Abstract: A method includes conveying a casing cutting tool into the wellbore lined with at least one casing string and cement, and stroking the casing cutting tool over a predetermined axial length of the wellbore while ejecting fluid from one or more nozzles in the casing cutting tool and thereby forming a plurality of longitudinal cuts through the casing string and cement. The casing cutting tool is then rotated about its longitudinal axis at two or more axially offset locations along the predetermined axial length while ejecting fluid from nozzles and thereby forming a plurality of axially offset transverse cuts in the casing string and the cement. The longitudinal cuts and axially offset transverse cuts form wedges in the wellbore, and the wedges are dislodged from the wellbore to expose formation rock along the predetermined axial length.

Abstract: One disclosed method includes conveying a casing cutting tool into the wellbore lined with at least one casing string and cement, stroking the casing cutting tool over a predetermined axial length of the wellbore while ejecting fluid from one or more nozzles in the casing cutting tool and thereby forming a plurality of longitudinal cuts through the casing string and cement, rotating the casing cutting tool about its longitudinal axis at two or more axially offset locations along the predetermined axial length while ejecting fluid from nozzles and thereby forming a plurality of axially offset transverse cuts in the casing string and the cement, whereby longitudinal cuts and axially offset transverse cuts form wedges in the wellbore, and dislodging the wedges from the wellbore and thereby exposing formation rock along the predetermined axial length.

Abstract: A valve for a well pipe, the valve having the following parts: a valve collar connectable to the well pipe; an index piston coaxially positioned within the valve collar for longitudinal translation within the valve collar between closed, flow-open, and locked-open configurations; a detent in the index piston, wherein the detent restricts fluid flow in a circulation direction through a flow path through the index piston; a spring that biases the index piston toward the closed and locked-open configurations; and a plug of the valve collar that mechanically communicates with the index piston to be in corresponding closed, flow-open, and locked-open configurations.

Abstract: A valve for a well pipe, the valve having the following parts: a valve collar connectable to the well pipe; an index piston coaxially positioned within the valve collar for longitudinal translation within the valve collar between closed, flow-open, and locked-open configurations; a detent in the index piston, wherein the detent restricts fluid flow in a circulation direction through a flow path through the index piston; a spring that biases the index piston toward the closed and locked-open configurations; and a plug of the valve collar that mechanically communicates with the index piston to be in corresponding closed, flow-open, and locked-open configurations.

Abstract: A valve for a well pipe, the valve having the following parts: a valve collar connectable to the well pipe; an index piston coaxially positioned within the valve collar for longitudinal translation within the valve collar between closed, flow-open, and locked-open configurations; a detent in the index piston, wherein the detent restricts fluid flow in a circulation direction through a flow path through the index piston; a spring that biases the index piston toward the closed and locked-open configurations; and a plug of the valve collar that mechanically communicates with the index piston to be in corresponding closed, flow-open, and locked-open configurations.

Abstract: A method for reverse cementing may include providing a valve having a sliding sleeve, an outer sleeve situated about at least a portion of the sliding sleeve and connected to a casing string, and a spring configured to position the valve in an open position. The method may also include: running the casing string and valve into a well bore while the valve is in an open position; reverse cementing, while the valve is in an open position; and closing the valve after reverse cementing by allowing the valve to contact the well bore.

Abstract: A valve for a well pipe, the valve having the following parts: a valve collar connectable to the well pipe; an index piston coaxially positioned within the valve collar for longitudinal translation within the valve collar between closed, flow-open, and locked-open configurations; a detent in the index piston, wherein the detent restricts fluid flow in a circulation direction through a flow path through the index piston; a spring that biases the index piston toward the closed and locked-open configurations; and a plug of the valve collar that mechanically communicates with the index piston to be in corresponding closed, flow-open, and locked-open configurations.