Abstract: An underreamer for increasing a diameter of a wellbore. The underreamer may include a body with first and second cutter blocks coupled to the body. The first cutter block may have a recess formed therein, and the second cutter block may be positioned in the recess. The first and second cutter blocks may move between retracted and expanded states. In the retracted state, the first and second cutter blocks may have an outer diameter less than or equal to an outer diameter of the body. In the expanded state, the first and second cutter blocks may have different outer diameters, with each being greater than the outer diameter of the body. A method may include running the underreamer into a wellbore, expanding the first and second cutter blocks, and moving the underreamer axially in the wellbore to increase the diameter of the wellbore.

Abstract: An underreamer for increasing a diameter of a wellbore. The underreamer may include a body with first and second cutter blocks coupled to the body. The first cutter block may have a recess formed therein, and the second cutter block may be positioned in the recess. The first and second cutter blocks may move between retracted and expanded states. In the retracted state, the first and second cutter blocks may have an outer diameter less than or equal to an outer diameter of the body. In the expanded state, the first and second cutter blocks may have different outer diameters, with each being greater than the outer diameter of the body. A method may include running the underreamer into a wellbore, expanding the first and second cutter blocks, and moving the underreamer axially in the wellbore to increase the diameter of the wellbore.