A method includes advancing a drill bit into a formation to form core sample pieces. The drill bit has a central axis and includes a crown defining an inner operative circumference. The crown is configured to form a core sample. A core receiving space is configured to receive the core sample as the drill bit is advanced into the formation. A base surface is spaced from the cutting face along the central axis of the drill bit. The base surface is configured to break apart portions of the core sample to form core sample pieces. The method can further include associating the core sample pieces with respective depths at which the core sample pieces were separated from the formation.

A method includes advancing a drill bit into a formation to form core sample pieces. The drill bit has a central axis and includes a crown defining an inner operative circumference. The crown is configured to form a core sample. A core receiving space is configured to receive the core sample as the drill bit is advanced into the formation. A base surface is spaced from the cutting face along the central axis of the drill bit. The base surface is configured to break apart portions of the core sample to form core sample pieces. The method can further include associating the core sample pieces with respective depths at which the core sample pieces were separated from the formation.

Methods and devices for the execution of core drillings in a material by a drilling unit, which makes use of a drill bit, and such drill bits that are made up of a hollow cylindrical core barrel, which has an end plate at its rear end and abrasion elements, which serve the abrasion of material, at the front end as well as at least two high-pressure jet nozzles, which can be connected with a high-pressure source of a blasting medium. The high-pressure jet nozzles are arranged on the inner surface of the core barrel and/or its end plate and are oriented into the inside of the core barrel. As a result of a combined forward motion and rotation of the drill bit, a drilling core is formed from which an abrasion takes place by means of the blasting medium, whereby overburden is removed from the drill bit.

Methods and devices for the execution of core drillings in a material by a drilling unit, which makes use of a drill bit, and such drill bits that are made up of a hollow cylindrical core barrel, which has an end plate at its rear end and abrasion elements, which serve the abrasion of material, at the front end as well as at least two high-pressure jet nozzles, which can be connected with a high-pressure source of a blasting medium. The high-pressure jet nozzles are arranged on the inner surface of the core barrel and/or its end plate and are oriented into the inside of the core barrel. As a result of a combined forward motion and rotation of the drill bit, a drilling core is formed from which an abrasion takes place by means of the blasting medium, whereby overburden is removed from the drill bit.

A rock formation drill bit assembly with electrodes includes a drill bit including a hollow portion that extends along a longitudinal axis of the drill bit. The hollow portion extends from a first end to a second end opposing the first end. Cutters as positioned on the first end. The cutters are configured to cut the rock formation resulting in a rock core protruding from the rock formation into the hollow portion. The rock core includes a circumferential surface. Multiple electrodes are positioned within an inner circumferential surface of the hollow portion. The multiple electrodes are configured to apply electrical discharge across multiple locations on the circumferential surface of the rock core. The electrical discharge causes the rock core to fracture.

A rock formation drill bit assembly with electrodes includes a drill bit including a hollow portion that extends along a longitudinal axis of the drill bit. The hollow portion extends from a first end to a second end opposing the first end. Cutters as positioned on the first end. The cutters are configured to cut the rock formation resulting in a rock core protruding from the rock formation into the hollow portion. The rock core includes a circumferential surface. Multiple electrodes are positioned within an inner circumferential surface of the hollow portion. The multiple electrodes are configured to apply electrical discharge across multiple locations on the circumferential surface of the rock core. The electrical discharge causes the rock core to fracture.

The present invention relates to a downhole drilling tool system of torque self-balancing and belongs to a technical field of drilling engineering equipment. The drilling tool system consists of an assembly of internal and external drill bits, power components, a pressure adjustment system for internal and external drill bits, a mud circulating system, and an unfreezing system. The present invention employs a dual drill bit of internal and external drill bits to crush rocks by inverse rotations, which realizes the drilling with slight disturbing to the surrounding rock; the torque self-balancing of the drill bit and the power system is realized as a whole without the torque effect to the upper drilling tool by utilizing the stator group and the rotor group of the power motor to drive the external and internal drill bits respectively; it is only necessary to trip the winch apparatus for the drilling tool on the ground to realize the normal operations of drilling, tripping, and logging-while-drilling by integrating the power source, mud circulating system and logging system, etc. into the drilling tool; the winch hoists up the drilling tool to remove rock particles at the sticking point by alternative positive and reverse rotations of the drill bit for unfreezing in order to realize the unfreezing when got stuck.

The present invention relates to a downhole drilling tool system of torque self-balancing and belongs to a technical field of drilling engineering equipment. The drilling tool system consists of an assembly of internal and external drill bits, power components, a pressure adjustment system for internal and external drill bits, a mud circulating system, and an unfreezing system. The present invention employs a dual drill bit of internal and external drill bits to crush rocks by inverse rotations, which realizes the drilling with slight disturbing to the surrounding rock; the torque self-balancing of the drill bit and the power system is realized as a whole without the torque effect to the upper drilling tool by utilizing the stator group and the rotor group of the power motor to drive the external and internal drill bits respectively; it is only necessary to trip the winch apparatus for the drilling tool on the ground to realize the normal operations of drilling, tripping, and logging-while-drilling by integrating the power source, mud circulating system and logging system, etc. into the drilling tool; the winch hoists up the drilling tool to remove rock particles at the sticking point by alternative positive and reverse rotations of the drill bit for unfreezing in order to realize the unfreezing when got stuck.

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 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.