The present invention relates to a collapsible drill bit for use in formation drilling and a method of formation drilling. The drill bit includes a main body having a first cutting diameter and includes a front end with a cutting face supporting one or more cutting elements and a rear end configured to operatively connect to a drill string. The drill bit also includes a retractable portion between the front end and the rear end, the retractable portion including at least one cutting face supporting one or more cutting elements, the retractable portion configured to move between an expanded position in which the retractable portion has a second cutting diameter and a collapsed position in which the retractable portion has a diameter less than or equal to the first cutting diameter. Wherein the retractable portion is caused to move into the collapsed position upon an application of a sufficient force.

A downhole tool includes a housing; a seal that at least partially circumscribes an external surface of the housing and is configured to fluidly seal the housing against a wellbore tubular positioned in a wellbore; a hydraulic motor assembly positioned in the housing and including a hydraulic rotor fluidly coupled to an opening in the housing and a shaft coupled to the hydraulic rotor; and a tubular cutting assembly coupled to the hydraulic motor assembly. The tubular cutting assembly includes a bearing coupled to the shaft, and at least one cutting blade coupled to the bearing and operable to cut the wellbore tubular. The at least one cutting blade is configured to rotate in an extended position from the external surface of the housing in response to a flow of wellbore fluid circulated through the wellbore tubular and to the hydraulic motor assembly through the opening in the housing.

A method for removing material with a bit includes rotating a bit in a first direction, changing the rotational direction and rotating the bit in an opposing second direction. Rotation of the bit in the first direction and rotation of the bit in the second direction both remove material.

A downhole tool includes a housing; a seal that at least partially circumscribes an external surface of the housing and is configured to fluidly seal the housing against a wellbore tubular positioned in a wellbore; a hydraulic motor assembly positioned in the housing and including a hydraulic rotor fluidly coupled to an opening in the housing and a shaft coupled to the hydraulic rotor; and a tubular cutting assembly coupled to the hydraulic motor assembly. The tubular cutting assembly includes a bearing coupled to the shaft, and at least one cutting blade coupled to the bearing and operable to cut the wellbore tubular. The at least one cutting blade is configured to rotate in an extended position from the external surface of the housing in response to a flow of wellbore fluid circulated through the wellbore tubular and to the hydraulic motor assembly through the opening in the housing.