Splined/grooved 2 piece bit assembly

A downhole tool, comprising:

• a two part drilling and running tool, including:
• a conveyance;
• a smaller assembly coupled to an end of the conveyance, the smaller assembly having a smaller assembly spline or slot located along an entire length LS thereof;
• and
• a larger bit assembly slidably coupled to the conveyance, the larger bit assembly including a larger bit assembly other of the slot or spline, wherein the smaller assembly spline or slot and the larger bit assembly other of the slot or spline are configured to engage one another to rotationally fix the smaller assembly relative to the larger bit assembly as the smaller assembly and the larger bit assembly slidingly engage one another to form a combined bit assembly;
• and
• a whipstock assembly coupled to the two part drilling and running tool using a coupling mechanism.

A well system, comprising:

• a main wellbore located within a subterranean formation;
• and
• a downhole tool positioned within the main wellbore, the downhole tool including:
• a two part drilling and running tool, the two part drilling and running tool including:
• a conveyance;
• a smaller assembly coupled to an end of the conveyance, the smaller assembly having a smaller assembly spline or slot located along an entire length LS thereof;
• and
• a larger bit assembly slidably coupled to the conveyance, the larger bit assembly including a larger bit assembly other of the slot or spline, wherein the smaller assembly spline or slot and the larger bit assembly other of the slot or spline engage one another to rotationally fix the smaller assembly relative to the larger bit assembly as the smaller assembly and the larger bit assembly slidingly engage one another to form a combined bit assembly;
• and
• a whipstock assembly coupled to the two part drilling and running tool using a coupling mechanism.

A method for forming a well system, comprising:

• forming a wellbore within a subterranean formation;
• positioning a downhole tool within the wellbore, the downhole tool including:
• a two part drilling and running tool, the two part drilling and running tool including:
• a conveyance;
• a smaller assembly coupled to an end of the conveyance, the smaller assembly having a smaller assembly spline or slot located along an entire length LS thereof;
• and
• a larger bit assembly slidably coupled to the conveyance, the larger bit assembly including a larger bit assembly other of the slot or spline, wherein the smaller assembly spline or slot and the larger bit assembly other of the slot or spline engage one another to rotationally fix the smaller assembly relative to the larger bit assembly as the smaller assembly and the larger bit assembly slidingly engage one another to form a combined bit assembly;
• and
• a whipstock assembly coupled to the two part drilling and running tool using a coupling mechanism;
• rotating the conveyance, the smaller assembly spline or slot and the larger bit assembly other of the slot or spline causing the whipstock assembly to rotate with the conveyance;
• and
• retracting the smaller assembly uphole, the smaller assembly engaging with the larger bit assembly to form a combined bit assembly.