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

Claim 0:
1. A method for directional drilling of a borehole with a borehole bottom, the method comprising:
providing a drill bit, said drill bit being connected to a lower end of a drill string and comprising:
a bit face, which during use faces the borehole bottom,
one or more abrasive jet nozzles configured for directing 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 adjacent azimuthal positions,
an intermediate space between a bit fluid inlet port of the drill bit 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;

upstream of said bit fluid inlet port, passing the stream of drilling fluid mixed with abrasive particles through a supply channel having an supply channel outlet at a substantially constant supply velocity,
simultaneously, rotating the drill bit, and thereby the one or more abrasive jet nozzles, at a rotational velocity and passing said stream of drilling fluid mixed with abrasive particles via the supply channel outlet and the bit fluid inlet port consecutively through the intermediate space, the one or more nozzle inlets, and the one or more abrasive jet nozzles into impingement with the borehole bottom, so as to deepen the borehole; and
during said rotating of the drill bit while passing of the stream of drilling fluid mixed with abrasive particles, varying concentrations of said abrasive particles along subsequent stream portions of said stream flowing through the abrasive jet nozzles of the drill bit, such that alternatingly the concentration of abrasive particles is high in a first stream portion and low in a subsequent second stream portion,
wherein said varying of the concentrations of the abrasive particles in the stream of drilling fluid mixed with abrasive particles comprises:
upstream of said bit fluid inlet port, passing said stream from the supply channel outlet subsequently, in parallel through a first channel and a second channel to first and second outlets thereof, respectively, and from the first and second outlets into the bit fluid inlet port, while, alternatingly,
during a first time period, deflecting into the first channel a majority of all abrasive particles in the stream that pass through the supply channel outlet, and
during a second time period, following the first time period, not deflecting into the first channel a majority of all abrasive particles in the stream that pass through said supply channel outlet, and
subsequently passing said stream from the first and second outlets into said one or more abrasive jet nozzles,

wherein the difference between a flow resistance to said drilling fluid mixed with abrasive particles in said first channel and a flow resistance to said drilling fluid mixed with abrasive particles in said second channel results in a difference between a first velocity at which said drilling fluid mixed with abrasive particles flows through said first channel and a second velocity at which said drilling fluid mixed with abrasive particles flows through said second channel,
wherein said difference between said first and second velocities is such that, downstream of the first and second outlets,
the majority deflected into the first channel during the first time period and the abrasive particles passed into the second channel during the second time period, together with drilling fluid passed into the first and second channel during the first and second time period, respectively, are combined to form the first stream portion, and
the abrasive particles passed into the first channel during the second time period and the abrasive particles passed into the second channel during a first time period following the second time period together with drilling fluid passed into the first and second channel during the second time period and a first time period following the second time period, respectively, are combined to form the second stream portion.