A drill bit for coupling in use downhole drilling apparatus, the drill bit comprising: an annular coring drill bit that is rotatable to cut a formation bore face to create a core plug, a concentric drill bit that can be repeatedly axially moved (such as by oscillation (such as a vibration) and/or impact) to break the core plug.

A drill bit for coupling in use downhole drilling apparatus, the drill bit comprising: an annular coring drill bit that is rotatable to cut a formation bore face to create a core plug, a concentric drill bit that can be repeatedly axially moved (such as by oscillation (such as a vibration) and/or impact) to break the core plug.

A drill bit performs pilot rock-breaking using an outer annular drill bit and breaks a central rock pillar using a central drill bit mounted in the middle of the annular drill bit and located inside a drill bit body to induce unloading of a bottom hole stress. A method mixes rock debris produced by rock breaking of the central drill bit as abrasive with the drilling fluid flowing into the entire drill bit as abrasive jet liquid phase to form an abrasive jet. The method includes obtaining an annular borehole by braking, and breaking the rock pillar at the inner side of the annular borehole to induce unloading of the bottom hole stress, mixing the rock debris produced by breaking the rock pillar at the inner side of the annular borehole as abrasive with the drilling fluid entering the drill bit to form an abrasive jet.

A hybrid wellbore drilling bit assembly and a method for drilling a borehole with a hybrid wellbore drilling bit assembly are described. A base connects the hybrid wellbore drill bit assembly to a drill string. Blades are connected to the base, extending away from the base along the longitudinal axis and tapering toward the longitudinal axis of the hybrid wellbore drilling bit assembly base creating a tapered cavity. The blades have cutters to shear a core of the Earth that enters the cavity. The core of Earth expands in the cavity. A crusher is connected to the base and positioned within the cavity which crushes the core of Earth.

A hybrid wellbore drilling bit assembly and a method for drilling a borehole with a hybrid wellbore drilling bit assembly are described. A base connects the hybrid wellbore drill bit assembly to a drill string. Blades are connected to the base, extending away from the base along the longitudinal axis and tapering toward the longitudinal axis of the hybrid wellbore drilling bit assembly base creating a tapered cavity. The blades have cutters to shear a core of the Earth that enters the cavity. The core of Earth expands in the cavity. A crusher is connected to the base and positioned within the cavity which crushes the core of Earth.

A core drilling apparatus and a method for converting between a core drilling assembly and a full-diameter drilling assembly by means of a lifting device and a coring drill head with closure elements and integrated cutting implements. The lifting device comprises a release mechanism that when activated, releases forces acting on the lifting device, such that when the lifting device is in an upper position when activated, the lifting device lowers an inner tubing thereby pushing the closure elements of the drill head in an open position, and when the lifting device is in a lower position when activated, the lifting device lifts the inner tubing from the closure elements such that the closure elements is in a closed or partly closed position.

A drill bit comprises a first and a second body received within the first body. Each of the first body and second body has a respective crown, each crown having an inner and an outer operative circumference. The outer operative circumference of the second body and the inner operative circumference of the first body can define a first volume that can receive a tubular core sample. The second body can define a break surface that breaks the tubular core sample into core pieces. The drill bit can be employed in a borehole with a reverse circulation system that pumps fluid around an outer surface of the bit, and returning fluid can carry the core pieces out of the borehole.

A drill bit comprises a first and a second body received within the first body. Each of the first body and second body has a respective crown, each crown having an inner and an outer operative circumference. The outer operative circumference of the second body and the inner operative circumference of the first body can define a first volume that can receive a tubular core sample. The second body can define a break surface that breaks the tubular core sample into core pieces. The drill bit can be employed in a borehole with a reverse circulation system that pumps fluid around an outer surface of the bit, and returning fluid can carry the core pieces out of the borehole.

A drill bit comprises a first and a second body received within the first body. Each of the first body and second body has a respective crown, each crown having an inner and an outer operative circumference. The outer operative circumference of the second body and the inner operative circumference of the first body can define a first volume that can receive a tubular core sample. The second body can define a break surface that breaks the tubular core sample into core pieces. The drill bit can be employed in a borehole with a reverse circulation system that pumps fluid around an outer surface of the bit, and returning fluid can carry the core pieces out of the borehole.

A drill bit comprises a first and a second body received within the first body. Each of the first body and second body has a respective crown, each crown having an inner and an outer operative circumference. The outer operative circumference of the second body and the inner operative circumference of the first body can define a first volume that can receive a tubular core sample. The second body can define a break surface that breaks the tubular core sample into core pieces. The drill bit can be employed in a borehole with a reverse circulation system that pumps fluid around an outer surface of the bit, and returning fluid can carry the core pieces out of the borehole.