the first and second outlets, the majority deflected into the first inlet during the first time period and the abrasive particles passed into the second inlet during the second time period, together with any of said drilling fluid passed into the first and second inlet during the first and second time period, respectively, are combined into one of said stream portions, and abrasive particles passed into the first inlet during the second time period and abrasive particles passed into the second inlet during a first time period following the second time period, together with any drilling fluid passed into the first inlet during the second time period and into the second inlet during a first time period following the second time period, respectively, into a subsequent one of said stream portions.