Anti-rotation pad assemblies are provided for restraining rotation of a non-rotating housing in geologic drilling system. The anti-rotation pad assemblies include extensible members, which extend from an internal cavity in the anti-rotation pad assemblies and are capable of engaging a wellbore wall. The extensible members may include rollers that are biased radially outwardly to engage the wellbore wall such that the anti-rotation pad assemblies may move axially within the wellbore while restraining the non-rotating housing in a particular rotational orientation. Flow ports are defined in the anti-rotation pad assemblies to encourage mud flow through the internal cavity, and thereby discourage the accumulation and solidification of drilling fluids around the extensible members. The extensible members thus remain free to move under the bias of a biasing mechanism within the internal cavity and can thus effectively maintain the rotational orientation of the non-rotating housing in the wellbore.

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.

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.

A hybrid drill bit includes both fixed cutting elements and an adjustable cutting structure thereon. An adjustment mechanism is provided to allow an axial position of cutting elements at a leading end of the adjustable cutting structure to be adjusted with respect to an axial position of the fixed cutting elements. The adjustable cutting structure may include counter rotational cutting members mounted obliquely with respect to a bit body rotational axis, and the adjustment mechanism may dynamically support the adjustable cutting structure such that the axial position of the cutting elements may be adjusted as the drill bit is in operation within a wellbore. The axial position may be adjusted by altering a weight applied to the drill bit within the wellbore.

A hybrid drill bit includes both fixed cutting elements and an adjustable cutting structure thereon. An adjustment mechanism is provided to allow an axial position of cutting elements at a leading end of the adjustable cutting structure to be adjusted with respect to an axial position of the fixed cutting elements. The adjustable cutting structure may include counter rotational cutting members mounted obliquely with respect to a bit body rotational axis, and the adjustment mechanism may dynamically support the adjustable cutting structure such that the axial position of the cutting elements may be adjusted as the drill bit is in operation within a wellbore. The axial position may be adjusted by altering a weight applied to the drill bit within the wellbore.

A method of manufacturing, assembling, configuring, and/or using a hybrid drill bit is disclosed. An illustrative example includes inserting a rolling cutting structure into a central bore of a bit body through an upper connector section of the bit body toward a lower end portion of the bit body. The bit body has a rotational axis and a plurality of blades at the lower end portion. The upper connector section is configured to be coupled to a lower end of a drill string. Each of the plurality of blades extends radially from the bit body about the rotational axis at the lower end portion and includes a plurality of cutters embedded therein.